1 (* ========================================================================= *)
2 (* Proof of Bertrand conjecture and weak form of prime number theorem. *)
3 (* ========================================================================= *)
5 needs "Library/prime.ml";;
6 needs "Library/pocklington.ml";;
7 needs "Library/analysis.ml";;
8 needs "Library/transc.ml";;
9 needs "Library/calc_real.ml";;
10 needs "Library/floor.ml";;
14 (* ------------------------------------------------------------------------- *)
15 (* A ridiculous ommission from the OCaml Num library. *)
16 (* ------------------------------------------------------------------------- *)
19 let p22 = Pervasives.( ** ) 2.0 22.0
20 and p44 = Pervasives.( ** ) 2.0 44.0
21 and p66 = Pervasives.( ** ) 2.0 66.0
22 and q22 = pow2 22 and q44 = pow2 44 and q66 = pow2 66 in
25 let u0 = int_of_float(y0 *. p22) in
26 let y1 = p22 *. y0 -. float_of_int u0 in
27 let u1 = int_of_float(y1 *. p22) in
28 let y2 = p22 *. y1 -. float_of_int u1 in
29 let u2 = int_of_float(y2 *. p22) in
30 let y3 = p22 *. y2 -. float_of_int u2 in
31 if y3 <> 0.0 then failwith "num_of_float: inexactness!" else
32 (Int u0 // q22 +/ Int u1 // q44 +/ Int u2 // q66) */ pow2 n;;
34 (* ------------------------------------------------------------------------- *)
35 (* Integer truncated square root *)
36 (* ------------------------------------------------------------------------- *)
38 let ISQRT = new_definition
39 `ISQRT n = @m. m EXP 2 <= n /\ n < (m + 1) EXP 2`;;
41 let ISQRT_WORKS = prove
42 (`!n. ISQRT(n) EXP 2 <= n /\ n < (ISQRT(n) + 1) EXP 2`,
43 GEN_TAC THEN REWRITE_TAC[ISQRT] THEN CONV_TAC SELECT_CONV THEN
44 SUBGOAL_THEN `(?m. m EXP 2 <= n) /\ (?a. !m. m EXP 2 <= n ==> m <= a)`
47 ONCE_REWRITE_TAC[num_MAX] THEN
48 MATCH_MP_TAC MONO_EXISTS THEN
49 MESON_TAC[ARITH_RULE `~(m + 1 <= m)`; NOT_LE]] THEN
50 CONJ_TAC THENL [EXISTS_TAC `0` THEN REWRITE_TAC[ARITH; LE_0]; ALL_TAC] THEN
51 EXISTS_TAC `n:num` THEN X_GEN_TAC `m:num` THEN
52 MESON_TAC[LE_SQUARE_REFL; EXP_2; LE_TRANS]);;
56 MP_TAC(SPEC `0` ISQRT_WORKS) THEN
57 SIMP_TAC[ARITH_RULE `x <= 0 <=> (x = 0)`; EXP_EQ_0; ARITH_EQ]);;
59 let ISQRT_UNIQUE = prove
60 (`!m n. (ISQRT n = m) <=> m EXP 2 <= n /\ n < (m + 1) EXP 2`,
61 REPEAT GEN_TAC THEN EQ_TAC THEN MP_TAC (SPEC `n:num` ISQRT_WORKS) THENL
62 [MESON_TAC[]; ALL_TAC] THEN
64 SUBGOAL_THEN `(ISQRT n) EXP 2 < (m + 1) EXP 2 /\
65 m EXP 2 < (ISQRT n + 1) EXP 2`
67 [ASM_MESON_TAC[LT_SUC_LE; LE_SUC_LT; LET_TRANS; LTE_TRANS];
68 SIMP_TAC[num_CONV `2`; EXP_MONO_LT_SUC; GSYM LE_ANTISYM] THEN ARITH_TAC]);;
72 if ?m. SUC n = m EXP 2 then SUC(ISQRT n) else ISQRT n`,
73 GEN_TAC THEN REWRITE_TAC[ISQRT_UNIQUE] THEN COND_CASES_TAC THENL
75 ASM_MESON_TAC[ISQRT_WORKS; ARITH_RULE
76 `a <= n /\ n < b /\ ~(SUC n = a) /\ ~(SUC n = b)
77 ==> a <= SUC n /\ SUC n < b`]] THEN
80 MP_TAC(CONJUNCT2(SPEC `n:num` ISQRT_WORKS)) THEN
81 REWRITE_TAC[EXP_2; GSYM ADD1; MULT_CLAUSES; ADD_CLAUSES; LT_SUC] THEN
83 POP_ASSUM(X_CHOOSE_TAC `m:num`) THEN
84 SUBGOAL_THEN `m = SUC(ISQRT n)` SUBST_ALL_TAC THENL
85 [ALL_TAC; ASM_REWRITE_TAC[LE_REFL]] THEN
86 SUBGOAL_THEN `ISQRT(n) EXP 2 < m EXP 2 /\ m EXP 2 <= SUC(ISQRT n) EXP 2`
89 REWRITE_TAC[num_CONV `2`; EXP_MONO_LE_SUC; EXP_MONO_LT_SUC] THEN ARITH_TAC] THEN
90 MP_TAC(SPEC `n:num` ISQRT_WORKS) THEN REWRITE_TAC[ADD1] THEN
91 FIRST_X_ASSUM(SUBST1_TAC o SYM) THEN REWRITE_TAC[LT_SUC_LE; LE_SUC_LT]);;
93 (* ------------------------------------------------------------------------- *)
94 (* To allow us to deal with ln(2) numerically using standard conversion. *)
95 (* ------------------------------------------------------------------------- *)
97 let LN_2_COMPOSITION = prove
99 &7 * ln(&1 + inv(&8)) - &2 * ln(&1 + inv(&24)) - &4 * ln(&1 + inv(&80))`,
100 CONV_TAC(GEN_SIMPLIFY_CONV TOP_DEPTH_SQCONV (basic_ss []) 4
101 [GSYM LN_POW; GSYM LN_MUL; GSYM LN_DIV; REAL_POW_LT; real_div;
102 REAL_LT_ADD; REAL_LT_MUL; REAL_LT_INV_EQ; REAL_OF_NUM_LT; ARITH]) THEN
103 AP_TERM_TAC THEN CONV_TAC REAL_RAT_REDUCE_CONV);;
105 (* ------------------------------------------------------------------------- *)
106 (* Automatically process any ln(n) to allow us to use standard conversions. *)
107 (* ------------------------------------------------------------------------- *)
111 (`x = (&1 + inv(&8)) pow n * (x / (&1 + inv(&8)) pow n)`,
112 CONV_TAC REAL_RAT_REDUCE_CONV THEN
113 CONV_TAC SYM_CONV THEN MATCH_MP_TAC REAL_DIV_LMUL THEN
114 MATCH_MP_TAC REAL_POW_NZ THEN CONV_TAC REAL_RAT_REDUCE_CONV)
117 ==> (ln((&1 + inv(&8)) pow n * x / (&1 + inv(&8)) pow n) =
118 &n * ln(&1 + inv(&8)) + ln(&1 + (x / (&1 + inv(&8)) pow n - &1)))`,
119 REWRITE_TAC[REAL_ARITH `&1 + (x - &1) = x`] THEN
120 SIMP_TAC[LN_MUL; LN_POW; REAL_LT_DIV; REAL_POW_LT;
121 REAL_RAT_REDUCE_CONV `&0 < &1 + inv(&8)`])
122 and ln_tm = `ln` and x_tm = `x:real` and n_tm = `n:num` in
124 let ltm,tm = dest_comb tm0 in
125 if ltm <> ln_tm then failwith "expected ln(ratconst)" else
126 let x = rat_of_term tm in
128 let y' = y +/ y // Int 8 in
129 if y' </ x then dlog (n + 1) y' else n in
130 let n = dlog 0 (Int 1) in
131 let th1 = INST [mk_small_numeral n,n_tm; tm,x_tm] pth in
132 let th2 = AP_TERM ltm th1 in
133 let th3 = PART_MATCH (lhs o rand) qth (rand(concl th2)) in
134 let th4 = MP th3 (EQT_ELIM(REAL_RAT_REDUCE_CONV(lhand(concl th3)))) in
135 let th5 = TRANS th2 th4 in
136 CONV_RULE(funpow 4 RAND_CONV REAL_RAT_REDUCE_CONV) th5;;
138 (* ------------------------------------------------------------------------- *)
139 (* Coarser version subtracting off multiples of ln(2) first, then using it. *)
140 (* ------------------------------------------------------------------------- *)
144 (`x = &2 pow n * (x / &2 pow n)`,
145 CONV_TAC REAL_RAT_REDUCE_CONV THEN
146 CONV_TAC SYM_CONV THEN MATCH_MP_TAC REAL_DIV_LMUL THEN
147 MATCH_MP_TAC REAL_POW_NZ THEN CONV_TAC REAL_RAT_REDUCE_CONV)
150 ==> (ln(&2 pow n * x / &2 pow n) =
151 &n * ln(&2) + ln(&1 + (x / &2 pow n - &1)))`,
152 REWRITE_TAC[REAL_ARITH `&1 + (x - &1) = x`] THEN
153 SIMP_TAC[LN_MUL; LN_POW; REAL_LT_DIV; REAL_POW_LT;
154 REAL_RAT_REDUCE_CONV `&0 < &2`])
155 and ln_tm = `ln` and x_tm = `x:real` and n_tm = `n:num` in
157 let ltm,tm = dest_comb tm0 in
158 if ltm <> ln_tm then failwith "expected ln(ratconst)" else
159 let x = rat_of_term tm in
161 let y' = y */ Int 2 in
162 if y' </ x then dlog (n + 1) y' else n in
163 let n = dlog 0 (Int 1) in
164 let th1 = INST [mk_small_numeral n,n_tm; tm,x_tm] pth in
165 let th2 = AP_TERM ltm th1 in
166 let th3 = PART_MATCH (lhs o rand) qth (rand(concl th2)) in
167 let th4 = MP th3 (EQT_ELIM(REAL_RAT_REDUCE_CONV(lhand(concl th3)))) in
168 let th5 = TRANS th2 th4 in
169 let th6 = CONV_RULE(funpow 4 RAND_CONV REAL_RAT_REDUCE_CONV) th5 in
170 let th7 = CONV_RULE (funpow 3 RAND_CONV REAL_RAT_REDUCE_CONV) th6 in
171 CONV_RULE(RAND_CONV(ONCE_DEPTH_CONV LN_N_CONV)) th7;;
173 (* ------------------------------------------------------------------------- *)
174 (* Lemmas about floor and frac. *)
175 (* ------------------------------------------------------------------------- *)
177 let FLOOR_DOUBLE_NUM = prove
180 ==> &2 * floor(&n / &r) <= floor(&(2 * n + d) / &r) /\
181 floor(&(2 * n + d) / &r) <= &2 * floor(&n / &r) + &1`,
182 REPEAT GEN_TAC THEN STRIP_TAC THEN
183 SUBGOAL_THEN `floor(&n / &r) = floor((&n + &d / &2) / &r)` SUBST1_TAC THENL
185 REWRITE_TAC[GSYM REAL_OF_NUM_ADD; GSYM REAL_OF_NUM_MUL] THEN
186 SUBGOAL_THEN `&2 * &n + &d = &2 * (&n + &d / &2)` SUBST1_TAC THENL
187 [SIMP_TAC[REAL_ADD_LDISTRIB; REAL_DIV_LMUL; REAL_OF_NUM_EQ; ARITH_EQ];
189 REWRITE_TAC[GSYM REAL_ADD_LDISTRIB; GSYM REAL_MUL_ASSOC; real_div] THEN
190 REWRITE_TAC[GSYM real_div; FLOOR_DOUBLE]] THEN
191 CONV_TAC SYM_CONV THEN REWRITE_TAC[GSYM FLOOR_UNIQUE] THEN
192 MP_TAC(SPEC `&n / &r` FLOOR) THEN SIMP_TAC[] THEN REPEAT STRIP_TAC THENL
193 [MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&n / &r` THEN
194 ASM_REWRITE_TAC[] THEN
195 REWRITE_TAC[real_div; REAL_ADD_RDISTRIB; REAL_LE_ADDR] THEN
196 SIMP_TAC[REAL_LE_MUL; REAL_POS; REAL_LE_INV_EQ];
198 UNDISCH_TAC `&n / &r < floor (&n / &r) + &1` THEN
199 ASM_SIMP_TAC[REAL_LT_LDIV_EQ; REAL_OF_NUM_LT] THEN
200 SIMP_TAC[REAL_LT_INTEGERS; FLOOR; INTEGER_CLOSED] THEN
201 MATCH_MP_TAC(REAL_ARITH `b < a ==> n + a <= c ==> n + b < c`) THEN
202 ASM_SIMP_TAC[REAL_LT_LDIV_EQ; REAL_MUL_LID; REAL_OF_NUM_LT; ARITH]);;
204 (* ------------------------------------------------------------------------- *)
205 (* Range bounds on ln(n!). *)
206 (* ------------------------------------------------------------------------- *)
209 (`!n. ln(&(FACT n)) = sum(1,n) (\d. ln(&d))`,
210 INDUCT_TAC THEN REWRITE_TAC[FACT; sum; LN_1] THEN
211 SIMP_TAC[GSYM REAL_OF_NUM_MUL; LN_MUL; REAL_OF_NUM_LT; FACT_LT; LT_0] THEN
212 ASM_REWRITE_TAC[ADD1] THEN REWRITE_TAC[ADD_AC; REAL_ADD_AC]);;
214 let LN_FACT_BOUNDS = prove
215 (`!n. ~(n = 0) ==> abs(ln(&(FACT n)) - (&n * ln(&n) - &n)) <= &1 + ln(&n)`,
218 ==> ?z. &n < z /\ z < &(n + 1) /\
219 (&(n + 1) * ln(&(n + 1)) - &n * ln(&n) = ln(z) + &1)`
221 [REPEAT STRIP_TAC THEN
222 MP_TAC(SPECL [`\x. x * ln(x)`; `\x. ln(x) + &1`; `&n`; `&(n + 1)`]
224 REWRITE_TAC[GSYM REAL_OF_NUM_ADD] THEN
225 REWRITE_TAC[REAL_ARITH `(n + &1) - n = &1`] THEN
226 REWRITE_TAC[REAL_MUL_LID] THEN DISCH_THEN MATCH_MP_TAC THEN
227 REWRITE_TAC[REAL_ARITH `a < a + &1`] THEN
228 X_GEN_TAC `x:real` THEN STRIP_TAC THEN
229 MP_TAC(SPEC `x:real` (DIFF_CONV `\x. x * ln(x)`)) THEN
230 SIMP_TAC[REAL_MUL_LID; REAL_MUL_RID; REAL_MUL_LINV; REAL_LT_IMP_NZ] THEN
231 DISCH_THEN MATCH_MP_TAC THEN MATCH_MP_TAC REAL_LTE_TRANS THEN
232 EXISTS_TAC `&n` THEN ASM_REWRITE_TAC[REAL_OF_NUM_LT] THEN
233 UNDISCH_TAC `~(n = 0)` THEN ARITH_TAC;
235 REWRITE_TAC[RIGHT_IMP_EXISTS_THM; SKOLEM_THM] THEN
236 DISCH_THEN(X_CHOOSE_TAC `k:num->real`) THEN
238 `!n. &(n + 1) * ln(&(n + 1)) = sum(1,n) (\i. ln(k i) + &1)`
240 [INDUCT_TAC THEN REWRITE_TAC[NOT_SUC] THEN
241 REWRITE_TAC[sum; ADD_CLAUSES; LN_1; REAL_MUL_RZERO] THEN
242 FIRST_X_ASSUM(MP_TAC o SPEC `n + 1`) THEN
243 REWRITE_TAC[ADD_EQ_0; ARITH_EQ] THEN
244 REWRITE_TAC[ARITH_RULE `(n + 1) + 1 = n + 2`;
245 ARITH_RULE `SUC(n + 1) = n + 2`] THEN
246 DISCH_THEN(MP_TAC o last o CONJUNCTS) THEN
247 REWRITE_TAC[REAL_ARITH `(a - b = c) <=> (a = b + c)`] THEN
248 DISCH_THEN SUBST1_TAC THEN ASM_REWRITE_TAC[] THEN
251 REWRITE_TAC[SUM_ADD] THEN
252 CONV_TAC(LAND_CONV(BINDER_CONV(RAND_CONV(RAND_CONV(LAND_CONV
253 (LAND_CONV num_CONV)))))) THEN
254 REWRITE_TAC[ADD1; SUM_REINDEX; SUM_CONST] THEN
255 ONCE_REWRITE_TAC[REAL_ARITH `(a = b + c * &1) <=> (b = a - c)`] THEN
258 `!n. abs(sum(1,n+1) (\i. ln(&i)) - (&(n + 1) * ln (&(n + 1)) - &(n + 1)))
259 <= &1 + ln(&(n + 1))`
262 GEN_REWRITE_TAC (LAND_CONV o funpow 3 RAND_CONV)
263 [GSYM REAL_OF_NUM_ADD] THEN
264 MATCH_MP_TAC(REAL_ARITH
265 `abs(x - (y - z)) <= a ==> abs(x - (y - (z + &1))) <= &1 + a`) THEN
266 FIRST_ASSUM(fun th -> GEN_REWRITE_TAC
267 (LAND_CONV o RAND_CONV o RAND_CONV) [GSYM th]) THEN
269 `sum(1,n + 1) (\i. ln (&i)) = sum(1,n) (\i. ln(&(i + 1)))`
271 [GEN_REWRITE_TAC RAND_CONV [SUM_DIFF] THEN
272 REWRITE_TAC[SUM_1; ADD_CLAUSES; LN_1; REAL_SUB_RZERO] THEN
273 GEN_REWRITE_TAC (funpow 3 LAND_CONV) [SYM(NUM_REDUCE_CONV `0 + 1`)] THEN
274 REWRITE_TAC[SUM_REINDEX] THEN REWRITE_TAC[ADD_AC];
276 REWRITE_TAC[GSYM SUM_SUB] THEN
277 MATCH_MP_TAC REAL_LE_TRANS THEN
278 EXISTS_TAC `sum(1,n) (\n. abs(ln(&(n + 1)) - ln(k n)))` THEN
279 REWRITE_TAC[ABS_SUM] THEN
280 MATCH_MP_TAC REAL_LE_TRANS THEN
281 EXISTS_TAC `sum(1,n) (\i. ln(&(i + 1)) - ln(&i))` THEN CONJ_TAC THENL
282 [MATCH_MP_TAC SUM_LE THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
284 MATCH_MP_TAC(REAL_ARITH `a < b /\ b < c ==> abs(c - b) <= c - a`) THEN
285 SUBGOAL_THEN `&0 < &r /\ &r < k r /\ k r < &(r + 1)` MP_TAC THENL
286 [ALL_TAC; MESON_TAC[LN_MONO_LT; REAL_LT_TRANS]] THEN
287 ASM_SIMP_TAC[REAL_OF_NUM_LT; ARITH_RULE `0 < r <=> 1 <= r`;
288 ARITH_RULE `~(r = 0) <=> 1 <= r`];
290 REWRITE_TAC[SUM_SUB] THEN
291 REWRITE_TAC[GSYM(SPECL [`f:num->real`; `m:num`; `1`] SUM_REINDEX)] THEN
292 ONCE_REWRITE_TAC[SUM_DIFF] THEN
293 REWRITE_TAC[ARITH; SUM_2; SUM_1; LN_1; REAL_ADD_RID] THEN
294 ONCE_REWRITE_TAC[ARITH_RULE `2 + n = SUC(1 + n)`] THEN
295 REWRITE_TAC[sum; ADD_CLAUSES] THEN
296 REWRITE_TAC[ADD_AC] THEN
297 REWRITE_TAC[REAL_ARITH `(a + b) - c - (a - c) = b`; REAL_LE_REFL];
299 INDUCT_TAC THEN REWRITE_TAC[NOT_SUC] THEN
300 ASM_REWRITE_TAC[ADD1; LN_FACT]);;
302 (* ------------------------------------------------------------------------- *)
303 (* Some extra number-theoretic odds and ends are useful. *)
304 (* ------------------------------------------------------------------------- *)
306 let primepow = new_definition
307 `primepow q <=> ?p k. 1 <= k /\ prime p /\ (q = p EXP k)`;;
309 let aprimedivisor = new_definition
310 `aprimedivisor q = @p. prime p /\ p divides q`;;
312 let PRIMEPOW_GE_2 = prove
313 (`!q. primepow q ==> 2 <= q`,
314 REWRITE_TAC[primepow; LEFT_IMP_EXISTS_THM] THEN
315 MAP_EVERY X_GEN_TAC [`q:num`; `p:num`; `k:num`] THEN
316 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
317 DISCH_THEN SUBST1_TAC THEN MATCH_MP_TAC LE_TRANS THEN EXISTS_TAC `p:num` THEN
318 ASM_SIMP_TAC[PRIME_GE_2] THEN GEN_REWRITE_TAC LAND_CONV [GSYM EXP_1] THEN
319 REWRITE_TAC[LE_EXP] THEN COND_CASES_TAC THEN ASM_REWRITE_TAC[ARITH]);;
321 let PRIMEPOW_0 = prove
323 MESON_TAC[NUM_REDUCE_CONV `2 <= 0`; PRIMEPOW_GE_2]);;
325 let APRIMEDIVISOR_PRIMEPOW = prove
326 (`!p k. prime p /\ 1 <= k ==> (aprimedivisor(p EXP k) = p)`,
327 REPEAT STRIP_TAC THEN REWRITE_TAC[aprimedivisor] THEN
328 MATCH_MP_TAC SELECT_UNIQUE THEN REWRITE_TAC[] THEN
329 X_GEN_TAC `q:num` THEN
330 FIRST_ASSUM(SUBST1_TAC o MATCH_MP (ARITH_RULE
331 `1 <= k ==> (k = SUC(k - 1))`)) THEN
332 REWRITE_TAC[EXP] THEN
333 ASM_MESON_TAC[DIVIDES_REFL; DIVIDES_RMUL; PRIME_DIVEXP; PRIME_DIVPROD;
336 let APRIMEDIVISOR = prove
337 (`!n. ~(n = 1) ==> prime(aprimedivisor n) /\ (aprimedivisor n) divides n`,
338 GEN_TAC THEN DISCH_TAC THEN REWRITE_TAC[aprimedivisor] THEN
339 CONV_TAC SELECT_CONV THEN ASM_SIMP_TAC[PRIME_FACTOR]);;
341 let BIG_POWER_LEMMA = prove
342 (`!m n. 2 <= m ==> ?k. n <= m EXP k`,
343 REPEAT STRIP_TAC THEN EXISTS_TAC `SUC n` THEN
344 MATCH_MP_TAC LE_TRANS THEN EXISTS_TAC `2 EXP (SUC n)` THEN
345 ASM_REWRITE_TAC[EXP_MONO_LE_SUC] THEN
346 SPEC_TAC(`n:num`,`n:num`) THEN INDUCT_TAC THEN
347 REWRITE_TAC[EXP; ARITH] THEN
348 UNDISCH_TAC `n <= 2 EXP SUC n` THEN REWRITE_TAC[EXP] THEN
349 MP_TAC(SPECL [`2:num`; `n:num`] EXP_EQ_0) THEN
350 REWRITE_TAC[ARITH] THEN SPEC_TAC(`2 EXP n`,`m:num`) THEN ARITH_TAC);;
352 let PRIME_PRIMEPOW = prove
353 (`!p. prime p ==> primepow p`,
354 MESON_TAC[prime; primepow; LE_REFL; EXP_1]);;
356 (* ------------------------------------------------------------------------- *)
357 (* Derive Bezout-type identity by finding gcd. *)
358 (* ------------------------------------------------------------------------- *)
360 let rec bezout (m,n) =
361 if m =/ Int 0 then (Int 0,Int 1) else if n =/ Int 0 then (Int 1,Int 0)
363 let q = quo_num n m and r = mod_num n m in
364 let (x,y) = bezout(m,r) in
366 else let (x,y) = bezout(n,m) in (y,x);;
368 (* ------------------------------------------------------------------------- *)
369 (* Conversion for "primepow" applied to particular numeral. *)
370 (* ------------------------------------------------------------------------- *)
375 REWRITE_TAC[primepow] THEN MESON_TAC[EXP_EQ_0; PRIME_0])
378 REWRITE_TAC[primepow] THEN
379 MESON_TAC[EXP_EQ_1; PRIME_1; NUM_REDUCE_CONV `1 <= 0`])
381 (`prime p ==> 1 <= k /\ (q = p EXP k) ==> (primepow q <=> T)`,
384 (`(p * x = r * y + 1) /\ ~(p = 1) /\ ~(r = 1) /\ (q = p * r * d)
385 ==> (primepow q <=> F)`,
386 REPEAT STRIP_TAC THEN REWRITE_TAC[primepow] THEN
387 DISCH_THEN(X_CHOOSE_THEN `P:num` MP_TAC) THEN
388 DISCH_THEN(X_CHOOSE_THEN `k:num` MP_TAC) THEN
389 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
390 DISCH_THEN SUBST_ALL_TAC THEN
391 MP_TAC(SPEC `r:num` PRIME_FACTOR) THEN
392 MP_TAC(SPEC `p:num` PRIME_FACTOR) THEN
393 ASM_REWRITE_TAC[] THEN
394 DISCH_THEN(X_CHOOSE_THEN `P_p:num` MP_TAC) THEN
395 REWRITE_TAC[divides] THEN
396 DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC) THEN
397 DISCH_THEN(X_CHOOSE_THEN `d_p:num` SUBST_ALL_TAC) THEN
398 DISCH_THEN(X_CHOOSE_THEN `P_r:num` MP_TAC) THEN
399 DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC) THEN
400 DISCH_THEN(X_CHOOSE_THEN `d_r:num` SUBST_ALL_TAC) THEN
401 SUBGOAL_THEN `P_p divides P /\ P_r divides P` ASSUME_TAC THENL
402 [CONJ_TAC THEN MATCH_MP_TAC PRIME_DIVEXP THEN EXISTS_TAC `k:num` THEN
403 ASM_MESON_TAC[divides; MULT_AC]; ALL_TAC] THEN
404 SUBGOAL_THEN `(P_p = P) /\ (P_r = P:num)` (CONJUNCTS_THEN SUBST_ALL_TAC)
405 THENL [ASM_MESON_TAC[prime]; ALL_TAC] THEN
406 ASM_MESON_TAC[DIVIDES_ADD_REVR; divides; MULT_AC; DIVIDES_ONE; prime])
407 and p_tm = `p:num` and k_tm = `k:num` and q_tm = `q:num`
408 and r_tm = `r:num` and d_tm = `d:num`
409 and x_tm = `x:num` and y_tm = `y:num` and primepow_tm = `primepow` in
411 let ptm,tm = dest_comb tm0 in
412 if ptm <> primepow_tm then failwith "expected primepow(numeral)" else
413 let q = dest_numeral tm in
414 if q =/ Int 0 then pth0
415 else if q =/ Int 1 then pth1 else
417 [] -> failwith "internal failure in PRIMEPOW_CONV"
418 | [p,k] -> let th1 = INST [mk_numeral q,q_tm;
420 mk_numeral k,k_tm] pth2 in
421 let th2 = MP th1 (EQT_ELIM(PRIME_CONV(lhand(concl th1)))) in
422 MP th2 (EQT_ELIM(NUM_REDUCE_CONV(lhand(concl th2))))
424 let d = q // (p */ r) in
425 let (x,y) = bezout(p,r) in
427 if x </ Int 0 then r,p,y,minus_num x
428 else p,r,x,minus_num y in
429 let th1 = INST [mk_numeral q,q_tm;
434 mk_numeral d,d_tm] pth3 in
435 MP th1 (EQT_ELIM(NUM_REDUCE_CONV(lhand(concl th1))));;
437 (* ------------------------------------------------------------------------- *)
438 (* Conversion for "aprimedivisor" applied to prime power (only). *)
439 (* ------------------------------------------------------------------------- *)
441 let APRIMEDIVISOR_CONV =
443 (`prime p ==> 1 <= k /\ (q = p EXP k) ==> (aprimedivisor q = p)`,
444 MESON_TAC[APRIMEDIVISOR_PRIMEPOW])
445 and p_tm = `p:num` and k_tm = `k:num` and q_tm = `q:num`
446 and aprimedivisor_tm = `aprimedivisor` in
448 let ptm,tm = dest_comb tm0 in
449 if ptm <> aprimedivisor_tm then failwith "expected primepow(numeral)" else
450 let q = dest_numeral tm in
451 if q =/ Int 0 then failwith "APRIMEDIVISOR_CONV: not a prime power" else
453 [p,k] -> let th1 = INST [mk_numeral q,q_tm;
455 mk_numeral k,k_tm] pth in
456 let th2 = MP th1 (EQT_ELIM(PRIME_CONV(lhand(concl th1)))) in
457 MP th2 (EQT_ELIM(NUM_REDUCE_CONV(lhand(concl th2))))
458 | _ -> failwith "APRIMEDIVISOR_CONV: not a prime power";;
460 (* ------------------------------------------------------------------------- *)
461 (* The Mangoldt function. *)
462 (* ------------------------------------------------------------------------- *)
464 let mangoldt = new_definition
465 `mangoldt d = if primepow d then ln(&(aprimedivisor d)) else &0`;;
467 let MANGOLDT_POS = prove
468 (`!d. &0 <= mangoldt d`,
469 GEN_TAC THEN REWRITE_TAC[mangoldt] THEN
470 COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
471 ASM_MESON_TAC[APRIMEDIVISOR_PRIMEPOW; ARITH_RULE `2 <= a ==> 1 <= a`;
472 PRIME_GE_2; LN_POS; REAL_OF_NUM_LE; primepow]);;
474 (* ------------------------------------------------------------------------- *)
476 (* ------------------------------------------------------------------------- *)
478 let LN_PRIMEFACT = prove
481 sum(1,n) (\d. if primepow d /\ d divides n
482 then ln(&(aprimedivisor d)) else &0))`,
483 MATCH_MP_TAC num_WF THEN X_GEN_TAC `n:num` THEN REPEAT STRIP_TAC THEN
484 ASM_CASES_TAC `n = 1` THENL
485 [MATCH_MP_TAC EQ_TRANS THEN
486 EXISTS_TAC `sum(1,n) (\d. &0)` THEN CONJ_TAC THENL
487 [ASM_REWRITE_TAC[SUM_0; LN_1]; ALL_TAC] THEN
488 MATCH_MP_TAC SUM_EQ THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
489 REWRITE_TAC[] THEN COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
490 ASM_MESON_TAC[PRIMEPOW_GE_2; DIVIDES_LE; NUM_REDUCE_CONV `2 <= 1`;
493 FIRST_ASSUM(MP_TAC o MATCH_MP PRIME_FACTOR) THEN
494 DISCH_THEN(X_CHOOSE_THEN `p:num` MP_TAC) THEN
495 DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC) THEN
496 GEN_REWRITE_TAC LAND_CONV [divides] THEN
497 DISCH_THEN(X_CHOOSE_THEN `m:num` SUBST_ALL_TAC) THEN
498 FIRST_X_ASSUM(MP_TAC o SPEC `m:num`) THEN
499 RULE_ASSUM_TAC(REWRITE_RULE[MULT_EQ_0; DE_MORGAN_THM]) THEN
501 [ONCE_REWRITE_TAC[ARITH_RULE `m < p * m <=> 1 * m < p * m`] THEN
502 SIMP_TAC[LT_MULT_RCANCEL; ARITH_RULE `1 < p <=> 2 <= p`] THEN
503 ASM_SIMP_TAC[PRIME_GE_2];
505 ASM_REWRITE_TAC[] THEN
506 REWRITE_TAC[GSYM REAL_OF_NUM_MUL] THEN
507 ASM_SIMP_TAC[LN_MUL; REAL_OF_NUM_LT; ARITH_RULE `0 < n <=> ~(n = 0)`] THEN
508 DISCH_THEN(K ALL_TAC) THEN
509 SUBGOAL_THEN `?k. 1 <= k /\ (p EXP k) divides (p * m)` MP_TAC THENL
510 [EXISTS_TAC `1` THEN SIMP_TAC[EXP_1; DIVIDES_RMUL; DIVIDES_REFL; LE_REFL];
512 SUBGOAL_THEN `?k. !j. 1 <= j /\ (p EXP j) divides (p * m) ==> j <= k`
514 [MP_TAC(SPECL [`p:num`; `p * m:num`] BIG_POWER_LEMMA) THEN
515 ASM_SIMP_TAC[PRIME_GE_2] THEN
516 MATCH_MP_TAC MONO_EXISTS THEN X_GEN_TAC `k:num` THEN
517 REPEAT STRIP_TAC THEN
518 FIRST_X_ASSUM(MP_TAC o MATCH_MP DIVIDES_LE) THEN
519 ASM_REWRITE_TAC[MULT_EQ_0] THEN
520 ONCE_REWRITE_TAC[GSYM CONTRAPOS_THM] THEN REWRITE_TAC[NOT_LE] THEN
521 DISCH_TAC THEN MATCH_MP_TAC LET_TRANS THEN EXISTS_TAC `p EXP k` THEN
522 ASM_REWRITE_TAC[LT_EXP] THEN ASM_SIMP_TAC[PRIME_GE_2];
524 GEN_REWRITE_TAC I [TAUT `a ==> b ==> c <=> b /\ a ==> c`] THEN
525 GEN_REWRITE_TAC LAND_CONV [num_MAX] THEN
526 DISCH_THEN(X_CHOOSE_THEN `k:num` STRIP_ASSUME_TAC) THEN
529 (\d. if primepow d /\ d divides m then ln (&(aprimedivisor d)) else &0) =
531 (\d. if primepow d /\ d divides m then ln (&(aprimedivisor d)) else &0)`
533 [ONCE_REWRITE_TAC[SUM_DIFF] THEN
534 AP_THM_TAC THEN AP_TERM_TAC THEN
535 SUBGOAL_THEN `1 + p * m = (1 + m) + (p * m - m)` SUBST1_TAC THENL
536 [MATCH_MP_TAC(ARITH_RULE
537 `1 * y <= x ==> (1 + x = (1 + y) + (x - y))`) THEN
538 SIMP_TAC[LE_MULT_RCANCEL] THEN
539 ASM_MESON_TAC[PRIME_GE_2; ARITH_RULE `2 <= p ==> 1 <= p`];
541 GEN_REWRITE_TAC RAND_CONV [GSYM SUM_TWO] THEN
542 MATCH_MP_TAC(REAL_ARITH `(b = &0) ==> (a = a + b)`) THEN
545 ==> ((if primepow d /\ d divides m then ln (&(aprimedivisor d))
548 [X_GEN_TAC `d:num` THEN REWRITE_TAC[GE] THEN DISCH_TAC THEN
549 COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
550 ASM_MESON_TAC[DIVIDES_LE; ARITH_RULE `~(1 + m <= d /\ d <= m)`];
552 DISCH_THEN(MP_TAC o MATCH_MP SUM_ZERO) THEN DISCH_THEN MATCH_MP_TAC THEN
555 ONCE_REWRITE_TAC[SUM_DIFF] THEN REWRITE_TAC[SUM_1] THEN
556 REWRITE_TAC[PRIMEPOW_0; REAL_SUB_RZERO] THEN
557 SUBGOAL_THEN `1 + p * m = p EXP k + 1 + (p * m - p EXP k)` SUBST1_TAC THENL
558 [MATCH_MP_TAC(ARITH_RULE `k <= p ==> (1 + p = k + 1 + (p - k))`) THEN
559 ASM_MESON_TAC[DIVIDES_LE; MULT_EQ_0];
561 REWRITE_TAC[GSYM SUM_TWO] THEN
562 MATCH_MP_TAC(REAL_ARITH
563 `(a = a') /\ (l + b = c) ==> (l + a + b = a' + c)`) THEN
565 [MATCH_MP_TAC SUM_EQ THEN
566 X_GEN_TAC `d:num` THEN REWRITE_TAC[ADD_CLAUSES; LE_0] THEN STRIP_TAC THEN
567 ASM_CASES_TAC `primepow d` THEN ASM_REWRITE_TAC[] THEN
568 SUBGOAL_THEN `d divides (p * m) <=> d divides m`
569 (fun th -> REWRITE_TAC[th]) THEN
570 UNDISCH_TAC `primepow d` THEN REWRITE_TAC[primepow] THEN
571 DISCH_THEN(X_CHOOSE_THEN `q:num` MP_TAC) THEN
572 DISCH_THEN(X_CHOOSE_THEN `j:num` MP_TAC) THEN
573 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
574 DISCH_THEN SUBST_ALL_TAC THEN ASM_CASES_TAC `q = p:num` THENL
575 [FIRST_X_ASSUM SUBST_ALL_TAC THEN
576 MATCH_MP_TAC(TAUT `(b ==> a) /\ b ==> (a <=> b)`) THEN
577 REWRITE_TAC[DIVIDES_LMUL] THEN
578 MATCH_MP_TAC DIVIDES_TRANS THEN
579 EXISTS_TAC `p EXP (k - 1)` THEN CONJ_TAC THENL
580 [REWRITE_TAC[divides] THEN EXISTS_TAC `p EXP ((k - 1) - j)` THEN
581 REWRITE_TAC[GSYM EXP_ADD] THEN AP_TERM_TAC THEN
582 UNDISCH_TAC `p EXP j < p EXP k` THEN ASM_REWRITE_TAC[LT_EXP] THEN
585 UNDISCH_TAC `p EXP k divides (p * m)` THEN
586 FIRST_ASSUM((fun th -> GEN_REWRITE_TAC (funpow 2 LAND_CONV o RAND_CONV)
588 (ARITH_RULE `1 <= k ==> (k = SUC(k - 1))`)) THEN
589 REWRITE_TAC[divides; EXP] THEN MATCH_MP_TAC MONO_EXISTS THEN
590 SIMP_TAC[GSYM MULT_ASSOC; EQ_MULT_LCANCEL] THEN
593 EQ_TAC THEN REWRITE_TAC[DIVIDES_LMUL] THEN
594 REWRITE_TAC[divides] THEN DISCH_THEN(X_CHOOSE_THEN `r:num` MP_TAC) THEN
595 DISCH_THEN(fun th -> ASSUME_TAC th THEN
596 MP_TAC(AP_TERM `(divides) p` th)) THEN
597 SIMP_TAC[DIVIDES_RMUL; DIVIDES_REFL] THEN DISCH_TAC THEN
598 SUBGOAL_THEN `p divides (q EXP j) \/ p divides r` MP_TAC THENL
599 [ASM_MESON_TAC[PRIME_DIVPROD]; ALL_TAC] THEN
600 DISCH_THEN DISJ_CASES_TAC THENL
601 [SUBGOAL_THEN `p divides q` MP_TAC THENL
602 [ASM_MESON_TAC[PRIME_DIVEXP]; ALL_TAC] THEN
603 ASM_MESON_TAC[prime; PRIME_1];
605 UNDISCH_TAC `p * m = q EXP j * r` THEN
606 UNDISCH_TAC `p divides r` THEN
607 REWRITE_TAC[divides] THEN DISCH_THEN(CHOOSE_THEN SUBST1_TAC) THEN
608 ONCE_REWRITE_TAC[ARITH_RULE `a * b * c = b * a * c:num`] THEN
609 SIMP_TAC[EQ_MULT_LCANCEL] THEN ASM_MESON_TAC[];
611 ONCE_REWRITE_TAC[GSYM SUM_SPLIT] THEN REWRITE_TAC[SUM_1] THEN
612 REWRITE_TAC[REAL_ADD_ASSOC] THEN BINOP_TAC THENL
613 [SUBGOAL_THEN `primepow (p EXP k)` ASSUME_TAC THENL
614 [ASM_MESON_TAC[primepow]; ALL_TAC] THEN
615 ASM_REWRITE_TAC[] THEN
616 SUBGOAL_THEN `~((p EXP k) divides m)` ASSUME_TAC THENL
617 [REWRITE_TAC[divides] THEN
618 DISCH_THEN(X_CHOOSE_THEN `r:num` SUBST_ALL_TAC) THEN
619 MP_TAC(ARITH_RULE `~(k + 1 <= k)`) THEN REWRITE_TAC[] THEN
620 FIRST_ASSUM MATCH_MP_TAC THEN
621 REWRITE_TAC[ARITH_RULE `1 <= k + 1`] THEN
622 ONCE_REWRITE_TAC[ADD_SYM] THEN REWRITE_TAC[EXP_ADD; EXP_1] THEN
623 MESON_TAC[MULT_ASSOC; DIVIDES_REFL; DIVIDES_RMUL];
625 ASM_REWRITE_TAC[REAL_ADD_RID] THEN AP_TERM_TAC THEN AP_TERM_TAC THEN
626 ASM_MESON_TAC[APRIMEDIVISOR_PRIMEPOW];
628 MATCH_MP_TAC SUM_EQ THEN
629 X_GEN_TAC `d:num` THEN REWRITE_TAC[ADD_CLAUSES; LE_0] THEN STRIP_TAC THEN
630 ASM_CASES_TAC `primepow d` THEN ASM_REWRITE_TAC[] THEN
631 SUBGOAL_THEN `d divides (p * m) <=> d divides m`
632 (fun th -> REWRITE_TAC[th]) THEN
633 UNDISCH_TAC `primepow d` THEN REWRITE_TAC[primepow] THEN
634 DISCH_THEN(X_CHOOSE_THEN `q:num` MP_TAC) THEN
635 DISCH_THEN(X_CHOOSE_THEN `j:num` MP_TAC) THEN
636 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
637 ASM_CASES_TAC `q = p:num` THENL
638 [UNDISCH_THEN `q = p:num` SUBST_ALL_TAC THEN
639 DISCH_THEN SUBST_ALL_TAC THEN
640 MATCH_MP_TAC(TAUT `(b ==> a) /\ ~a ==> (a <=> b)`) THEN
641 REWRITE_TAC[DIVIDES_LMUL] THEN DISCH_TAC THEN
642 FIRST_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE `a + 1 <= b ==> a < b`)) THEN
643 REWRITE_TAC[LT_EXP] THEN ASM_SIMP_TAC[PRIME_GE_2; NOT_LT];
645 DISCH_THEN SUBST_ALL_TAC THEN EQ_TAC THEN REWRITE_TAC[DIVIDES_LMUL] THEN
646 REWRITE_TAC[divides] THEN DISCH_THEN(X_CHOOSE_THEN `r:num` MP_TAC) THEN
647 DISCH_THEN(fun th -> ASSUME_TAC th THEN
648 MP_TAC(AP_TERM `(divides) p` th)) THEN
649 SIMP_TAC[DIVIDES_RMUL; DIVIDES_REFL] THEN DISCH_TAC THEN
650 SUBGOAL_THEN `p divides (q EXP j) \/ p divides r` MP_TAC THENL
651 [ASM_MESON_TAC[PRIME_DIVPROD]; ALL_TAC] THEN
652 DISCH_THEN DISJ_CASES_TAC THENL
653 [SUBGOAL_THEN `p divides q` MP_TAC THENL
654 [ASM_MESON_TAC[PRIME_DIVEXP]; ALL_TAC] THEN
655 ASM_MESON_TAC[prime; PRIME_1];
657 UNDISCH_TAC `p * m = q EXP j * r` THEN
658 UNDISCH_TAC `p divides r` THEN
659 REWRITE_TAC[divides] THEN DISCH_THEN(CHOOSE_THEN SUBST1_TAC) THEN
660 ONCE_REWRITE_TAC[ARITH_RULE `a * b * c = b * a * c:num`] THEN
661 SIMP_TAC[EQ_MULT_LCANCEL] THEN ASM_MESON_TAC[]);;
663 (* ------------------------------------------------------------------------- *)
664 (* The key expansion using the Mangoldt function. *)
665 (* ------------------------------------------------------------------------- *)
668 (`!n. ln(&(FACT n)) = sum(1,n) (\d. mangoldt(d) * floor(&n / &d))`,
669 GEN_TAC THEN REWRITE_TAC[LN_FACT] THEN MATCH_MP_TAC EQ_TRANS THEN
671 `sum(1,n) (\m. sum(1,n) (\d. if primepow d /\ d divides m
672 then ln (&(aprimedivisor d))
675 [MATCH_MP_TAC SUM_EQ THEN X_GEN_TAC `d:num` THEN STRIP_TAC THEN
676 ASM_SIMP_TAC[LN_PRIMEFACT; ARITH_RULE `~(n = 0) <=> 1 <= n`] THEN
677 FIRST_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE
678 `d < n + 1 ==> (n = d + (n - d))`)) THEN
680 GEN_REWRITE_TAC (RAND_CONV o LAND_CONV o RAND_CONV) [th]) THEN
681 REWRITE_TAC[GSYM SUM_SPLIT] THEN
682 REWRITE_TAC[REAL_ARITH `(a = a + b) <=> (b = &0)`] THEN
683 MATCH_MP_TAC EQ_TRANS THEN
684 EXISTS_TAC `sum(1 + d,n - d) (\k. &0)` THEN CONJ_TAC THENL
685 [ALL_TAC; REWRITE_TAC[SUM_0]] THEN
686 MATCH_MP_TAC SUM_EQ THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
687 REWRITE_TAC[] THEN COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
688 ASM_MESON_TAC[DIVIDES_LE; ARITH_RULE
689 `1 <= d /\ 1 + d <= r /\ (r <= d \/ (d = 0)) ==> F`];
691 ONCE_REWRITE_TAC[SUM_SWAP] THEN MATCH_MP_TAC SUM_EQ THEN
692 X_GEN_TAC `d:num` THEN STRIP_TAC THEN REWRITE_TAC[] THEN
693 REWRITE_TAC[mangoldt] THEN
694 ASM_CASES_TAC `primepow d` THEN ASM_REWRITE_TAC[SUM_0; REAL_MUL_LZERO] THEN
695 FIRST_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE `1 <= d ==> ~(d = 0)`)) THEN
696 DISCH_THEN(MP_TAC o MATCH_MP DIVISION) THEN
697 DISCH_THEN(MP_TAC o SPEC `n:num`) THEN
698 MAP_EVERY ABBREV_TAC [`q = n DIV d`; `r = n MOD d`] THEN
699 DISCH_THEN(CONJUNCTS_THEN2 SUBST_ALL_TAC ASSUME_TAC) THEN
700 SUBGOAL_THEN `floor (&(q * d + r) / &d) = &q` SUBST1_TAC THENL
701 [ONCE_REWRITE_TAC[GSYM FLOOR_UNIQUE] THEN
702 REWRITE_TAC[INTEGER_CLOSED] THEN
703 ASM_SIMP_TAC[REAL_LE_RDIV_EQ; REAL_LT_LDIV_EQ;
704 REAL_OF_NUM_LT; ARITH_RULE `0 < d <=> 1 <= d`] THEN
705 REWRITE_TAC[REAL_OF_NUM_ADD; REAL_OF_NUM_MUL] THEN
706 REWRITE_TAC[REAL_OF_NUM_LE; REAL_OF_NUM_LT] THEN
707 UNDISCH_TAC `r < d:num` THEN ARITH_TAC;
709 ONCE_REWRITE_TAC[GSYM SUM_SPLIT] THEN
710 MATCH_MP_TAC(REAL_ARITH `(b = &0) /\ (a = c) ==> (a + b = c)`) THEN
712 [MATCH_MP_TAC EQ_TRANS THEN EXISTS_TAC `sum(1 + q * d,r) (\x. &0)` THEN
713 CONJ_TAC THENL [ALL_TAC; REWRITE_TAC[SUM_0]] THEN
714 MATCH_MP_TAC SUM_EQ THEN REWRITE_TAC[] THEN
715 X_GEN_TAC `s:num` THEN STRIP_TAC THEN
716 COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
717 UNDISCH_TAC `d divides s` THEN REWRITE_TAC[divides] THEN
718 DISCH_THEN(X_CHOOSE_THEN `t:num` SUBST_ALL_TAC) THEN
719 FIRST_X_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE
720 `1 + x <= y * z ==> x < z * y`)) THEN
721 ASM_SIMP_TAC[LT_MULT_RCANCEL; ARITH_RULE `1 <= d ==> ~(d = 0)`] THEN
722 REWRITE_TAC[LT_EXISTS] THEN
723 DISCH_THEN(X_CHOOSE_THEN `e:num` SUBST_ALL_TAC) THEN
724 UNDISCH_TAC `d * (q + SUC e) < r + 1 + q * d` THEN
725 ONCE_REWRITE_TAC[GSYM CONTRAPOS_THM] THEN DISCH_TAC THEN
726 REWRITE_TAC[LEFT_ADD_DISTRIB; MULT_CLAUSES; GSYM ADD_ASSOC] THEN
727 REWRITE_TAC[ARITH_RULE `d * q + x < y + 1 + q * d <=> x <= y`] THEN
728 DISCH_THEN(MP_TAC o MATCH_MP (ARITH_RULE `a + b <= c ==> a <= c:num`)) THEN
729 ASM_REWRITE_TAC[NOT_LE];
731 ONCE_REWRITE_TAC[SUM_DIFF] THEN ONCE_REWRITE_TAC[ADD_SYM] THEN
732 REWRITE_TAC[GSYM SUM_TWO] THEN
733 SIMP_TAC[SUM_1; DIVIDES_0; DIVIDES_LMUL; DIVIDES_REFL] THEN
734 REWRITE_TAC[REAL_ARITH `(a + b) - b = a`] THEN
735 REWRITE_TAC[GSYM SUM_GROUP] THEN
736 MATCH_MP_TAC EQ_TRANS THEN
737 EXISTS_TAC `sum(0,q) (\x. ln (&(aprimedivisor d)))` THEN CONJ_TAC THENL
738 [ALL_TAC; REWRITE_TAC[SUM_CONST; REAL_MUL_AC]] THEN
739 MATCH_MP_TAC SUM_EQ THEN X_GEN_TAC `m:num` THEN STRIP_TAC THEN
741 FIRST_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE
742 `1 <= d ==> (d = 1 + (d - 1))`)) THEN
743 DISCH_THEN(fun th -> GEN_REWRITE_TAC
744 (funpow 2 LAND_CONV o RAND_CONV) [th]) THEN
745 REWRITE_TAC[GSYM SUM_SPLIT; SUM_1] THEN
746 SIMP_TAC[DIVIDES_LMUL; DIVIDES_REFL] THEN
747 MATCH_MP_TAC(REAL_ARITH `(b = &0) ==> (a + b = a)`) THEN
748 MATCH_MP_TAC EQ_TRANS THEN
749 EXISTS_TAC `sum(m * d + 1,d - 1) (\x. &0)` THEN CONJ_TAC THENL
750 [ALL_TAC; REWRITE_TAC[SUM_0]] THEN
751 MATCH_MP_TAC SUM_EQ THEN X_GEN_TAC `s:num` THEN
752 DISCH_THEN(CONJUNCTS_THEN2 MP_TAC ASSUME_TAC) THEN
753 GEN_REWRITE_TAC LAND_CONV [LE_EXISTS] THEN
754 REWRITE_TAC[] THEN ONCE_REWRITE_TAC[ADD_SYM] THEN
755 DISCH_THEN(X_CHOOSE_THEN `t:num` SUBST_ALL_TAC) THEN
756 COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
757 SUBGOAL_THEN `~(d divides (t + 1))` MP_TAC THENL
758 [DISCH_THEN(MP_TAC o MATCH_MP DIVIDES_LE) THEN
759 UNDISCH_TAC `t + m * d + 1 < d - 1 + m * d + 1` THEN
760 REWRITE_TAC[LT_ADD_RCANCEL] THEN
761 UNDISCH_TAC `d divides (t + m * d + 1)` THEN
762 ASM_CASES_TAC `t = 0` THEN ASM_REWRITE_TAC[ADD_CLAUSES] THENL
763 [ASM_MESON_TAC[DIVIDES_REFL; DIVIDES_LMUL; DIVIDES_ADD_REVR;
764 DIVIDES_ONE; PRIMEPOW_GE_2; NUM_REDUCE_CONV `2 <= 1`];
765 DISCH_TAC THEN ARITH_TAC];
767 UNDISCH_TAC `d divides (t + m * d + 1)` THEN
768 ONCE_REWRITE_TAC[ARITH_RULE `t + m * d + 1 = (t + 1) + m * d`] THEN
769 MESON_TAC[DIVIDES_REFL; DIVIDES_LMUL; DIVIDES_ADD_REVL]);;
771 (* ------------------------------------------------------------------------- *)
772 (* The Chebyshev psi function. *)
773 (* ------------------------------------------------------------------------- *)
775 let psi = new_definition
776 `psi(n) = sum(1,n) (\d. mangoldt(d))`;;
778 (* ------------------------------------------------------------------------- *)
779 (* The key bounds on the psi function. *)
780 (* ------------------------------------------------------------------------- *)
782 let PSI_BOUNDS_LN_FACT = prove
783 (`!n. ln(&(FACT(n))) - &2 * ln(&(FACT(n DIV 2))) <= psi(n) /\
784 psi(n) - psi(n DIV 2) <= ln(&(FACT(n))) - &2 * ln(&(FACT(n DIV 2)))`,
785 X_GEN_TAC `k:num` THEN MP_TAC(SPECL [`k:num`; `2`] DIVISION) THEN
786 REWRITE_TAC[ARITH_EQ] THEN
787 MAP_EVERY ABBREV_TAC [`n = k DIV 2`; `d = k MOD 2`] THEN
788 POP_ASSUM_LIST(K ALL_TAC) THEN ONCE_REWRITE_TAC[MULT_SYM] THEN
789 DISCH_THEN(CONJUNCTS_THEN2 SUBST1_TAC ASSUME_TAC) THEN
790 REWRITE_TAC[psi; MANGOLDT] THEN
792 `sum (1,n) (\d. mangoldt d * floor (&n / &d)) =
793 sum (1,2 * n + d) (\d. mangoldt d * floor (&n / &d))`
795 [REWRITE_TAC[ARITH_RULE `2 * n + d = n + (n + d)`] THEN
796 ONCE_REWRITE_TAC[GSYM SUM_SPLIT] THEN
797 REWRITE_TAC[REAL_ARITH `(a = a + b) <=> (b = &0)`] THEN
798 MATCH_MP_TAC EQ_TRANS THEN EXISTS_TAC `sum(1 + n,n + d) (\k. &0)` THEN
799 CONJ_TAC THENL [ALL_TAC; REWRITE_TAC[SUM_0]] THEN
800 MATCH_MP_TAC SUM_EQ THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
801 REWRITE_TAC[REAL_ENTIRE] THEN DISJ2_TAC THEN REWRITE_TAC[FLOOR_EQ_0] THEN
802 FIRST_ASSUM(ASSUME_TAC o MATCH_MP (ARITH_RULE
803 `1 + n <= r ==> 0 < r`)) THEN
804 ASM_SIMP_TAC[REAL_LE_RDIV_EQ; REAL_LT_LDIV_EQ; REAL_OF_NUM_LT] THEN
805 REWRITE_TAC[REAL_MUL_LZERO; REAL_POS; REAL_MUL_LID; REAL_OF_NUM_LT] THEN
806 UNDISCH_TAC `1 + n <= r` THEN ARITH_TAC;
809 [REWRITE_TAC[GSYM SUM_CMUL; GSYM SUM_SUB] THEN
810 MATCH_MP_TAC SUM_LE THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
811 REWRITE_TAC[REAL_ARITH `m * f - &2 * m * f' = m * (f - &2 * f')`] THEN
812 GEN_REWRITE_TAC RAND_CONV [GSYM REAL_MUL_RID] THEN
813 MATCH_MP_TAC REAL_LE_LMUL THEN REWRITE_TAC[MANGOLDT_POS] THEN
814 MATCH_MP_TAC(REAL_ARITH
815 `&2 * a <= b /\ b <= &2 * a + &1
816 ==> b - &2 * a <= &1`) THEN
817 ASM_SIMP_TAC[FLOOR_DOUBLE_NUM; ARITH_RULE `0 < r <=> 1 <= r`];
820 `sum(1,2 * n + d) (\d. mangoldt d) - sum(1,n) (\d. mangoldt d) =
821 sum(1,2 * n + d) (\d. if d <= n then &0 else mangoldt d)`
823 [REWRITE_TAC[ARITH_RULE `2 * n + d = n + (n + d)`] THEN
824 ONCE_REWRITE_TAC[GSYM SUM_SPLIT] THEN
825 MATCH_MP_TAC(REAL_ARITH
826 `(c = &0) /\ (b = d) ==> ((a + b) - a = c + d)`) THEN
828 [MATCH_MP_TAC EQ_TRANS THEN
829 EXISTS_TAC `sum(1,n) (\k. &0)` THEN CONJ_TAC THENL
830 [ALL_TAC; REWRITE_TAC[SUM_0]] THEN
831 MATCH_MP_TAC SUM_EQ THEN
832 SIMP_TAC[ARITH_RULE `r < n + 1 <=> r <= n`];
834 MATCH_MP_TAC SUM_EQ THEN
835 SIMP_TAC[ARITH_RULE `1 + n <= r ==> ~(r <= n)`];
837 REWRITE_TAC[GSYM SUM_CMUL; GSYM SUM_SUB] THEN MATCH_MP_TAC SUM_LE THEN
838 X_GEN_TAC `r:num` THEN STRIP_TAC THEN REWRITE_TAC[] THEN
839 REWRITE_TAC[REAL_ARITH `m * a - &2 * m * b = m * (a - &2 * b)`] THEN
841 [MATCH_MP_TAC REAL_LE_MUL THEN REWRITE_TAC[MANGOLDT_POS] THEN
842 ASM_SIMP_TAC[REAL_SUB_LE; FLOOR_DOUBLE_NUM; ARITH_RULE `0 < r <=> 1 <= r`];
844 GEN_REWRITE_TAC LAND_CONV [REAL_ARITH `a = a * &1`] THEN
845 MATCH_MP_TAC REAL_LE_LMUL THEN REWRITE_TAC[MANGOLDT_POS] THEN
846 MATCH_MP_TAC(REAL_ARITH `(b = &0) /\ &1 <= a ==> &1 <= a - &2 * b`) THEN
848 [REWRITE_TAC[FLOOR_EQ_0] THEN
849 ASM_SIMP_TAC[REAL_LE_RDIV_EQ; REAL_LT_LDIV_EQ; REAL_OF_NUM_LT;
850 ARITH_RULE `0 < r <=> 1 <= r`] THEN
851 REWRITE_TAC[REAL_MUL_LZERO; REAL_MUL_LID; REAL_POS] THEN
852 ASM_REWRITE_TAC[REAL_OF_NUM_LT] THEN ASM_REWRITE_TAC[GSYM NOT_LE];
854 MATCH_MP_TAC(REAL_ARITH `(a = &1) ==> &1 <= a`) THEN
855 REWRITE_TAC[GSYM FLOOR_UNIQUE; INTEGER_CLOSED] THEN
856 ASM_SIMP_TAC[REAL_LE_RDIV_EQ; REAL_LT_LDIV_EQ; REAL_OF_NUM_LT;
857 ARITH_RULE `0 < r <=> 1 <= r`] THEN
858 REWRITE_TAC[GSYM REAL_OF_NUM_MUL] THEN
859 REWRITE_TAC[REAL_OF_NUM_LE; REAL_OF_NUM_LT; REAL_OF_NUM_MUL;
860 REAL_OF_NUM_ADD] THEN
861 POP_ASSUM_LIST(MP_TAC o end_itlist CONJ) THEN ARITH_TAC);;
863 (* ------------------------------------------------------------------------- *)
864 (* Map the middle term into multiples of log(n). *)
865 (* ------------------------------------------------------------------------- *)
867 let LN_FACT_DIFF_BOUNDS = prove
868 (`!n. abs((ln(&(FACT(n))) - &2 * ln(&(FACT(n DIV 2)))) - &n * ln(&2))
869 <= &4 * ln(if n = 0 then &1 else &n) + &3`,
870 REPEAT GEN_TAC THEN ASM_CASES_TAC `n = 0` THENL
871 [ASM_SIMP_TAC[FACT; MULT_CLAUSES; LN_1; DIV_0; ARITH_EQ] THEN
872 REWRITE_TAC[REAL_MUL_LZERO] THEN CONV_TAC REAL_RAT_REDUCE_CONV;
874 MP_TAC(SPECL [`n:num`; `2`] DIVISION) THEN ASM_REWRITE_TAC[ARITH_EQ] THEN
875 MAP_EVERY ABBREV_TAC [`q = n DIV 2`; `r = n MOD 2`] THEN
876 DISCH_THEN(CONJUNCTS_THEN2 SUBST_ALL_TAC ASSUME_TAC) THEN
877 ASM_CASES_TAC `q = 0` THENL
878 [UNDISCH_TAC `~(q * 2 + r = 0)` THEN
879 ASM_REWRITE_TAC[MULT_CLAUSES; ADD_CLAUSES] THEN
880 ASM_SIMP_TAC[ARITH_RULE `r < 2 ==> ((r = 0) <=> ~(r = 1))`] THEN
881 DISCH_THEN SUBST_ALL_TAC THEN
882 REWRITE_TAC[num_CONV `1`; FACT; MULT_CLAUSES] THEN
883 CONV_TAC NUM_REDUCE_CONV THEN REWRITE_TAC[LN_1] THEN
884 REWRITE_TAC[REAL_MUL_RZERO; REAL_SUB_LZERO; REAL_SUB_RZERO] THEN
885 REWRITE_TAC[REAL_NEG_0; REAL_SUB_LZERO; REAL_ADD_LID; REAL_MUL_LID] THEN
886 REWRITE_TAC[REAL_ABS_NEG] THEN
887 MATCH_MP_TAC(REAL_ARITH `x <= &2 ==> x <= &3`) THEN
888 SUBST1_TAC(REAL_ARITH `&2 = &1 + &1`) THEN
889 MATCH_MP_TAC(REAL_ARITH
890 `&0 <= x /\ x <= &1 ==> abs(x) <= &1 + &1`) THEN
891 ASM_SIMP_TAC[LN_POS; LN_LE; REAL_OF_NUM_LE; ARITH; REAL_LE_ADDL];
893 MATCH_MP_TAC(REAL_ARITH
894 `!a'. abs((a' - b) - c) <= d - abs(a' - a) ==> abs((a - b) - c) <= d`) THEN
895 EXISTS_TAC `ln(&(FACT(q * 2)))` THEN
896 MP_TAC(SPEC `q:num` LN_FACT_BOUNDS) THEN
897 MP_TAC(SPEC `q * 2` LN_FACT_BOUNDS) THEN
898 ASM_REWRITE_TAC[MULT_EQ_0; ARITH_EQ] THEN
899 MATCH_MP_TAC(REAL_ARITH
900 `abs(a - (a2 - &2 * a1)) <= b - &2 * b1 - b2
901 ==> abs(l2 - a2) <= b2
902 ==> abs(l1 - a1) <= b1
903 ==> abs((l2 - &2 * l1) - a) <= b`) THEN
904 REWRITE_TAC[GSYM REAL_OF_NUM_ADD; GSYM REAL_OF_NUM_MUL] THEN
905 ASM_SIMP_TAC[LN_MUL; REAL_OF_NUM_LT; ARITH;
906 ARITH_RULE `0 < q <=> ~(q = 0)`] THEN
907 REWRITE_TAC[REAL_ARITH
908 `(q * &2 + r) * l2 - ((q * &2) * (lq + l2) - q * &2 - &2 * (q * lq - q)) =
910 ONCE_REWRITE_TAC[REAL_ARITH
911 `x <= a - b - c - d <=> x + b <= a - c - d`] THEN
912 MATCH_MP_TAC REAL_LE_TRANS THEN
913 EXISTS_TAC `ln(&2) + ln(&q * &2 + &r)` THEN CONJ_TAC THENL
914 [MATCH_MP_TAC REAL_LE_ADD2 THEN CONJ_TAC THENL
915 [MATCH_MP_TAC(REAL_ARITH `&0 <= x /\ x <= &1 * y ==> abs(x) <= y`) THEN
916 SIMP_TAC[LN_POS_LT; REAL_LT_IMP_LE; REAL_LE_RMUL_EQ;
917 REAL_LE_MUL; REAL_POS; REAL_OF_NUM_LT; ARITH] THEN
918 REWRITE_TAC[REAL_OF_NUM_LE] THEN UNDISCH_TAC `r < 2` THEN ARITH_TAC;
920 FIRST_ASSUM(DISJ_CASES_THEN SUBST1_TAC o MATCH_MP (ARITH_RULE
921 `r < 2 ==> (r = 0) \/ (r = 1)`))
923 [REWRITE_TAC[ADD_CLAUSES; REAL_SUB_REFL; REAL_ADD_RID; REAL_ABS_NUM] THEN
924 MATCH_MP_TAC LN_POS THEN
925 REWRITE_TAC[REAL_OF_NUM_LE; REAL_OF_NUM_MUL] THEN
926 UNDISCH_TAC `~(q = 0)` THEN ARITH_TAC;
928 REWRITE_TAC[GSYM ADD1; FACT] THEN
929 SIMP_TAC[GSYM REAL_OF_NUM_MUL; LN_MUL; REAL_OF_NUM_LT;
931 REWRITE_TAC[REAL_ARITH `abs(b - (a + b)) = abs a`] THEN
932 REWRITE_TAC[ADD1; GSYM REAL_OF_NUM_SUC; GSYM REAL_OF_NUM_ADD;
933 GSYM REAL_OF_NUM_MUL] THEN
934 MATCH_MP_TAC(REAL_ARITH `&0 <= x ==> abs(x) <= x`) THEN
935 MATCH_MP_TAC LN_POS THEN
936 REWRITE_TAC[REAL_OF_NUM_ADD; REAL_OF_NUM_MUL; REAL_OF_NUM_LE] THEN
939 REWRITE_TAC[REAL_ARITH
940 `l2 + lnn <= (&4 * lnn + &3) - a - b
941 <=> a + b + l2 <= &3 * lnn + &3`] THEN
942 MATCH_MP_TAC REAL_LE_TRANS THEN
943 EXISTS_TAC `&3 * ln(&q * &2) + &3` THEN CONJ_TAC THENL
945 SIMP_TAC[REAL_LE_RADD; REAL_LE_LMUL_EQ; REAL_OF_NUM_LT; ARITH] THEN
946 ASM_SIMP_TAC[LN_MONO_LE; REAL_POS; REAL_OF_NUM_LT;
947 ARITH_RULE `0 < q <=> ~(q = 0)`;
948 REAL_ARITH `&0 < q /\ &0 <= r ==> &0 < q * &2 + r`;
949 REAL_ARITH `&0 < q ==> &0 < q * &2`] THEN
950 REWRITE_TAC[REAL_LE_ADDR; REAL_POS]] THEN
951 ASM_SIMP_TAC[LN_MUL; REAL_OF_NUM_LT; ARITH;
952 ARITH_RULE `0 < q <=> ~(q = 0)`] THEN
953 SUBGOAL_THEN `&0 <= ln(&2)` (fun th -> MP_TAC th THEN REAL_ARITH_TAC) THEN
954 MATCH_MP_TAC LN_POS THEN REWRITE_TAC[REAL_OF_NUM_LE; ARITH]);;
956 (* ------------------------------------------------------------------------- *)
957 (* Hence overall bounds in terms of n * log(2) + constant. *)
958 (* ------------------------------------------------------------------------- *)
960 let PSI_BOUNDS_INDUCT = prove
961 (`!n. &n * ln(&2) - (&4 * ln (if n = 0 then &1 else &n) + &3) <= psi(n) /\
962 psi(n) - psi(n DIV 2)
963 <= &n * ln(&2) + (&4 * ln (if n = 0 then &1 else &n) + &3)`,
964 MESON_TAC[PSI_BOUNDS_LN_FACT; LN_FACT_DIFF_BOUNDS; REAL_ARITH
965 `m <= a /\ b <= m /\ abs(m - n) <= k
966 ==> n - k <= a /\ b <= n + k`]);;
968 (* ------------------------------------------------------------------------- *)
969 (* Evaluation of mangoldt(numeral). *)
970 (* ------------------------------------------------------------------------- *)
973 GEN_REWRITE_CONV I [mangoldt] THENC
974 RATOR_CONV(LAND_CONV PRIMEPOW_CONV) THENC
975 GEN_REWRITE_CONV I [COND_CLAUSES] THENC
976 TRY_CONV(funpow 2 RAND_CONV APRIMEDIVISOR_CONV);;
978 (* ------------------------------------------------------------------------- *)
979 (* More efficient version without two primality tests. *)
980 (* ------------------------------------------------------------------------- *)
984 (`mangoldt 0 = ln(&1)`,
985 REWRITE_TAC[mangoldt; primepow; LN_1] THEN
986 COND_CASES_TAC THEN ASM_MESON_TAC[EXP_EQ_0; PRIME_0])
988 (`mangoldt 1 = ln(&1)`,
989 REWRITE_TAC[mangoldt; primepow; LN_1] THEN COND_CASES_TAC THEN
990 ASM_MESON_TAC[EXP_EQ_1; PRIME_1; NUM_REDUCE_CONV `1 <= 0`])
992 (`prime p ==> 1 <= k /\ (q = p EXP k) ==> (mangoldt q = ln(&p))`,
993 SIMP_TAC[mangoldt; APRIMEDIVISOR_PRIMEPOW] THEN
994 COND_CASES_TAC THEN ASM_MESON_TAC[primepow])
996 (`(p * x = r * y + 1) /\ ~(p = 1) /\ ~(r = 1) /\ (q = p * r * d)
997 ==> (mangoldt q = ln(&1))`,
998 REPEAT STRIP_TAC THEN
999 SUBGOAL_THEN `~(primepow q)`
1000 (fun th -> REWRITE_TAC[LN_1; th; mangoldt]) THEN
1001 REWRITE_TAC[primepow] THEN
1002 DISCH_THEN(X_CHOOSE_THEN `P:num` MP_TAC) THEN
1003 DISCH_THEN(X_CHOOSE_THEN `k:num` MP_TAC) THEN
1004 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
1005 DISCH_THEN SUBST_ALL_TAC THEN
1006 MP_TAC(SPEC `r:num` PRIME_FACTOR) THEN
1007 MP_TAC(SPEC `p:num` PRIME_FACTOR) THEN
1008 ASM_REWRITE_TAC[] THEN
1009 DISCH_THEN(X_CHOOSE_THEN `P_p:num` MP_TAC) THEN
1010 REWRITE_TAC[divides] THEN
1011 DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC) THEN
1012 DISCH_THEN(X_CHOOSE_THEN `d_p:num` SUBST_ALL_TAC) THEN
1013 DISCH_THEN(X_CHOOSE_THEN `P_r:num` MP_TAC) THEN
1014 DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC) THEN
1015 DISCH_THEN(X_CHOOSE_THEN `d_r:num` SUBST_ALL_TAC) THEN
1016 SUBGOAL_THEN `P_p divides P /\ P_r divides P` ASSUME_TAC THENL
1017 [CONJ_TAC THEN MATCH_MP_TAC PRIME_DIVEXP THEN EXISTS_TAC `k:num` THEN
1018 ASM_MESON_TAC[divides; MULT_AC]; ALL_TAC] THEN
1019 SUBGOAL_THEN `(P_p = P) /\ (P_r = P:num)` (CONJUNCTS_THEN SUBST_ALL_TAC)
1020 THENL [ASM_MESON_TAC[prime]; ALL_TAC] THEN
1021 ASM_MESON_TAC[DIVIDES_ADD_REVR; divides; MULT_AC; DIVIDES_ONE; prime])
1022 and p_tm = `p:num` and k_tm = `k:num` and q_tm = `q:num`
1023 and r_tm = `r:num` and d_tm = `d:num`
1024 and x_tm = `x:num` and y_tm = `y:num` and mangoldt_tm = `mangoldt` in
1026 let ptm,tm = dest_comb tm0 in
1027 if ptm <> mangoldt_tm then failwith "expected mangoldt(numeral)" else
1028 let q = dest_numeral tm in
1029 if q =/ Int 0 then pth0
1030 else if q =/ Int 1 then pth1 else
1032 [] -> failwith "internal failure in MANGOLDT_CONV"
1033 | [p,k] -> let th1 = INST [mk_numeral q,q_tm;
1035 mk_numeral k,k_tm] pth2 in
1036 let th2 = MP th1 (EQT_ELIM(PRIME_CONV(lhand(concl th1)))) in
1037 MP th2 (EQT_ELIM(NUM_REDUCE_CONV(lhand(concl th2))))
1038 | (p,_)::(r,_)::_ ->
1039 let d = q // (p */ r) in
1040 let (x,y) = bezout(p,r) in
1042 if x </ Int 0 then r,p,y,minus_num x
1043 else p,r,x,minus_num y in
1044 let th1 = INST [mk_numeral q,q_tm;
1049 mk_numeral d,d_tm] pth3 in
1050 MP th1 (EQT_ELIM(NUM_REDUCE_CONV(lhand(concl th1))));;
1052 (* ------------------------------------------------------------------------- *)
1053 (* Hence an evaluation function for psi, applied to all n <= some N. *)
1054 (* ------------------------------------------------------------------------- *)
1059 REWRITE_TAC[psi; sum; LN_1])
1061 (`psi(SUC n) = psi(n) + mangoldt(SUC n)`,
1062 REWRITE_TAC[psi; sum; ADD1] THEN REWRITE_TAC[ADD_AC])
1065 SIMP_CONV [REAL_ADD_RID; GSYM LN_MUL; REAL_OF_NUM_MUL;
1066 REAL_OF_NUM_LT; ARITH] in
1067 let rec PSI_LIST n =
1068 if n = 0 then [PSI_0] else
1069 let ths = PSI_LIST (n - 1) in
1070 let th1 = INST [mk_small_numeral(n-1),n_tm] PSI_SUC in
1071 let th2 = GEN_REWRITE_RULE (RAND_CONV o LAND_CONV) [hd ths] th1 in
1072 let th3 = CONV_RULE(COMB_CONV (funpow 2 RAND_CONV NUM_SUC_CONV)) th2 in
1073 let th4 = CONV_RULE (funpow 2 RAND_CONV MANGOLDT_CONV) th3 in
1074 (CONV_RULE(RAND_CONV SIMPER_CONV) th4)::ths in
1077 (* ------------------------------------------------------------------------- *)
1078 (* Run it up to 300. *)
1079 (* ------------------------------------------------------------------------- *)
1081 let PSI_LIST_300 = PSI_LIST 300;;
1083 (* ------------------------------------------------------------------------- *)
1084 (* Prove a sharpish linear bound on psi(n) for n <= 128. *)
1085 (* ------------------------------------------------------------------------- *)
1087 let PSI_UBOUND_128 = prove
1088 (`!n. n <= 128 ==> psi(n) <= &133 / &128 * &n`,
1090 (`a <= b /\ l <= a /\ rest ==> l <= a /\ l <= b /\ rest`,
1091 MESON_TAC[REAL_LE_TRANS])
1092 and tac = time (CONV_TAC(LAND_CONV LN_N2_CONV THENC REALCALC_REL_CONV)) in
1093 REWRITE_TAC[ARITH_RULE `n <= 128 <=> n < 129`] THEN
1094 CONV_TAC EXPAND_CASES_CONV THEN REWRITE_TAC(PSI_LIST_300) THEN
1095 REWRITE_TAC[LN_1] THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
1097 ((MATCH_MP_TAC lemma THEN
1098 CONV_TAC(LAND_CONV REAL_RAT_REDUCE_CONV) THEN
1099 GEN_REWRITE_TAC I [TAUT `T /\ a <=> a`])
1101 (CONJ_TAC THENL [tac THEN NO_TAC; ALL_TAC])
1104 (* ------------------------------------------------------------------------- *)
1105 (* As a multiple of log(2) is often more useful. *)
1106 (* ------------------------------------------------------------------------- *)
1108 let PSI_UBOUND_128_LOG = prove
1109 (`!n. n <= 128 ==> psi(n) <= (&3 / &2 * ln(&2)) * &n`,
1110 GEN_TAC THEN DISCH_THEN(MP_TAC o MATCH_MP PSI_UBOUND_128) THEN
1111 MATCH_MP_TAC(REAL_ARITH `a <= b ==> x <= a ==> x <= b`) THEN
1112 MATCH_MP_TAC REAL_LE_RMUL THEN REWRITE_TAC[REAL_POS] THEN
1113 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV THENC REALCALC_REL_CONV));;
1115 (* ------------------------------------------------------------------------- *)
1116 (* Useful "overpowering" lemma. *)
1117 (* ------------------------------------------------------------------------- *)
1119 let OVERPOWER_LEMMA = prove
1122 (!x. a <= x ==> ((\x. g(x) - f(x)) diffl (d(x)))(x)) /\
1123 (!x. a <= x ==> &0 <= d(x))
1124 ==> !x. a <= x ==> f(x) <= g(x)`,
1125 REPEAT STRIP_TAC THEN
1126 MP_TAC(SPECL [`\x:real. g(x) - f(x)`; `d:real->real`; `a:real`; `x:real`]
1128 UNDISCH_TAC `a <= x` THEN GEN_REWRITE_TAC LAND_CONV [REAL_LE_LT] THEN
1129 ASM_CASES_TAC `x:real = a` THEN ASM_REWRITE_TAC[] THEN
1130 ASM_SIMP_TAC[] THEN DISCH_TAC THEN ASM_REWRITE_TAC[] THEN
1131 DISCH_THEN(X_CHOOSE_THEN `z:real` MP_TAC) THEN
1132 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
1133 MATCH_MP_TAC(REAL_ARITH
1134 `fa <= ga /\ &0 <= d ==> (gx - fx - (ga - fa) = d) ==> fx <= gx`) THEN
1135 ASM_REWRITE_TAC[] THEN MATCH_MP_TAC REAL_LE_MUL THEN
1136 ASM_SIMP_TAC[REAL_SUB_LE; REAL_LT_IMP_LE]);;
1138 (* ------------------------------------------------------------------------- *)
1139 (* Repeatedly extend range of explicit cases using recurrence. *)
1140 (* ------------------------------------------------------------------------- *)
1142 let DOUBLE_CASES_RULE th =
1143 let bod = snd(dest_forall(concl th)) in
1144 let ant,cons = dest_imp bod in
1145 let m = dest_numeral (rand ant)
1146 and c = rat_of_term (lhand(lhand(rand cons))) in
1147 let x = float_of_num(m +/ Int 1) in
1148 let d = (4.0 *. log x +. 3.0) /. (x *. log 2.0) in
1149 let c' = c // Int 2 +/ Int 1 +/
1150 (floor_num(num_of_float(1024.0 *. d)) +/ Int 2) // Int 1024 in
1151 let c'' = max_num c c' in
1154 subst [mk_numeral(Int 2 */ m),rand ant;
1155 term_of_rat c'',lhand(lhand(rand cons))] bod) in
1157 REPEAT STRIP_TAC THEN
1158 ASM_CASES_TAC (mk_comb(`(<=) (n:num)`,mk_numeral m)) THENL
1159 [FIRST_ASSUM(MP_TAC o MATCH_MP th) THEN
1160 MATCH_MP_TAC(REAL_ARITH `a <= b ==> x <= a ==> x <= b`) THEN
1161 MATCH_MP_TAC REAL_LE_RMUL THEN REWRITE_TAC[REAL_POS] THEN
1162 MATCH_MP_TAC REAL_LE_RMUL THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
1163 MATCH_MP_TAC LN_POS THEN CONV_TAC REAL_RAT_REDUCE_CONV;
1165 MP_TAC(SPEC `n:num` PSI_BOUNDS_INDUCT) THEN
1166 SUBGOAL_THEN `~(n = 0)` (fun th -> REWRITE_TAC[th]) THENL
1167 [FIRST_ASSUM(UNDISCH_TAC o check is_neg o concl) THEN ARITH_TAC;
1169 MATCH_MP_TAC(REAL_ARITH
1170 `pn2 <= ((a - &1) * l2) * n - logtm
1171 ==> u <= v /\ pn - pn2 <= n * l2 + logtm ==> pn <= (a * l2) * n`) THEN
1172 MP_TAC(SPEC `n DIV 2` th) THEN
1174 [ASM_SIMP_TAC[LE_LDIV_EQ; ARITH] THEN
1175 FIRST_ASSUM(UNDISCH_TAC o check ((not) o is_neg) o concl) THEN
1178 MATCH_MP_TAC(REAL_ARITH `a <= b ==> x <= a ==> x <= b`) THEN
1180 MATCH_MP_TAC REAL_LE_TRANS THEN
1181 EXISTS_TAC(mk_comb(rator(lhand w),`&n / &2`))) THEN
1183 [MATCH_MP_TAC REAL_LE_LMUL THEN CONJ_TAC THENL
1184 [MATCH_MP_TAC REAL_LE_MUL THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
1185 MATCH_MP_TAC LN_POS THEN CONV_TAC REAL_RAT_REDUCE_CONV;
1187 SIMP_TAC[REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
1188 REWRITE_TAC[REAL_OF_NUM_MUL; REAL_OF_NUM_LE] THEN
1189 MP_TAC(SPECL [`n:num`; `2`] DIVISION) THEN ARITH_TAC;
1191 GEN_REWRITE_TAC (LAND_CONV o RAND_CONV) [real_div] THEN
1192 MATCH_MP_TAC(REAL_ARITH
1193 `logtm <= ((c - a * b) * l2) * n
1194 ==> (a * l2) * n * b <= (c * l2) * n - logtm`) THEN
1195 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1196 SUBST1_TAC(REAL_ARITH `&n = &1 + (&n - &1)`) THEN
1197 FIRST_X_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE
1198 `~(n <= b) ==> b + 1 <= n`)) THEN
1199 GEN_REWRITE_TAC LAND_CONV [GSYM REAL_OF_NUM_LE] THEN
1200 DISCH_THEN(MP_TAC o MATCH_MP (REAL_ARITH
1201 `a <= n ==> a - &1 <= n - &1`)) THEN
1202 ABBREV_TAC `x = &n - &1` THEN
1203 CONV_TAC(LAND_CONV NUM_REDUCE_CONV THENC REAL_RAT_REDUCE_CONV) THEN
1204 SPEC_TAC(`x:real`,`x:real`) THEN POP_ASSUM_LIST(K ALL_TAC) THEN
1205 MATCH_MP_TAC OVERPOWER_LEMMA THEN
1208 (lhand(rator(rand(body(rand(lhand(rand(body(rand w))))))))) in
1210 GEN_REWRITE_TAC (LAND_CONV o TOP_DEPTH_CONV)
1211 [REAL_MUL_LZERO; REAL_ADD_LID; REAL_ADD_RID;
1212 REAL_MUL_RID; REAL_MUL_LID] THEN
1214 let tm = mk_abs(`x:real`,rand(rator(rand(body(rand(lhand w)))))) in
1215 DISCH_TAC THEN EXISTS_TAC tm) THEN
1217 [CONV_TAC REAL_RAT_REDUCE_CONV THEN REWRITE_TAC[real_sub] THEN
1218 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN
1219 CONV_TAC REALCALC_REL_CONV;
1221 REWRITE_TAC[] THEN CONJ_TAC THENL
1223 DISCH_THEN(fun th -> FIRST_ASSUM MATCH_MP_TAC THEN MP_TAC th) THEN
1226 X_GEN_TAC `x:real` THEN DISCH_TAC THEN REWRITE_TAC[REAL_SUB_LE] THEN
1227 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
1228 FIRST_ASSUM(MATCH_MP_TAC o MATCH_MP (REAL_ARITH
1229 `a <= x ==> inv(&1 + x) <= inv(&1 + a) /\
1230 inv(&1 + a) <= b ==> inv(&1 + x) <= b`)) THEN
1232 [MATCH_MP_TAC REAL_LE_INV2 THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
1233 POP_ASSUM MP_TAC THEN REAL_ARITH_TAC;
1235 SIMP_TAC[REAL_LE_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
1236 GEN_REWRITE_TAC RAND_CONV [REAL_MUL_SYM] THEN
1237 SIMP_TAC[GSYM REAL_LE_LDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
1238 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1239 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN CONV_TAC REALCALC_REL_CONV);;
1241 (* ------------------------------------------------------------------------- *)
1242 (* Bring it to the self-sustaining point. *)
1243 (* ------------------------------------------------------------------------- *)
1245 let PSI_UBOUND_1024_LOG = funpow 3 DOUBLE_CASES_RULE PSI_UBOUND_128_LOG;;
1247 (* ------------------------------------------------------------------------- *)
1248 (* A generic proof of the same kind that we're self-sustaining. *)
1249 (* ------------------------------------------------------------------------- *)
1251 let PSI_BOUNDS_SUSTAINED_INDUCT = prove
1252 (`&4 * ln(&1 + &2 pow j) + &3 <= (d * ln(&2)) * (&1 + &2 pow j) /\
1253 &4 / (&1 + &2 pow j) <= d * ln(&2) /\ &0 <= c /\ c / &2 + d + &1 <= c
1255 (!n. n <= 2 EXP k ==> psi(n) <= (c * ln(&2)) * &n)
1256 ==> !n. n <= 2 EXP (SUC k) ==> psi(n) <= (c * ln(&2)) * &n`,
1257 REPEAT STRIP_TAC THEN ASM_CASES_TAC `n <= 2 EXP k` THEN ASM_SIMP_TAC[] THEN
1258 MP_TAC(SPEC `n:num` PSI_BOUNDS_INDUCT) THEN
1259 SUBGOAL_THEN `~(n = 0)` (fun th -> REWRITE_TAC[th]) THENL
1260 [MATCH_MP_TAC(ARITH_RULE `!a. ~(a = 0) /\ ~(n <= a) ==> ~(n = 0)`) THEN
1261 EXISTS_TAC `2 EXP k` THEN ASM_REWRITE_TAC[EXP_EQ_0; ARITH_EQ];
1263 MATCH_MP_TAC(REAL_ARITH
1264 `pn2 <= ((a - &1) * l2) * n - logtm
1265 ==> u <= v /\ pn - pn2 <= n * l2 + logtm ==> pn <= (a * l2) * n`) THEN
1266 FIRST_X_ASSUM(MP_TAC o SPEC `n DIV 2`) THEN
1268 [ASM_SIMP_TAC[LE_LDIV_EQ; ARITH] THEN
1269 MATCH_MP_TAC(ARITH_RULE `n <= 2 * k ==> n < 2 * (k + 1)`) THEN
1270 ASM_REWRITE_TAC[GSYM(CONJUNCT2 EXP)];
1272 MATCH_MP_TAC(REAL_ARITH `a <= b ==> x <= a ==> x <= b`) THEN
1274 MATCH_MP_TAC REAL_LE_TRANS THEN
1275 EXISTS_TAC(mk_comb(rator(lhand w),`&n / &2`))) THEN
1277 [MATCH_MP_TAC REAL_LE_LMUL THEN CONJ_TAC THENL
1278 [MATCH_MP_TAC REAL_LE_MUL THEN ASM_REWRITE_TAC[] THEN
1279 MATCH_MP_TAC LN_POS THEN CONV_TAC REAL_RAT_REDUCE_CONV;
1281 SIMP_TAC[REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
1282 REWRITE_TAC[REAL_OF_NUM_MUL; REAL_OF_NUM_LE] THEN
1283 MP_TAC(SPECL [`n:num`; `2`] DIVISION) THEN ARITH_TAC;
1285 GEN_REWRITE_TAC (LAND_CONV o RAND_CONV) [real_div] THEN
1286 MATCH_MP_TAC(REAL_ARITH
1287 `logtm <= ((c - a * b) * l2) * n
1288 ==> (a * l2) * n * b <= (c * l2) * n - logtm`) THEN
1289 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `(d * ln (&2)) * &n` THEN
1292 MATCH_MP_TAC REAL_LE_RMUL THEN REWRITE_TAC[REAL_POS] THEN
1293 MATCH_MP_TAC REAL_LE_RMUL THEN SIMP_TAC[LN_POS; REAL_OF_NUM_LE; ARITH] THEN
1294 REWRITE_TAC[GSYM real_div] THEN
1295 ASM_REWRITE_TAC[REAL_ARITH `d <= c - &1 - c2 <=> c2 + d + &1 <= c`]] THEN
1296 SUBST1_TAC(REAL_ARITH `&n = &1 + (&n - &1)`) THEN
1297 SUBGOAL_THEN `&2 pow j <= &n - &1` MP_TAC THENL
1298 [MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&2 pow k` THEN CONJ_TAC THENL
1299 [ASM_SIMP_TAC[REAL_POW_MONO; REAL_OF_NUM_LE; ARITH]; ALL_TAC] THEN
1300 FIRST_X_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE
1301 `~(n <= b) ==> b + 1 <= n`)) THEN
1302 GEN_REWRITE_TAC LAND_CONV [GSYM REAL_OF_NUM_LE] THEN
1303 REWRITE_TAC[GSYM REAL_OF_NUM_ADD; GSYM REAL_OF_NUM_POW] THEN
1306 ABBREV_TAC `x = &n - &1` THEN SPEC_TAC(`x:real`,`x:real`) THEN
1307 MATCH_MP_TAC OVERPOWER_LEMMA THEN
1310 (lhand(rator(rand(body(rand(lhand(rand(body(rand w))))))))) in
1312 GEN_REWRITE_TAC (LAND_CONV o TOP_DEPTH_CONV)
1313 [REAL_MUL_LZERO; REAL_ADD_LID; REAL_ADD_RID;
1314 REAL_MUL_RID; REAL_MUL_LID] THEN
1316 let tm = mk_abs(`x:real`,rand(rator(rand(body(rand(lhand w)))))) in
1317 DISCH_TAC THEN EXISTS_TAC tm) THEN
1319 [FIRST_ASSUM ACCEPT_TAC; ALL_TAC] THEN
1320 REWRITE_TAC[] THEN CONJ_TAC THENL
1322 DISCH_THEN(fun th -> FIRST_ASSUM MATCH_MP_TAC THEN MP_TAC th) THEN
1323 MATCH_MP_TAC(REAL_ARITH `&0 < a ==> a <= x ==> &0 < &1 + x`) THEN
1324 SIMP_TAC[REAL_POW_LT; REAL_OF_NUM_LT; ARITH];
1326 X_GEN_TAC `z:real` THEN DISCH_TAC THEN REWRITE_TAC[REAL_SUB_LE] THEN
1327 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
1328 FIRST_ASSUM(MATCH_MP_TAC o MATCH_MP (REAL_ARITH
1329 `a <= x ==> inv(&1 + x) <= inv(&1 + a) /\
1330 inv(&1 + a) <= b ==> inv(&1 + x) <= b`)) THEN
1332 [MATCH_MP_TAC REAL_LE_INV2 THEN ASM_REWRITE_TAC[REAL_LE_LADD] THEN
1333 ASM_SIMP_TAC[REAL_POW_LT; REAL_OF_NUM_LT; ARITH; REAL_ARITH
1334 `&0 < x ==> &0 < &1 + x`];
1336 SIMP_TAC[REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
1337 GEN_REWRITE_TAC LAND_CONV [REAL_MUL_SYM] THEN
1338 ASM_REWRITE_TAC[GSYM real_div]);;
1340 let PSI_BOUNDS_SUSTAINED = prove
1341 (`(!n. n <= 2 EXP k ==> psi(n) <= (c * ln(&2)) * &n)
1342 ==> &4 * ln(&1 + &2 pow k) + &3
1343 <= ((c / &2 - &1) * ln(&2)) * (&1 + &2 pow k) /\
1344 &4 / (&1 + &2 pow k) <= (c / &2 - &1) * ln(&2) /\ &0 <= c
1345 ==> !n. psi(n) <= (c * ln(&2)) * &n`,
1347 (`c / &2 + (c / &2 - &1) + &1 <= c`,
1348 REWRITE_TAC[REAL_ARITH `c2 + (c2 - &1) + &1 = &2 * c2`] THEN
1349 SIMP_TAC[REAL_DIV_LMUL; REAL_OF_NUM_EQ; ARITH_EQ; REAL_LE_REFL]) in
1350 REPEAT GEN_TAC THEN DISCH_TAC THEN
1351 DISCH_THEN(MP_TAC o C CONJ lemma) THEN
1352 ABBREV_TAC `d = c / &2 - &1` THEN REWRITE_TAC[GSYM CONJ_ASSOC] THEN
1353 DISCH_THEN(ASSUME_TAC o MATCH_MP PSI_BOUNDS_SUSTAINED_INDUCT) THEN
1354 X_GEN_TAC `m:num` THEN
1355 SUBGOAL_THEN `?j. m <= 2 EXP j` MP_TAC THENL
1356 [EXISTS_TAC `m:num` THEN SPEC_TAC(`m:num`,`m:num`) THEN
1357 POP_ASSUM_LIST(K ALL_TAC) THEN INDUCT_TAC THEN REWRITE_TAC[ARITH] THEN
1358 REWRITE_TAC[EXP] THEN MATCH_MP_TAC(ARITH_RULE
1359 `~(a = 0) /\ m <= a ==> SUC m <= 2 * a`) THEN
1360 ASM_REWRITE_TAC[EXP_EQ_0; ARITH_EQ];
1362 REWRITE_TAC[LEFT_IMP_EXISTS_THM] THEN SPEC_TAC(`m:num`,`m:num`) THEN
1363 ONCE_REWRITE_TAC[SWAP_FORALL_THM] THEN INDUCT_TAC THENL
1364 [REPEAT STRIP_TAC THEN FIRST_ASSUM MATCH_MP_TAC THEN
1365 MATCH_MP_TAC LE_TRANS THEN EXISTS_TAC `2 EXP 0` THEN ASM_REWRITE_TAC[] THEN
1366 ASM_REWRITE_TAC[LE_EXP; ARITH_EQ; LE_0];
1368 ASM_CASES_TAC `k <= j:num` THENL [ASM_MESON_TAC[]; ALL_TAC] THEN
1369 SUBGOAL_THEN `2 EXP (SUC j) <= 2 EXP k`
1370 (fun th -> ASM_MESON_TAC[th; LE_TRANS]) THEN
1371 ASM_REWRITE_TAC[LE_EXP; ARITH] THEN
1372 UNDISCH_TAC `~(k <= j:num)` THEN ARITH_TAC);;
1374 (* ------------------------------------------------------------------------- *)
1375 (* Now apply it and get our reasonable bound. *)
1376 (* ------------------------------------------------------------------------- *)
1378 let PSI_UBOUND_LOG = prove
1379 (`!n. psi(n) <= (&4407 / &2048 * ln (&2)) * &n`,
1380 MP_TAC PSI_UBOUND_1024_LOG THEN
1381 SUBST1_TAC(SYM(NUM_REDUCE_CONV `2 EXP 10`)) THEN
1382 DISCH_THEN(MATCH_MP_TAC o MATCH_MP PSI_BOUNDS_SUSTAINED) THEN
1383 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1384 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN
1385 CONJ_TAC THEN CONV_TAC REALCALC_REL_CONV);;
1387 let PSI_UBOUND_3_2 = prove
1388 (`!n. psi(n) <= &3 / &2 * &n`,
1389 GEN_TAC THEN MATCH_MP_TAC REAL_LE_TRANS THEN
1390 EXISTS_TAC `(&4407 / &2048 * ln (&2)) * &n` THEN
1391 REWRITE_TAC[PSI_UBOUND_LOG] THEN
1392 MATCH_MP_TAC REAL_LE_RMUL THEN REWRITE_TAC[REAL_POS] THEN
1393 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN
1394 CONV_TAC REALCALC_REL_CONV);;
1396 (* ------------------------------------------------------------------------- *)
1397 (* Now get a lower bound. *)
1398 (* ------------------------------------------------------------------------- *)
1400 let PSI_LBOUND_3_5 = prove
1401 (`!n. 4 <= n ==> &3 / &5 * &n <= psi(n)`,
1403 (`a <= b /\ b <= l /\ rest ==> a <= l /\ b <= l /\ rest`,
1404 MESON_TAC[REAL_LE_TRANS])
1405 and tac = time (CONV_TAC(RAND_CONV LN_N2_CONV THENC REALCALC_REL_CONV)) in
1406 GEN_TAC THEN ASM_CASES_TAC `n < 300` THENL
1407 [POP_ASSUM MP_TAC THEN SPEC_TAC(`n:num`,`n:num`) THEN
1408 CONV_TAC EXPAND_CASES_CONV THEN
1409 REWRITE_TAC(PSI_LIST_300) THEN
1410 REWRITE_TAC[LN_1; ARITH] THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
1412 ((MATCH_MP_TAC lemma THEN
1413 CONV_TAC(LAND_CONV REAL_RAT_REDUCE_CONV) THEN
1414 GEN_REWRITE_TAC I [TAUT `T /\ a <=> a`])
1416 (CONJ_TAC THENL [tac THEN NO_TAC; ALL_TAC])
1419 DISCH_THEN(K ALL_TAC) THEN
1420 MP_TAC(CONJUNCT1 (SPEC `n:num` PSI_BOUNDS_INDUCT)) THEN
1421 MATCH_MP_TAC(REAL_ARITH `a <= b ==> b <= x ==> a <= x`) THEN
1422 ASM_SIMP_TAC[ARITH_RULE `~(n < 300) ==> ~(n = 0)`] THEN
1423 MATCH_MP_TAC(REAL_ARITH `c <= n * (b - a) ==> a * n <= n * b - c`) THEN
1424 GEN_REWRITE_TAC RAND_CONV [REAL_MUL_SYM] THEN
1425 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&1 / &11 * &n` THEN
1428 MATCH_MP_TAC REAL_LE_RMUL THEN REWRITE_TAC[REAL_POS] THEN
1429 REWRITE_TAC[real_sub] THEN CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN
1430 CONV_TAC REALCALC_REL_CONV] THEN
1431 ABBREV_TAC `x = &n - &1` THEN
1432 SUBGOAL_THEN `&n = &1 + x` SUBST1_TAC THENL
1433 [EXPAND_TAC "x" THEN REAL_ARITH_TAC; ALL_TAC] THEN
1434 SUBGOAL_THEN `&299 <= x` MP_TAC THENL
1435 [EXPAND_TAC "x" THEN REWRITE_TAC[REAL_LE_SUB_LADD] THEN
1436 REWRITE_TAC[REAL_OF_NUM_ADD; REAL_OF_NUM_LE; ARITH] THEN
1437 UNDISCH_TAC `~(n < 300)` THEN ARITH_TAC;
1439 SPEC_TAC(`x:real`,`x:real`) THEN POP_ASSUM_LIST(K ALL_TAC) THEN
1440 MATCH_MP_TAC OVERPOWER_LEMMA THEN
1443 (lhand(rator(rand(body(rand(lhand(rand(body(rand w))))))))) in
1445 GEN_REWRITE_TAC (LAND_CONV o TOP_DEPTH_CONV)
1446 [REAL_MUL_LZERO; REAL_ADD_LID; REAL_ADD_RID;
1447 REAL_MUL_RID; REAL_MUL_LID] THEN
1449 let tm = mk_abs(`x:real`,rand(rator(rand(body(rand(lhand w)))))) in
1450 DISCH_TAC THEN EXISTS_TAC tm) THEN
1452 [CONV_TAC REAL_RAT_REDUCE_CONV THEN
1453 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN
1454 CONV_TAC REALCALC_REL_CONV;
1456 REWRITE_TAC[] THEN CONJ_TAC THENL
1458 DISCH_THEN(fun th -> FIRST_ASSUM MATCH_MP_TAC THEN MP_TAC th) THEN
1461 POP_ASSUM_LIST(K ALL_TAC) THEN GEN_TAC THEN DISCH_TAC THEN
1462 REWRITE_TAC[REAL_SUB_LE] THEN
1463 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
1464 MATCH_MP_TAC REAL_LE_TRANS THEN
1465 EXISTS_TAC `inv(&1 + &299)` THEN CONJ_TAC THENL
1466 [ALL_TAC; CONV_TAC REAL_RAT_REDUCE_CONV] THEN
1467 MATCH_MP_TAC REAL_LE_INV2 THEN
1468 POP_ASSUM MP_TAC THEN REAL_ARITH_TAC);;
1470 (* ========================================================================= *)
1471 (* Now the related theta function. *)
1472 (* ========================================================================= *)
1474 let theta = new_definition
1475 `theta(n) = sum(1,n) (\p. if prime p then ln(&p) else &0)`;;
1477 (* ------------------------------------------------------------------------- *)
1478 (* An optimized rule to give theta(n) for all n <= some N. *)
1479 (* ------------------------------------------------------------------------- *)
1483 (`theta(0) = ln(&1)`,
1484 REWRITE_TAC[theta; sum; LN_1])
1485 and THETA_SUC = prove
1486 (`theta(SUC n) = theta(n) + (if prime(SUC n) then ln(&(SUC n)) else &0)`,
1487 REWRITE_TAC[theta; sum; ADD1] THEN REWRITE_TAC[ADD_AC])
1490 NUM_REDUCE_CONV THENC
1491 ONCE_DEPTH_CONV PRIME_CONV THENC
1492 GEN_REWRITE_CONV TOP_DEPTH_CONV
1493 [COND_CLAUSES; REAL_ADD_LID; REAL_ADD_RID] THENC
1494 SIMP_CONV [GSYM LN_MUL; REAL_OF_NUM_MUL; REAL_OF_NUM_LT; ARITH] in
1495 let rec THETA_LIST n =
1496 if n = 0 then [THETA_0] else
1497 let ths = THETA_LIST (n - 1) in
1498 let th1 = INST [mk_small_numeral(n-1),n_tm] THETA_SUC in
1499 let th2 = GEN_REWRITE_RULE (RAND_CONV o LAND_CONV) [hd ths] th1 in
1500 CONV_RULE SIMPER_CONV th2::ths in
1503 (* ------------------------------------------------------------------------- *)
1504 (* Split up the psi sum to show close relationship with theta. *)
1505 (* ------------------------------------------------------------------------- *)
1507 let PRIMEPOW_ODD_EVEN = prove
1509 ~(prime(p) /\ prime(q) /\ 1 <= j /\ (p EXP (2 * j) = q EXP (2 * k + 1)))`,
1510 REPEAT STRIP_TAC THEN
1511 SUBGOAL_THEN `q divides p` ASSUME_TAC THENL
1512 [MATCH_MP_TAC PRIME_DIVEXP THEN EXISTS_TAC `2 * j` THEN
1513 UNDISCH_TAC `p EXP (2 * j) = q EXP (2 * k + 1)` THEN
1514 REWRITE_TAC[EXP_ADD; EXP_1] THEN
1515 ASM_MESON_TAC[divides; MULT_SYM];
1517 SUBGOAL_THEN `q = p:num` SUBST_ALL_TAC THENL
1518 [ASM_MESON_TAC[prime]; ALL_TAC] THEN
1519 UNDISCH_TAC `p EXP (2 * j) = p EXP (2 * k + 1)` THEN
1520 REWRITE_TAC[GSYM LE_ANTISYM] THEN REWRITE_TAC[LE_EXP] THEN
1521 COND_CASES_TAC THENL [ASM_MESON_TAC[PRIME_0]; ALL_TAC] THEN
1523 SUBGOAL_THEN `~(p = 1)` (fun th -> REWRITE_TAC[th]) THENL
1524 [ASM_MESON_TAC[PRIME_1]; ALL_TAC] THEN
1525 REWRITE_TAC[LE_ANTISYM] THEN
1526 DISCH_THEN(MP_TAC o AP_TERM `EVEN`) THEN
1527 REWRITE_TAC[EVEN_ADD; EVEN_MULT; ARITH_EVEN]);;
1529 let PSI_SPLIT = prove
1530 (`psi(n) = theta(n) +
1531 sum(1,n) (\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k))
1532 then ln(&(aprimedivisor d)) else &0) +
1533 sum(1,n) (\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k + 1))
1534 then ln(&(aprimedivisor d)) else &0)`,
1535 REWRITE_TAC[psi; theta; GSYM SUM_ADD] THEN
1536 MATCH_MP_TAC SUM_EQ THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
1537 REWRITE_TAC[mangoldt; primepow] THEN
1538 ASM_CASES_TAC `?p k. 1 <= k /\ prime p /\ (r = p EXP k)` THEN
1539 ASM_REWRITE_TAC[] THENL
1541 SUBGOAL_THEN `~(?p k. 1 <= k /\ prime p /\ (r = p EXP (2 * k))) /\
1542 ~(?p k. 1 <= k /\ prime p /\ (r = p EXP (2 * k + 1))) /\
1544 (fun th -> REWRITE_TAC[th; REAL_ADD_LID]) THEN
1545 ASM_MESON_TAC[ARITH_RULE `1 <= k ==> 1 <= 2 * k /\ 1 <= 2 * k + 1`;
1546 EXP_1; LE_REFL]] THEN
1547 FIRST_X_ASSUM(X_CHOOSE_THEN `p:num` (X_CHOOSE_THEN `m:num` MP_TAC)) THEN
1548 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
1549 DISCH_THEN SUBST_ALL_TAC THEN
1550 MP_TAC(SPECL [`m:num`; `2`] DIVISION) THEN REWRITE_TAC[ARITH_EQ] THEN
1551 MAP_EVERY ABBREV_TAC [`k = m DIV 2`; `d = m MOD 2`] THEN
1552 DISCH_THEN(CONJUNCTS_THEN2 SUBST_ALL_TAC ASSUME_TAC) THEN
1553 ASM_SIMP_TAC[APRIMEDIVISOR_PRIMEPOW] THEN
1554 FIRST_ASSUM(DISJ_CASES_THEN SUBST_ALL_TAC o MATCH_MP (ARITH_RULE
1555 `d < 2 ==> (d = 0) \/ (d = 1)`)) THEN
1556 ASM_REWRITE_TAC[PRIME_EXP; ADD_EQ_0; MULT_EQ_0; ARITH_EQ] THENL
1557 [UNDISCH_TAC `1 <= k * 2 + 0` THEN REWRITE_TAC[ADD_CLAUSES] THEN
1558 ASM_CASES_TAC `k = 0` THEN ASM_REWRITE_TAC[ARITH] THEN DISCH_TAC THEN
1559 SUBGOAL_THEN `~(k * 2 = 1)` (fun th -> REWRITE_TAC[th]) THENL
1560 [DISCH_THEN(MP_TAC o AP_TERM `EVEN`) THEN
1561 REWRITE_TAC[EVEN_MULT; ARITH_EVEN]; ALL_TAC] THEN
1562 REPEAT(COND_CASES_TAC THEN
1563 ASM_REWRITE_TAC[REAL_ADD_LID; REAL_ADD_RID]) THEN
1564 ASM_MESON_TAC[PRIMEPOW_ODD_EVEN; MULT_SYM;
1565 ARITH_RULE `~(k = 0) ==> 1 <= k`];
1567 ASM_CASES_TAC `k = 0` THENL
1568 [MATCH_MP_TAC(REAL_ARITH
1569 `(a = a') /\ (b = &0) /\ (c = &0) ==> (a = a' + b + c)`) THEN
1571 [ASM_REWRITE_TAC[ARITH; EXP_1]; ALL_TAC] THEN
1572 CONJ_TAC THEN COND_CASES_TAC THEN ASM_REWRITE_TAC[] THENL
1573 [ASM_MESON_TAC[PRIMEPOW_ODD_EVEN; MULT_SYM]; ALL_TAC] THEN
1574 FIRST_X_ASSUM(X_CHOOSE_THEN `q:num` MP_TAC) THEN
1575 DISCH_THEN(X_CHOOSE_THEN `j:num` MP_TAC) THEN STRIP_TAC THEN
1576 SUBGOAL_THEN `q divides p` ASSUME_TAC THENL
1577 [MATCH_MP_TAC PRIME_DIVEXP THEN EXISTS_TAC `k * 2 + 1` THEN
1578 UNDISCH_TAC `p EXP (k * 2 + 1) = q EXP (2 * j + 1)` THEN
1579 REWRITE_TAC[EXP_ADD; EXP_1] THEN
1580 ASM_MESON_TAC[divides; MULT_SYM];
1582 SUBGOAL_THEN `q = p:num` SUBST_ALL_TAC THENL
1583 [ASM_MESON_TAC[prime]; ALL_TAC] THEN
1584 UNDISCH_TAC `p EXP (k * 2 + 1) = p EXP (2 * j + 1)` THEN
1585 REWRITE_TAC[GSYM LE_ANTISYM] THEN REWRITE_TAC[LE_EXP] THEN
1586 ASM_CASES_TAC `p = 0` THENL [ASM_MESON_TAC[PRIME_0]; ALL_TAC] THEN
1587 ASM_REWRITE_TAC[] THEN
1588 ASM_CASES_TAC `p = 1` THENL [ASM_MESON_TAC[PRIME_1]; ALL_TAC] THEN
1589 ASM_REWRITE_TAC[] THEN
1590 REWRITE_TAC[ADD_CLAUSES; MULT_CLAUSES] THEN
1591 REWRITE_TAC[LE_ANTISYM] THEN
1592 ASM_SIMP_TAC[ARITH_RULE `1 <= j ==> ~(1 = 2 * j + 1)`];
1594 ASM_REWRITE_TAC[ARITH_RULE `(k * 2 + 1 = 1) <=> (k = 0)`; ARITH_EQ] THEN
1595 REPEAT(COND_CASES_TAC THEN ASM_REWRITE_TAC[REAL_ADD_LID; REAL_ADD_RID]) THEN
1596 ASM_MESON_TAC[PRIMEPOW_ODD_EVEN; MULT_SYM; ARITH_RULE
1597 `~(k = 0) ==> 1 <= k`]);;
1599 (* ------------------------------------------------------------------------- *)
1600 (* General lemma about sums. *)
1601 (* ------------------------------------------------------------------------- *)
1603 let SUM_SURJECT = prove
1605 (!r. m <= r /\ r < m + n ==> &0 <= f(i r)) /\
1606 (!s. p <= s /\ s < p + q /\ ~(f(s) = &0)
1607 ==> ?r. m <= r /\ r < m + n /\ (i r = s))
1608 ==> sum(p,q) f <= sum(m,n) (\r. f(i r))`,
1609 REPEAT STRIP_TAC THEN MATCH_MP_TAC REAL_LE_TRANS THEN
1610 EXISTS_TAC `sum(m,n) (\r. if p:num <= i(r) /\ i(r) < p + q
1611 then f(i(r)) else &0)` THEN
1614 MATCH_MP_TAC SUM_LE THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
1615 REWRITE_TAC[] THEN COND_CASES_TAC THEN
1616 ASM_MESON_TAC[REAL_LE_REFL; ADD_AC]] THEN
1617 POP_ASSUM_LIST(MP_TAC o end_itlist CONJ) THEN
1618 SPEC_TAC(`q:num`,`q:num`) THEN INDUCT_TAC THENL
1619 [STRIP_TAC THEN REWRITE_TAC[sum] THEN
1620 REWRITE_TAC[ARITH_RULE `~(p <= q /\ q < p + 0)`] THEN
1621 REWRITE_TAC[SUM_0; REAL_LE_REFL];
1623 DISCH_THEN(fun th -> POP_ASSUM MP_TAC THEN STRIP_ASSUME_TAC th) THEN
1625 [ASM_REWRITE_TAC[] THEN
1626 REPEAT STRIP_TAC THEN FIRST_ASSUM MATCH_MP_TAC THEN
1627 ASM_MESON_TAC[ARITH_RULE `s < p + q ==> s < p + SUC q`];
1629 REWRITE_TAC[sum] THEN
1631 `sum(m,n) (\r. if p <= i r /\ i r < p + SUC q then f (i r) else &0) =
1632 sum(m,n) (\r. if p <= i r /\ i r < p + q then f (i r) else &0) +
1633 sum(m,n) (\r. if i r = p + q then f(i r) else &0)`
1635 [REWRITE_TAC[GSYM SUM_ADD] THEN MATCH_MP_TAC SUM_EQ THEN
1636 X_GEN_TAC `r:num` THEN STRIP_TAC THEN REWRITE_TAC[] THEN
1637 ASM_CASES_TAC `(i:num->num) r = p + q` THEN ASM_REWRITE_TAC[] THENL
1638 [REWRITE_TAC[LE_ADD; LT_REFL; ARITH_RULE `p + q < p + SUC q`] THEN
1639 REWRITE_TAC[REAL_ADD_LID; REAL_ADD_RID];
1641 ASM_REWRITE_TAC[ARITH_RULE
1642 `r < p + SUC q <=> (r = p + q) \/ r < p + q`] THEN
1643 REWRITE_TAC[REAL_ADD_RID];
1645 MATCH_MP_TAC(REAL_ARITH `f <= s'' ==> s <= s' ==> s + f <= s' + s''`) THEN
1647 `!s. p <= s /\ s < p + SUC q /\ ~(f s = &0)
1648 ==> (?r:num. m <= r /\ r < m + n /\ (i r = s))` THEN
1649 DISCH_THEN(MP_TAC o SPEC `p + q:num`) THEN
1650 ASM_CASES_TAC `f(p + q:num) = &0` THEN ASM_REWRITE_TAC[] THENL
1651 [MATCH_MP_TAC REAL_LE_TRANS THEN
1652 EXISTS_TAC `sum(m,n) (\r. &0)` THEN CONJ_TAC THENL
1653 [REWRITE_TAC[SUM_0; REAL_LE_REFL]; ALL_TAC] THEN
1654 MATCH_MP_TAC SUM_LE THEN X_GEN_TAC `r:num` THEN
1655 REWRITE_TAC[] THEN COND_CASES_TAC THEN
1656 REWRITE_TAC[REAL_LE_REFL] THEN ASM_MESON_TAC[ADD_SYM];
1658 ANTS_TAC THENL [ARITH_TAC; ALL_TAC] THEN
1659 DISCH_THEN(X_CHOOSE_THEN `s:num` STRIP_ASSUME_TAC) THEN
1660 SUBGOAL_THEN `n = (s - m) + 1 + ((m + n) - (s + 1))` SUBST1_TAC THENL
1661 [MAP_EVERY UNDISCH_TAC [`m <= s:num`; `s < m + n:num`] THEN ARITH_TAC;
1663 REWRITE_TAC[GSYM SUM_SPLIT] THEN
1664 ASM_SIMP_TAC[SUM_1; ARITH_RULE `m <= s ==> (m + (s - m) = s:num)`] THEN
1665 MATCH_MP_TAC(REAL_ARITH `&0 <= x /\ &0 <= y ==> a <= x + a + y`) THEN
1667 [MATCH_MP_TAC REAL_LE_TRANS THEN
1668 EXISTS_TAC `sum(m,s - m) (\r. &0)` THEN CONJ_TAC THENL
1669 [REWRITE_TAC[SUM_0; REAL_LE_REFL]; ALL_TAC] THEN
1670 MATCH_MP_TAC SUM_LE THEN REPEAT STRIP_TAC THEN REWRITE_TAC[] THEN
1671 COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
1672 FIRST_ASSUM(SUBST1_TAC o SYM) THEN FIRST_ASSUM MATCH_MP_TAC THEN
1673 MAP_EVERY UNDISCH_TAC
1674 [`m <= r:num`; `r < s - m + m:num`; `s < m + n:num`; `m <= s:num`] THEN
1676 MATCH_MP_TAC REAL_LE_TRANS THEN
1677 EXISTS_TAC `sum(s + 1,(m + n) - (s + 1)) (\r. &0)` THEN CONJ_TAC THENL
1678 [REWRITE_TAC[SUM_0; REAL_LE_REFL]; ALL_TAC] THEN
1679 MATCH_MP_TAC SUM_LE THEN REPEAT STRIP_TAC THEN REWRITE_TAC[] THEN
1680 COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
1681 FIRST_ASSUM(SUBST1_TAC o SYM) THEN FIRST_ASSUM MATCH_MP_TAC THEN
1682 MAP_EVERY UNDISCH_TAC
1683 [`r < (m + n) - (s + 1) + s + 1:num`;
1684 `s + 1 <= r`; `s < m + n:num`; `m <= s:num`] THEN
1687 (* ------------------------------------------------------------------------- *)
1688 (* Apply this to show that one of the residuals is bounded by the other. *)
1689 (* ------------------------------------------------------------------------- *)
1691 let PSI_RESIDUES_COMPARE_2 = prove
1692 (`sum(2,n) (\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k + 1))
1693 then ln(&(aprimedivisor d)) else &0)
1694 <= sum(2,n) (\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k))
1695 then ln(&(aprimedivisor d)) else &0)`,
1697 [`\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k + 1))
1698 then ln(&(aprimedivisor d)) else &0`;
1699 `\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP k)
1700 then d * (aprimedivisor d) else d`;
1701 `2`; `n:num`; `2`; `n:num`] SUM_SURJECT) THEN
1702 REWRITE_TAC[] THEN ANTS_TAC THENL
1704 [X_GEN_TAC `r:num` THEN STRIP_TAC THEN
1705 ASM_CASES_TAC `?p k. 1 <= k /\ prime p /\ (r = p EXP k)` THEN
1706 ASM_REWRITE_TAC[] THENL
1708 COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
1709 ASM_MESON_TAC[ARITH_RULE `1 <= k ==> 1 <= 2 * k + 1`]] THEN
1710 FIRST_X_ASSUM(X_CHOOSE_THEN `p:num` MP_TAC) THEN
1711 DISCH_THEN(X_CHOOSE_THEN `k:num` MP_TAC) THEN
1712 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
1713 DISCH_THEN SUBST_ALL_TAC THEN
1714 ASM_SIMP_TAC[APRIMEDIVISOR_PRIMEPOW] THEN
1715 COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
1716 SUBGOAL_THEN `p EXP k * p = p EXP (k + 1)` SUBST1_TAC THENL
1717 [REWRITE_TAC[EXP_ADD; EXP_1; MULT_AC]; ALL_TAC] THEN
1718 ASM_SIMP_TAC[APRIMEDIVISOR_PRIMEPOW; ARITH_RULE `1 <= k + 1`] THEN
1719 ASM_MESON_TAC[LN_POS; REAL_OF_NUM_LE; PRIME_GE_2; REAL_LE_REFL;
1720 ARITH_RULE `2 <= n ==> 1 <= n`];
1722 X_GEN_TAC `s:num` THEN
1723 ASM_CASES_TAC `?p k. 1 <= k /\ prime p /\ (s = p EXP (2 * k + 1))` THEN
1724 ASM_REWRITE_TAC[] THEN STRIP_TAC THEN
1725 FIRST_X_ASSUM(X_CHOOSE_THEN `p:num` MP_TAC) THEN
1726 DISCH_THEN(X_CHOOSE_THEN `k:num` MP_TAC) THEN
1727 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
1728 DISCH_THEN SUBST_ALL_TAC THEN
1729 EXISTS_TAC `p EXP (2 * k)` THEN
1730 COND_CASES_TAC THENL
1731 [ALL_TAC; ASM_MESON_TAC[ARITH_RULE `1 <= k ==> 1 <= 2 * k`]] THEN
1732 ASM_SIMP_TAC[APRIMEDIVISOR_PRIMEPOW; EXP_ADD; EXP_1;
1733 ARITH_RULE `1 <= k ==> 1 <= 2 * k`] THEN
1735 [REWRITE_TAC[ARITH_RULE `2 <= n <=> ~(n = 0) /\ ~(n = 1)`;
1736 EXP_EQ_0; EXP_EQ_1] THEN
1737 ASM_MESON_TAC[PRIME_1; PRIME_0;
1738 ARITH_RULE `1 <= k ==> ~(2 * k = 0)`];
1740 MATCH_MP_TAC LET_TRANS THEN EXISTS_TAC `p EXP (2 * k + 1)` THEN
1741 ASM_REWRITE_TAC[LE_EXP] THEN
1742 COND_CASES_TAC THEN UNDISCH_TAC `1 <= k` THEN ARITH_TAC;
1744 MATCH_MP_TAC(REAL_ARITH `b <= c ==> a <= b ==> a <= c`) THEN
1745 MATCH_MP_TAC SUM_LE THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
1747 ASM_CASES_TAC `?p k. 1 <= k /\ prime p /\ (r = p EXP k)` THEN
1748 ASM_REWRITE_TAC[] THENL
1750 REPEAT COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
1751 ASM_MESON_TAC[ARITH_RULE `1 <= k ==> 1 <= 2 * k /\ 1 <= 2 * k + 1`]] THEN
1752 FIRST_X_ASSUM(CHOOSE_THEN (K ALL_TAC)) THEN
1753 ASM_CASES_TAC `?p k. 1 <= k /\ prime p /\ (r = p EXP (2 * k))` THEN
1754 ASM_REWRITE_TAC[] THENL
1755 [FIRST_X_ASSUM(X_CHOOSE_THEN `p:num` MP_TAC) THEN
1756 DISCH_THEN(X_CHOOSE_THEN `k:num` MP_TAC) THEN
1757 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
1758 DISCH_THEN SUBST_ALL_TAC THEN
1759 ASM_SIMP_TAC[APRIMEDIVISOR_PRIMEPOW;
1760 ARITH_RULE `1 <= k ==> 1 <= 2 * k`] THEN
1761 SUBGOAL_THEN `p EXP (2 * k) * p = p EXP (2 * k + 1)` SUBST1_TAC THENL
1762 [REWRITE_TAC[EXP_ADD; EXP_1; MULT_AC]; ALL_TAC] THEN
1763 COND_CASES_TAC THENL [ALL_TAC; ASM_MESON_TAC[]] THEN
1764 ASM_SIMP_TAC[APRIMEDIVISOR_PRIMEPOW; REAL_LE_REFL;
1765 ARITH_RULE `1 <= k ==> 1 <= 2 * k + 1`];
1767 COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
1768 FIRST_X_ASSUM(X_CHOOSE_THEN `p:num` MP_TAC) THEN
1769 DISCH_THEN(X_CHOOSE_THEN `k:num` MP_TAC) THEN
1770 FIRST_ASSUM(UNDISCH_TAC o check is_neg o concl) THEN
1771 MATCH_MP_TAC(TAUT `(b ==> a) ==> ~a ==> b ==> c`) THEN
1772 STRIP_TAC THEN MAP_EVERY EXISTS_TAC [`p:num`; `k:num`] THEN
1773 ASM_REWRITE_TAC[] THEN
1774 MP_TAC(SPEC `r:num` APRIMEDIVISOR) THEN
1775 ASM_SIMP_TAC[ARITH_RULE `2 <= n ==> ~(n = 1)`] THEN
1776 ABBREV_TAC `q = aprimedivisor r` THEN STRIP_TAC THEN
1777 SUBGOAL_THEN `q divides p` ASSUME_TAC THENL
1778 [MATCH_MP_TAC PRIME_DIVEXP THEN EXISTS_TAC `2 * k + 1` THEN
1779 ASM_MESON_TAC[divides; MULT_SYM];
1781 SUBGOAL_THEN `q = p:num` SUBST_ALL_TAC THENL
1782 [ASM_MESON_TAC[prime]; ALL_TAC] THEN
1783 UNDISCH_TAC `r * p = p EXP (2 * k + 1)` THEN
1784 REWRITE_TAC[EXP_ADD; EXP_1; EQ_MULT_RCANCEL] THEN
1785 ASM_MESON_TAC[PRIME_0]);;
1787 let PSI_RESIDUES_COMPARE = prove
1788 (`!n. sum(1,n) (\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k + 1))
1789 then ln(&(aprimedivisor d)) else &0)
1790 <= sum(1,n) (\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k))
1791 then ln(&(aprimedivisor d)) else &0)`,
1793 ASM_CASES_TAC `n = 0` THEN ASM_REWRITE_TAC[sum; REAL_LE_REFL] THEN
1794 FIRST_ASSUM(SUBST1_TAC o MATCH_MP (ARITH_RULE
1795 `~(n = 0) ==> (n = 1 + (n - 1))`)) THEN
1796 REWRITE_TAC[GSYM SUM_SPLIT; SUM_1] THEN
1797 MATCH_MP_TAC(REAL_ARITH
1798 `b <= d /\ (a = &0) /\ (c = &0) ==> a + b <= c + d`) THEN
1799 REWRITE_TAC[PSI_RESIDUES_COMPARE_2; ARITH] THEN
1800 REPEAT(COND_CASES_TAC THEN ASM_REWRITE_TAC[]) THEN
1801 ASM_MESON_TAC[EXP_EQ_1; PRIME_1; ARITH_RULE
1802 `1 <= k ==> ~(2 * k = 0) /\ ~(2 * k + 1 = 0)`]);;
1804 (* ------------------------------------------------------------------------- *)
1805 (* The even residual reduces to the square root case. *)
1806 (* ------------------------------------------------------------------------- *)
1808 let PSI_SQRT = prove
1809 (`!n. psi(ISQRT(n)) =
1810 sum(1,n) (\d. if ?p k. 1 <= k /\ prime p /\ (d = p EXP (2 * k))
1811 then ln(&(aprimedivisor d)) else &0)`,
1812 REWRITE_TAC[psi] THEN INDUCT_TAC THEN
1813 REWRITE_TAC[ISQRT_0; sum; ISQRT_SUC] THEN
1814 ASM_CASES_TAC `?m. SUC n = m EXP 2` THENL
1816 SUBGOAL_THEN `~(?p k. 1 <= k /\ prime p /\ (1 + n = p EXP (2 * k)))`
1818 [ONCE_REWRITE_TAC[MULT_SYM] THEN REWRITE_TAC[EXP_MULT] THEN
1819 ASM_MESON_TAC[ARITH_RULE `1 + n = SUC n`];
1821 ASM_REWRITE_TAC[REAL_ADD_RID]] THEN
1822 ASM_REWRITE_TAC[REAL_EQ_ADD_LCANCEL; sum] THEN
1823 FIRST_X_ASSUM(X_CHOOSE_TAC `m:num`) THEN
1824 SUBGOAL_THEN `1 + ISQRT n = m` SUBST1_TAC THENL
1825 [SUBGOAL_THEN `(1 + ISQRT n) EXP 2 = SUC n` MP_TAC THENL
1827 ASM_REWRITE_TAC[num_CONV `2`; GSYM LE_ANTISYM] THEN
1828 REWRITE_TAC[EXP_MONO_LE_SUC; EXP_MONO_LT_SUC]] THEN
1829 MP_TAC(SPEC `n:num` ISQRT_SUC) THEN
1830 COND_CASES_TAC THENL [ALL_TAC; ASM_MESON_TAC[]] THEN
1831 REWRITE_TAC[ARITH_RULE `1 + n = SUC n`] THEN
1832 DISCH_THEN(SUBST1_TAC o SYM) THEN
1833 MP_TAC(SPEC `SUC n` ISQRT_WORKS) THEN ASM_REWRITE_TAC[] THEN
1834 REWRITE_TAC[num_CONV `2`; GSYM LE_ANTISYM] THEN
1835 REWRITE_TAC[EXP_MONO_LE_SUC; EXP_MONO_LT_SUC] THEN ARITH_TAC;
1837 ASM_REWRITE_TAC[ARITH_RULE `1 + n = SUC n`] THEN
1838 REWRITE_TAC[mangoldt; primepow] THEN
1839 ONCE_REWRITE_TAC[MULT_SYM] THEN REWRITE_TAC[EXP_MULT] THEN
1840 REWRITE_TAC[GSYM LE_ANTISYM; EXP_MONO_LE_SUC; num_CONV `2`] THEN
1841 REWRITE_TAC[LE_ANTISYM] THEN COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
1842 REWRITE_TAC[aprimedivisor] THEN
1843 REPEAT AP_TERM_TAC THEN ABS_TAC THEN
1844 MATCH_MP_TAC(TAUT `(a ==> (b <=> c)) ==> (a /\ b <=> a /\ c)`) THEN
1845 DISCH_TAC THEN REWRITE_TAC[EXP; EXP_1] THEN
1846 ASM_MESON_TAC[DIVIDES_LMUL; PRIME_DIVPROD]);;
1848 (* ------------------------------------------------------------------------- *)
1849 (* Hence the main comparison result. *)
1850 (* ------------------------------------------------------------------------- *)
1852 let PSI_THETA = prove
1853 (`!n. theta(n) + psi(ISQRT n) <= psi(n) /\
1854 psi(n) <= theta(n) + &2 * psi(ISQRT n)`,
1856 GEN_REWRITE_TAC (LAND_CONV o RAND_CONV) [PSI_SPLIT] THEN
1857 GEN_REWRITE_TAC (RAND_CONV o LAND_CONV) [PSI_SPLIT] THEN
1858 MP_TAC(SPEC `n:num` PSI_RESIDUES_COMPARE) THEN
1859 REWRITE_TAC[GSYM PSI_SQRT] THEN
1860 SIMP_TAC[REAL_MUL_2; GSYM REAL_ADD_ASSOC; REAL_LE_LADD; REAL_LE_ADDR] THEN
1861 DISCH_THEN(K ALL_TAC) THEN
1862 MATCH_MP_TAC SUM_POS_GEN THEN X_GEN_TAC `r:num` THEN DISCH_TAC THEN
1863 REWRITE_TAC[] THEN COND_CASES_TAC THEN REWRITE_TAC[REAL_LE_REFL] THEN
1864 FIRST_X_ASSUM(X_CHOOSE_THEN `p:num` MP_TAC) THEN
1865 DISCH_THEN(X_CHOOSE_THEN `k:num` MP_TAC) THEN
1866 REPEAT(DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC)) THEN
1867 DISCH_THEN SUBST1_TAC THEN
1868 ASM_SIMP_TAC[APRIMEDIVISOR_PRIMEPOW;
1869 ARITH_RULE `1 <= k ==> 1 <= 2 * k + 1`] THEN
1870 MATCH_MP_TAC LN_POS THEN REWRITE_TAC[REAL_OF_NUM_LE] THEN
1871 ASM_MESON_TAC[PRIME_0; ARITH_RULE `~(p = 0) ==> 1 <= p`]);;
1873 (* ------------------------------------------------------------------------- *)
1874 (* A trivial one-way comparison is immediate. *)
1875 (* ------------------------------------------------------------------------- *)
1877 let THETA_LE_PSI = prove
1878 (`!n. theta(n) <= psi(n)`,
1879 GEN_TAC THEN REWRITE_TAC[theta; psi] THEN MATCH_MP_TAC SUM_LE THEN
1880 X_GEN_TAC `p:num` THEN STRIP_TAC THEN
1881 ASM_CASES_TAC `prime p` THEN ASM_REWRITE_TAC[MANGOLDT_POS] THEN
1882 ASM_SIMP_TAC[mangoldt; PRIME_PRIMEPOW] THEN
1883 SUBGOAL_THEN `aprimedivisor p = p`
1884 (fun th -> REWRITE_TAC[th; REAL_LE_REFL]) THEN
1885 ASM_MESON_TAC[APRIMEDIVISOR_PRIMEPOW; EXP_1; LE_REFL]);;
1887 (* ------------------------------------------------------------------------- *)
1888 (* A tighter bound on psi on a smaller range, to reduce later case analysis. *)
1889 (* ------------------------------------------------------------------------- *)
1891 let PSI_UBOUND_30 = prove
1892 (`!n. n <= 30 ==> psi(n) <= &65 / &64 * &n`,
1894 (`a <= b /\ l <= a /\ rest ==> l <= a /\ l <= b /\ rest`,
1895 MESON_TAC[REAL_LE_TRANS])
1896 and tac = time (CONV_TAC(LAND_CONV LN_N2_CONV THENC REALCALC_REL_CONV)) in
1897 REWRITE_TAC[ARITH_RULE `n <= 30 <=> n < 31`] THEN
1898 CONV_TAC EXPAND_CASES_CONV THEN REWRITE_TAC(PSI_LIST_300) THEN
1899 REWRITE_TAC[LN_1] THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
1901 ((MATCH_MP_TAC lemma THEN
1902 CONV_TAC(LAND_CONV REAL_RAT_REDUCE_CONV) THEN
1903 GEN_REWRITE_TAC I [TAUT `T /\ a <=> a`])
1905 (CONJ_TAC THENL [tac THEN NO_TAC; ALL_TAC])
1908 (* ------------------------------------------------------------------------- *)
1909 (* Bounds for theta, derived from those for psi. *)
1910 (* ------------------------------------------------------------------------- *)
1912 let THETA_UBOUND_3_2 = prove
1913 (`!n. theta(n) <= &3 / &2 * &n`,
1914 MESON_TAC[REAL_LE_TRANS; PSI_UBOUND_3_2; THETA_LE_PSI]);;
1916 let THETA_LBOUND_1_2 = prove
1917 (`!n. 5 <= n ==> &1 / &2 * &n <= theta(n)`,
1919 (`a <= b /\ b <= l /\ rest ==> a <= l /\ b <= l /\ rest`,
1920 MESON_TAC[REAL_LE_TRANS])
1921 and tac = time (CONV_TAC(RAND_CONV LN_N2_CONV THENC REALCALC_REL_CONV)) in
1922 REPEAT STRIP_TAC THEN ASM_CASES_TAC `n >= 900` THENL
1923 [MP_TAC(CONJUNCT2(SPEC `n:num` PSI_THETA)) THEN
1924 MP_TAC(SPEC `n:num` PSI_LBOUND_3_5) THEN
1925 ASM_SIMP_TAC[ARITH_RULE `n >= 900 ==> 4 <= n`] THEN
1926 MATCH_MP_TAC(REAL_ARITH
1927 `d <= (a - b) * n ==> a * n <= ps ==> ps <= th + d ==> b * n <= th`) THEN
1928 ONCE_REWRITE_TAC[REAL_MUL_SYM] THEN
1929 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
1930 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
1931 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1932 MATCH_MP_TAC REAL_LE_TRANS THEN
1933 EXISTS_TAC `&3 / &2 * &(ISQRT n)` THEN
1934 REWRITE_TAC[PSI_UBOUND_3_2] THEN
1935 GEN_REWRITE_TAC LAND_CONV [REAL_MUL_SYM] THEN
1936 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
1937 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
1938 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1939 SUBGOAL_THEN `&(ISQRT n) pow 2 <= (&n * &1 / &30) pow 2` MP_TAC THENL
1941 ONCE_REWRITE_TAC[GSYM CONTRAPOS_THM] THEN REWRITE_TAC[REAL_NOT_LE] THEN
1942 DISCH_TAC THEN MATCH_MP_TAC REAL_POW_LT2 THEN
1943 ASM_REWRITE_TAC[] THEN CONV_TAC NUM_REDUCE_CONV THEN
1944 MATCH_MP_TAC REAL_LE_MUL THEN REWRITE_TAC[REAL_POS] THEN
1945 CONV_TAC REAL_RAT_REDUCE_CONV] THEN
1946 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&n` THEN CONJ_TAC THENL
1947 [REWRITE_TAC[REAL_OF_NUM_POW; REAL_OF_NUM_LE; ISQRT_WORKS];
1949 REWRITE_TAC[REAL_POW_2; REAL_ARITH
1950 `(a * b) * (a * b) = a * a * b * b`] THEN
1951 GEN_REWRITE_TAC LAND_CONV [GSYM REAL_MUL_RID] THEN
1952 MATCH_MP_TAC REAL_LE_LMUL THEN REWRITE_TAC[REAL_POS] THEN
1953 SIMP_TAC[REAL_MUL_ASSOC; GSYM REAL_LE_LDIV_EQ;
1954 REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
1955 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1956 REWRITE_TAC[REAL_OF_NUM_LE] THEN
1957 UNDISCH_TAC `n >= 900` THEN ARITH_TAC;
1959 ASM_CASES_TAC `n < 413` THENL
1960 [UNDISCH_TAC `5 <= n` THEN UNDISCH_TAC `n < 413` THEN
1961 SPEC_TAC(`n:num`,`n:num`) THEN POP_ASSUM_LIST(K ALL_TAC) THEN
1962 CONV_TAC EXPAND_CASES_CONV THEN CONV_TAC NUM_REDUCE_CONV THEN
1963 REWRITE_TAC(THETA_LIST 412) THEN
1964 REWRITE_TAC[LN_1; ARITH] THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
1966 ((MATCH_MP_TAC lemma THEN
1967 CONV_TAC(LAND_CONV REAL_RAT_REDUCE_CONV) THEN
1968 GEN_REWRITE_TAC I [TAUT `T /\ a <=> a`])
1970 (CONJ_TAC THENL [tac THEN NO_TAC; ALL_TAC])
1973 MP_TAC(CONJUNCT2(SPEC `n:num` PSI_THETA)) THEN
1974 MP_TAC(SPEC `n:num` PSI_LBOUND_3_5) THEN
1975 ASM_SIMP_TAC[ARITH_RULE `5 <= n ==> 4 <= n`] THEN
1976 MATCH_MP_TAC(REAL_ARITH
1977 `d <= (a - b) * n ==> a * n <= ps ==> ps <= th + d ==> b * n <= th`) THEN
1978 ONCE_REWRITE_TAC[REAL_MUL_SYM] THEN
1979 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
1980 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
1981 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1982 MATCH_MP_TAC REAL_LE_TRANS THEN
1983 EXISTS_TAC `&65 / &64 * &(ISQRT n)` THEN CONJ_TAC THENL
1984 [MATCH_MP_TAC PSI_UBOUND_30 THEN
1985 SUBGOAL_THEN `(ISQRT n) EXP (SUC 1) <= 30 EXP (SUC 1)` MP_TAC THENL
1986 [ALL_TAC; REWRITE_TAC[EXP_MONO_LE_SUC]] THEN
1987 MATCH_MP_TAC LE_TRANS THEN EXISTS_TAC `n:num` THEN
1988 REWRITE_TAC[ARITH; ISQRT_WORKS] THEN
1989 UNDISCH_TAC `~(n >= 900)` THEN ARITH_TAC;
1991 GEN_REWRITE_TAC LAND_CONV [REAL_MUL_SYM] THEN
1992 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
1993 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
1994 CONV_TAC REAL_RAT_REDUCE_CONV THEN
1995 SUBGOAL_THEN `&(ISQRT n) pow 2 <= (&n * &16 / &325) pow 2` MP_TAC THENL
1997 ONCE_REWRITE_TAC[GSYM CONTRAPOS_THM] THEN REWRITE_TAC[REAL_NOT_LE] THEN
1998 DISCH_TAC THEN MATCH_MP_TAC REAL_POW_LT2 THEN
1999 ASM_REWRITE_TAC[] THEN CONV_TAC NUM_REDUCE_CONV THEN
2000 MATCH_MP_TAC REAL_LE_MUL THEN REWRITE_TAC[REAL_POS] THEN
2001 CONV_TAC REAL_RAT_REDUCE_CONV] THEN
2002 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&n` THEN CONJ_TAC THENL
2003 [REWRITE_TAC[REAL_OF_NUM_POW; REAL_OF_NUM_LE; ISQRT_WORKS];
2005 REWRITE_TAC[REAL_POW_2; REAL_ARITH
2006 `(a * b) * (a * b) = a * a * b * b`] THEN
2007 GEN_REWRITE_TAC LAND_CONV [GSYM REAL_MUL_RID] THEN
2008 MATCH_MP_TAC REAL_LE_LMUL THEN REWRITE_TAC[REAL_POS] THEN
2009 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2010 SIMP_TAC[GSYM REAL_LE_LDIV_EQ;
2011 REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
2012 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2013 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&413` THEN
2014 CONV_TAC REAL_RAT_REDUCE_CONV THEN REWRITE_TAC[REAL_OF_NUM_LE] THEN
2015 UNDISCH_TAC `~(n < 413)` THEN ARITH_TAC);;
2017 (* ========================================================================= *)
2018 (* Tighten the bounds on weak PNT to get the Bertrand conjecture. *)
2019 (* ========================================================================= *)
2021 let FLOOR_POS = prove
2022 (`!x. &0 <= x ==> &0 <= floor x`,
2023 GEN_TAC THEN STRIP_TAC THEN ASM_CASES_TAC `x < &1` THENL
2024 [ASM_MESON_TAC[FLOOR_EQ_0; REAL_LE_REFL]; ALL_TAC] THEN
2025 MP_TAC(last(CONJUNCTS(SPEC `x:real` FLOOR))) THEN
2026 UNDISCH_TAC `~(x < &1)` THEN REAL_ARITH_TAC);;
2028 let FLOOR_NUM_EXISTS = prove
2029 (`!x. &0 <= x ==> ?k. floor x = &k`,
2030 REPEAT STRIP_TAC THEN MP_TAC(CONJUNCT1(SPEC `x:real` FLOOR)) THEN
2031 REWRITE_TAC[integer] THEN
2032 ASM_MESON_TAC[FLOOR_POS; REAL_ARITH `&0 <= x ==> (abs x = x)`]);;
2034 let FLOOR_DIV_INTERVAL = prove
2036 ==> ((floor(&n / &d) = &k) =
2037 if k = 0 then &n < &d
2038 else &n / &(k + 1) < &d /\ &d <= &n / &k)`,
2039 REPEAT STRIP_TAC THEN ASM_CASES_TAC `k = 0` THENL
2040 [ASM_REWRITE_TAC[FLOOR_EQ_0] THEN
2041 ASM_SIMP_TAC[REAL_LE_RDIV_EQ; REAL_LT_LDIV_EQ; REAL_OF_NUM_LT;
2042 ARITH_RULE `0 < d <=> ~(d = 0)`] THEN
2043 ASM_REWRITE_TAC[REAL_MUL_LZERO; REAL_POS; REAL_MUL_LID; REAL_OF_NUM_LT];
2045 REWRITE_TAC[GSYM FLOOR_UNIQUE; INTEGER_CLOSED] THEN
2046 ASM_SIMP_TAC[REAL_LE_RDIV_EQ; REAL_LT_LDIV_EQ; REAL_OF_NUM_LT;
2047 ARITH_RULE `0 < d <=> ~(d = 0)`; ARITH_RULE `0 < k + 1`] THEN
2048 REWRITE_TAC[REAL_MUL_AC; CONJ_ACI; REAL_OF_NUM_ADD]);;
2050 let FLOOR_DIV_EXISTS = prove
2052 ==> ?k. (floor(&n / &d) = &k) /\
2053 d * k <= n /\ n < d * (k + 1)`,
2054 REPEAT STRIP_TAC THEN
2055 SUBGOAL_THEN `?k. floor (&n / &d) = &k` MP_TAC THENL
2056 [ASM_SIMP_TAC[FLOOR_NUM_EXISTS; REAL_LE_DIV; REAL_POS]; ALL_TAC] THEN
2057 MATCH_MP_TAC MONO_EXISTS THEN
2058 X_GEN_TAC `k:num` THEN SIMP_TAC[] THEN ASM_SIMP_TAC[FLOOR_DIV_INTERVAL] THEN
2060 ASM_REWRITE_TAC[MULT_CLAUSES; LE_0; ADD_CLAUSES; REAL_OF_NUM_LT] THEN
2061 ASM_SIMP_TAC[REAL_LT_LDIV_EQ; REAL_LE_RDIV_EQ; REAL_OF_NUM_LT;
2062 ARITH_RULE `0 < k + 1 /\ (~(k = 0) ==> 0 < k)`] THEN
2063 REWRITE_TAC[REAL_OF_NUM_MUL; REAL_OF_NUM_LT; REAL_OF_NUM_LE] THEN
2064 REWRITE_TAC[CONJ_ACI]);;
2066 let FLOOR_HALF_INTERVAL = prove
2068 ==> (floor (&n / &d) - &2 * floor (&(n DIV 2) / &d) =
2069 if ?k. ODD k /\ n DIV (k + 1) < d /\ d <= n DIV k
2071 let lemma = prove(`ODD(k) ==> ~(k = 0)`,MESON_TAC[EVEN; NOT_EVEN]) in
2072 REPEAT STRIP_TAC THEN
2073 FIRST_ASSUM(MP_TAC o SPEC `n:num` o MATCH_MP FLOOR_DIV_EXISTS) THEN
2074 FIRST_ASSUM(MP_TAC o SPEC `n DIV 2` o MATCH_MP FLOOR_DIV_EXISTS) THEN
2075 DISCH_THEN(X_CHOOSE_THEN `k1:num`
2076 (CONJUNCTS_THEN2 SUBST1_TAC STRIP_ASSUME_TAC)) THEN
2077 DISCH_THEN(X_CHOOSE_THEN `k2:num`
2078 (CONJUNCTS_THEN2 SUBST1_TAC STRIP_ASSUME_TAC)) THEN
2079 MAP_EVERY UNDISCH_TAC [`n DIV 2 < d * (k1 + 1)`; `d * k1 <= n DIV 2`] THEN
2080 ONCE_REWRITE_TAC[TAUT `a /\ b /\ c <=> ~(a ==> ~(b /\ c))`] THEN
2081 SIMP_TAC[GSYM NOT_LE; LE_LDIV_EQ; LE_RDIV_EQ; ARITH_EQ; lemma; ADD_EQ_0] THEN
2082 REWRITE_TAC[NOT_LE; NOT_IMP] THEN DISCH_TAC THEN DISCH_TAC THEN
2083 SUBGOAL_THEN `d * 2 * k1 < d * (k2 + 1) /\ d * k2 < d * 2 * (k1 + 1)`
2084 MP_TAC THENL [ASM_MESON_TAC[LET_TRANS; MULT_AC]; ALL_TAC] THEN
2085 ASM_REWRITE_TAC[LT_MULT_LCANCEL] THEN
2086 DISCH_THEN(MP_TAC o MATCH_MP
2088 `2 * k1 < k2 + 1 /\ k2 < 2 * (k1 + 1)
2089 ==> (k2 = 2 * k1) \/ (k2 = 2 * k1 + 1)`)) THEN
2090 DISCH_THEN(DISJ_CASES_THEN SUBST_ALL_TAC) THEN
2091 REWRITE_TAC[GSYM REAL_OF_NUM_ADD; GSYM REAL_OF_NUM_MUL;
2092 REAL_ADD_SUB; REAL_SUB_REFL] THEN
2093 COND_CASES_TAC THEN ASM_REWRITE_TAC[REAL_OF_NUM_EQ; ARITH_EQ] THENL
2095 FIRST_X_ASSUM(MP_TAC o GEN_REWRITE_RULE I [NOT_EXISTS_THM]) THEN
2096 DISCH_THEN(MP_TAC o SPEC `2 * k1 + 1`) THEN
2097 ASM_REWRITE_TAC[ARITH_ODD; ODD_ADD; ODD_MULT] THEN
2098 ASM_MESON_TAC[MULT_AC]] THEN
2099 FIRST_X_ASSUM(X_CHOOSE_THEN `k:num` MP_TAC) THEN
2100 DISCH_THEN(CONJUNCTS_THEN2 MP_TAC STRIP_ASSUME_TAC) THEN
2101 REWRITE_TAC[ODD_EXISTS; ADD1] THEN
2102 DISCH_THEN(X_CHOOSE_THEN `k3:num` SUBST_ALL_TAC) THEN
2103 SUBGOAL_THEN `d * 2 * k1 < d * ((2 * k3 + 1) + 1) /\
2104 d * (2 * k3 + 1) < d * 2 * (k1 + 1)`
2105 MP_TAC THENL [ASM_MESON_TAC[LET_TRANS; MULT_AC]; ALL_TAC] THEN
2106 ASM_REWRITE_TAC[LT_MULT_LCANCEL] THEN
2107 DISCH_THEN(SUBST_ALL_TAC o MATCH_MP (ARITH_RULE
2108 `2 * k1 < (2 * k3 + 1) + 1 /\ 2 * k3 + 1 < 2 * (k1 + 1)
2109 ==> (k3 = k1)`)) THEN
2110 POP_ASSUM_LIST(MP_TAC o end_itlist CONJ) THEN ARITH_TAC);;
2112 let SUM_EXPAND_LEMMA = prove
2113 (`!n m k. (m + 2 * k = n)
2114 ==> (sum (1,n DIV (2 * k + 1))
2115 (\d. if ?k. ODD k /\ n DIV (k + 1) < d /\ d <= n DIV k
2116 then mangoldt d else &0) =
2117 sum (1,n) (\d. --(&1) pow (d + 1) * psi (n DIV d)) -
2119 (\d. --(&1) pow (d + 1) * psi (n DIV d)))`,
2120 GEN_TAC THEN ASM_CASES_TAC `n = 0` THENL
2121 [ASM_SIMP_TAC[DIV_0; ADD_EQ_0; ARITH_EQ; REAL_SUB_REFL; sum]; ALL_TAC] THEN
2122 MATCH_MP_TAC num_WF THEN X_GEN_TAC `m:num` THEN ASM_CASES_TAC `m = 0` THENL
2123 [DISCH_THEN(K ALL_TAC) THEN ASM_SIMP_TAC[ADD_CLAUSES] THEN
2124 ASM_SIMP_TAC[DIV_REFL; SUM_1; DIV_1; REAL_SUB_REFL] THEN
2125 SUBGOAL_THEN `n DIV (n + 1) = 0` (fun th -> REWRITE_TAC[th; sum]) THEN
2126 ASM_MESON_TAC[DIV_EQ_0; ARITH_RULE `n < n + 1 /\ ~(n + 1 = 0)`];
2128 ASM_CASES_TAC `m = 1` THENL
2129 [DISCH_THEN(K ALL_TAC) THEN ASM_REWRITE_TAC[] THEN
2130 X_GEN_TAC `k:num` THEN DISCH_THEN(SUBST1_TAC o SYM) THEN
2131 REWRITE_TAC[GSYM ADD1; ARITH_RULE `1 + n = SUC n`] THEN
2132 SIMP_TAC[DIV_REFL; NOT_SUC; sum; SUM_1] THEN
2133 REWRITE_TAC[REAL_ADD_SUB; mangoldt] THEN
2134 CONV_TAC(ONCE_DEPTH_CONV PRIMEPOW_CONV) THEN
2135 REWRITE_TAC[COND_ID] THEN CONV_TAC SYM_CONV THEN
2136 REWRITE_TAC[REAL_ENTIRE] THEN DISJ2_TAC THEN
2137 REWRITE_TAC[ARITH_RULE `1 + n = SUC n`] THEN
2138 SIMP_TAC[DIV_REFL; NOT_SUC] THEN REWRITE_TAC(LN_1::PSI_LIST 1);
2140 DISCH_THEN(MP_TAC o SPEC `m - 2`) THEN
2141 ASM_SIMP_TAC[ARITH_RULE `~(m = 0) ==> m - 2 < m`] THEN
2142 DISCH_TAC THEN X_GEN_TAC `k:num` THEN DISCH_TAC THEN
2143 FIRST_X_ASSUM(MP_TAC o SPEC `SUC k`) THEN ANTS_TAC THENL
2144 [POP_ASSUM_LIST(MP_TAC o end_itlist CONJ) THEN ARITH_TAC;
2146 GEN_REWRITE_TAC (LAND_CONV o funpow 2 RAND_CONV o TOP_DEPTH_CONV)
2147 [ARITH_RULE `2 * SUC k = SUC(SUC(2 * k))`; sum] THEN
2148 MATCH_MP_TAC(REAL_ARITH
2149 `(s - ss = x + y) ==> (ss = a - ((b + x) + y)) ==> (s = a - b)`) THEN
2150 REWRITE_TAC[REAL_POW_NEG; EVEN_ADD; ARITH_EVEN; EVEN; EVEN_MULT] THEN
2151 REWRITE_TAC[REAL_POW_ONE; REAL_MUL_LID; REAL_MUL_LNEG] THEN
2152 GEN_REWRITE_TAC (RAND_CONV o ONCE_DEPTH_CONV) [ADD_SYM] THEN
2153 REWRITE_TAC[psi; GSYM real_sub] THEN
2154 MATCH_MP_TAC(REAL_ARITH `!b. (a - b = d) /\ (b = c) ==> (a - c = d)`) THEN
2155 EXISTS_TAC `sum (1,n DIV (SUC (2 * k) + 1))
2156 (\d. if ?k. ODD k /\ n DIV (k + 1) < d /\ d <= n DIV k
2157 then mangoldt d else &0)` THEN
2159 [MATCH_MP_TAC SUM_DIFFERENCES_EQ THEN CONJ_TAC THENL
2160 [MATCH_MP_TAC DIV_MONO2 THEN ARITH_TAC; ALL_TAC] THEN
2161 X_GEN_TAC `r:num` THEN REPEAT STRIP_TAC THEN REWRITE_TAC[] THEN
2162 COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
2163 FIRST_X_ASSUM(MP_TAC o GEN_REWRITE_RULE I [NOT_EXISTS_THM]) THEN
2164 DISCH_THEN(MP_TAC o SPEC `2 * k + 1`) THEN
2165 REWRITE_TAC[ODD_ADD; ODD_MULT; ARITH_ODD] THEN
2166 ASM_REWRITE_TAC[ARITH_RULE `n <= r <=> n < 1 + r`] THEN
2167 ASM_REWRITE_TAC[ARITH_RULE `n < r <=> 1 + n <= r`] THEN
2168 ASM_REWRITE_TAC[ARITH_RULE `(2 * k + 1) + 1 = SUC(2 * k) + 1`];
2170 MATCH_MP_TAC SUM_MORETERMS_EQ THEN CONJ_TAC THENL
2171 [MATCH_MP_TAC DIV_MONO2 THEN ARITH_TAC; ALL_TAC] THEN
2172 X_GEN_TAC `r:num` THEN
2173 REWRITE_TAC[ARITH_RULE `2 * SUC k + 1 = 2 * k + 3`] THEN
2174 REWRITE_TAC[ARITH_RULE `SUC(2 * k) + 1 = 2 * k + 2`] THEN STRIP_TAC THEN
2175 COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
2176 FIRST_X_ASSUM(X_CHOOSE_THEN `oj:num` MP_TAC) THEN
2177 REWRITE_TAC[ODD_EXISTS] THEN
2178 DISCH_THEN(CONJUNCTS_THEN2 ASSUME_TAC MP_TAC) THEN
2179 FIRST_X_ASSUM(X_CHOOSE_THEN `j:num` SUBST1_TAC) THEN
2180 REWRITE_TAC[ARITH_RULE `SUC(2 * k) + 1 = 2 * k + 2`] THEN
2181 REWRITE_TAC[ARITH_RULE `SUC(2 * k) = 2 * k + 1`] THEN
2182 FIRST_X_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE `1 + a <= b ==> a < b`)) THEN
2183 FIRST_X_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE `a < 1 + b ==> a <= b`)) THEN
2184 SIMP_TAC[GSYM NOT_LE; LE_RDIV_EQ; LE_LDIV_EQ; ADD_EQ_0; ARITH_EQ] THEN
2185 REWRITE_TAC[NOT_LE] THEN REPEAT STRIP_TAC THEN
2186 SUBGOAL_THEN `(2 * j + 1) * r < (2 * k + 3) * r /\
2187 (2 * k + 2) * r < (2 * j + 2) * r`
2188 MP_TAC THENL [ASM_MESON_TAC[LET_TRANS]; ALL_TAC] THEN
2189 ASM_REWRITE_TAC[LT_MULT_RCANCEL] THEN
2190 ASM_CASES_TAC `r = 0` THEN ASM_REWRITE_TAC[] THEN
2191 DISCH_THEN(SUBST_ALL_TAC o MATCH_MP (ARITH_RULE
2192 `2 * j + 1 < 2 * k + 3 /\ 2 * k + 2 < 2 * j + 2 ==> (j = k)`)) THEN
2193 ASM_MESON_TAC[LET_TRANS; LT_REFL; MULT_AC]);;
2195 let FACT_EXPAND_PSI = prove
2196 (`!n. ln(&(FACT(n))) - &2 * ln(&(FACT(n DIV 2))) =
2197 sum(1,n) (\d. --(&1) pow (d + 1) * psi(n DIV d))`,
2198 GEN_TAC THEN REWRITE_TAC[MANGOLDT] THEN
2200 `sum (1,n DIV 2) (\d. mangoldt d * floor (&(n DIV 2) / &d)) =
2201 sum (1,n) (\d. mangoldt d * floor (&(n DIV 2) / &d))`
2203 [SUBGOAL_THEN `n = n DIV 2 + (n - n DIV 2)`
2204 (fun th -> GEN_REWRITE_TAC (RAND_CONV o LAND_CONV o RAND_CONV) [th])
2205 THENL [MESON_TAC[SUB_ADD; DIV_LE; ADD_SYM; NUM_REDUCE_CONV `2 = 0`];
2207 REWRITE_TAC[GSYM SUM_SPLIT] THEN
2208 MATCH_MP_TAC(REAL_ARITH `(b = &0) ==> (a = a + b)`) THEN
2209 MATCH_MP_TAC SUM_EQ_0 THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
2210 REWRITE_TAC[REAL_ENTIRE; FLOOR_EQ_0] THEN DISJ2_TAC THEN
2211 SIMP_TAC[REAL_LE_DIV; REAL_POS] THEN
2212 SUBGOAL_THEN `0 < r /\ n DIV 2 < r` MP_TAC THENL
2213 [UNDISCH_TAC `1 + n DIV 2 <= r` THEN ARITH_TAC; ALL_TAC] THEN
2214 SIMP_TAC[REAL_LT_LDIV_EQ; REAL_OF_NUM_LT; REAL_MUL_LID];
2216 REWRITE_TAC[GSYM SUM_CMUL; GSYM SUM_SUB] THEN
2217 REWRITE_TAC[REAL_ARITH `m * x - &2 * m * y = m * (x - &2 * y)`] THEN
2218 MATCH_MP_TAC EQ_TRANS THEN
2220 `sum(1,n) (\d. if ?k. ODD k /\ n DIV (k + 1) < d /\ d <= n DIV k
2221 then mangoldt d else &0)` THEN
2223 [MATCH_MP_TAC SUM_EQ THEN
2224 X_GEN_TAC `r:num` THEN STRIP_TAC THEN REWRITE_TAC[] THEN
2225 ASM_SIMP_TAC[FLOOR_HALF_INTERVAL; ARITH_RULE `1 <= d ==> ~(d = 0)`] THEN
2226 COND_CASES_TAC THEN ASM_REWRITE_TAC[REAL_MUL_RID; REAL_MUL_RZERO];
2228 MP_TAC(SPECL [`n:num`; `n:num`; `0`] SUM_EXPAND_LEMMA) THEN
2229 REWRITE_TAC[ADD_CLAUSES; MULT_CLAUSES; sum; REAL_SUB_RZERO; DIV_1]);;
2231 (* ------------------------------------------------------------------------- *)
2232 (* Show that we can get bounds by cutting off at odd/even points. *)
2233 (* ------------------------------------------------------------------------- *)
2235 let PSI_MONO = prove
2236 (`!m n. m <= n ==> psi(m) <= psi(n)`,
2237 SIMP_TAC[LE_EXISTS; LEFT_IMP_EXISTS_THM; psi] THEN
2238 REWRITE_TAC[GSYM SUM_SPLIT] THEN
2239 REPEAT STRIP_TAC THEN REWRITE_TAC[REAL_LE_ADDR] THEN
2240 MATCH_MP_TAC SUM_POS_GEN THEN REWRITE_TAC[MANGOLDT_POS]);;
2243 (`!n. &0 <= psi(n)`,
2244 SUBGOAL_THEN `psi(0) = &0` (fun th -> MESON_TAC[th; PSI_MONO; LE_0]) THEN
2245 REWRITE_TAC(LN_1::PSI_LIST 0));;
2247 let PSI_EXPANSION_CUTOFF = prove
2249 ==> sum(1,2 * m) (\d. --(&1) pow (d + 1) * psi(n DIV d))
2250 <= sum(1,2 * p) (\d. --(&1) pow (d + 1) * psi(n DIV d)) /\
2251 sum(1,2 * p + 1) (\d. --(&1) pow (d + 1) * psi(n DIV d))
2252 <= sum(1,2 * m + 1) (\d. --(&1) pow (d + 1) * psi(n DIV d))`,
2253 GEN_TAC THEN SIMP_TAC[LE_EXISTS; LEFT_IMP_EXISTS_THM] THEN
2254 GEN_REWRITE_TAC BINDER_CONV [SWAP_FORALL_THM] THEN
2255 SIMP_TAC[LEFT_FORALL_IMP_THM; EXISTS_REFL] THEN
2256 X_GEN_TAC `m:num` THEN INDUCT_TAC THEN
2257 REWRITE_TAC[ADD_CLAUSES; REAL_LE_REFL] THEN
2258 REWRITE_TAC[ARITH_RULE `2 * SUC n = SUC(SUC(2 * n))`;
2259 ARITH_RULE `SUC(SUC n) + 1 = SUC(SUC(n + 1))`; sum] THEN
2260 FIRST_ASSUM(MATCH_MP_TAC o MATCH_MP (REAL_ARITH
2261 `s1 <= s1' /\ s2' <= s2
2262 ==> &0 <= a + b /\ &0 <= --c + --d
2263 ==> s1 <= (s1' + a) + b /\ (s2' + c) + d <= s2`)) THEN
2264 REWRITE_TAC[REAL_POW_NEG; EVEN_ADD; EVEN_MULT; ARITH_EVEN; EVEN] THEN
2265 REWRITE_TAC[REAL_POW_ONE; REAL_MUL_LID; REAL_MUL_LNEG; REAL_NEG_NEG] THEN
2266 REWRITE_TAC[REAL_ARITH `&0 <= a + --b <=> b <= a`] THEN
2267 CONJ_TAC THEN MATCH_MP_TAC PSI_MONO THEN
2268 MATCH_MP_TAC DIV_MONO2 THEN ARITH_TAC);;
2270 let FACT_PSI_BOUND_ODD = prove
2272 ==> ln(&(FACT n)) - &2 * ln(&(FACT (n DIV 2)))
2273 <= sum(1,k) (\d. --(&1) pow (d + 1) * psi(n DIV d))`,
2274 REPEAT STRIP_TAC THEN REWRITE_TAC[FACT_EXPAND_PSI] THEN
2275 ASM_CASES_TAC `k <= n:num` THENL
2277 MATCH_MP_TAC(REAL_ARITH `(b = a) ==> a <= b`) THEN
2278 MATCH_MP_TAC SUM_MORETERMS_EQ THEN
2279 ASM_SIMP_TAC[ARITH_RULE `~(k <= n) ==> n <= k:num`] THEN
2280 X_GEN_TAC `r:num` THEN STRIP_TAC THEN REWRITE_TAC[REAL_ENTIRE] THEN
2281 DISJ2_TAC THEN SUBGOAL_THEN `n DIV r = 0` SUBST1_TAC THENL
2282 [ASM_MESON_TAC[DIV_EQ_0; ARITH_RULE `1 + n <= r ==> n < r /\ ~(r = 0)`];
2283 REWRITE_TAC(LN_1::PSI_LIST 0)]] THEN
2284 FIRST_X_ASSUM(MP_TAC o GEN_REWRITE_RULE I [ODD_EXISTS]) THEN
2285 DISCH_THEN(X_CHOOSE_THEN `m:num` SUBST_ALL_TAC) THEN
2286 MATCH_MP_TAC REAL_LE_TRANS THEN
2287 EXISTS_TAC `sum(1,SUC(2 * n DIV 2))
2288 (\d. -- &1 pow (d + 1) * psi (n DIV d))` THEN
2291 SUBGOAL_THEN `m <= n DIV 2`
2292 (fun th -> SIMP_TAC[th; ADD1; PSI_EXPANSION_CUTOFF]) THEN
2293 SIMP_TAC[LE_RDIV_EQ; ARITH_EQ] THEN
2294 POP_ASSUM MP_TAC THEN ARITH_TAC] THEN
2295 MP_TAC(SPECL [`n:num`; `2`] DIVISION) THEN REWRITE_TAC[ARITH_EQ] THEN
2296 MAP_EVERY ABBREV_TAC [`q = n DIV 2`; `r = n MOD 2`] THEN
2297 DISCH_THEN(CONJUNCTS_THEN2
2298 (fun th -> GEN_REWRITE_TAC (LAND_CONV o LAND_CONV o RAND_CONV) [th])
2300 REWRITE_TAC[ARITH_RULE `r < 2 <=> (r = 0) \/ (r = 1)`] THEN
2301 DISCH_THEN(DISJ_CASES_THEN SUBST_ALL_TAC) THEN
2302 REWRITE_TAC[ADD1; MULT_AC; REAL_LE_REFL] THEN
2303 REWRITE_TAC[GSYM ADD1; ADD_CLAUSES; sum; REAL_LE_ADDR] THEN
2304 REWRITE_TAC[REAL_POW_NEG; EVEN; EVEN_ADD; EVEN_MULT; ARITH_EVEN] THEN
2305 REWRITE_TAC[REAL_POW_ONE; REAL_MUL_LID; PSI_POS]);;
2307 let FACT_PSI_BOUND_EVEN = prove
2309 ==> sum(1,k) (\d. --(&1) pow (d + 1) * psi(n DIV d))
2310 <= ln(&(FACT n)) - &2 * ln(&(FACT (n DIV 2)))`,
2311 REPEAT STRIP_TAC THEN REWRITE_TAC[FACT_EXPAND_PSI] THEN
2312 ASM_CASES_TAC `k <= n:num` THENL
2314 MATCH_MP_TAC(REAL_ARITH `(a = b) ==> a <= b`) THEN
2315 MATCH_MP_TAC SUM_MORETERMS_EQ THEN
2316 ASM_SIMP_TAC[ARITH_RULE `~(k <= n) ==> n <= k:num`] THEN
2317 X_GEN_TAC `r:num` THEN STRIP_TAC THEN REWRITE_TAC[REAL_ENTIRE] THEN
2318 DISJ2_TAC THEN SUBGOAL_THEN `n DIV r = 0` SUBST1_TAC THENL
2319 [ASM_MESON_TAC[DIV_EQ_0; ARITH_RULE `1 + n <= r ==> n < r /\ ~(r = 0)`];
2320 REWRITE_TAC(LN_1::PSI_LIST 0)]] THEN
2321 FIRST_X_ASSUM(MP_TAC o GEN_REWRITE_RULE I [EVEN_EXISTS]) THEN
2322 DISCH_THEN(X_CHOOSE_THEN `m:num` SUBST_ALL_TAC) THEN
2323 MATCH_MP_TAC REAL_LE_TRANS THEN
2324 EXISTS_TAC `sum(1,2 * n DIV 2)
2325 (\d. -- &1 pow (d + 1) * psi (n DIV d))` THEN
2327 [SUBGOAL_THEN `m <= n DIV 2`
2328 (fun th -> SIMP_TAC[th; ADD1; PSI_EXPANSION_CUTOFF]) THEN
2329 SIMP_TAC[LE_RDIV_EQ; ARITH_EQ] THEN
2330 POP_ASSUM MP_TAC THEN ARITH_TAC;
2332 MP_TAC(SPECL [`n:num`; `2`] DIVISION) THEN REWRITE_TAC[ARITH_EQ] THEN
2333 MAP_EVERY ABBREV_TAC [`q = n DIV 2`; `r = n MOD 2`] THEN
2334 DISCH_THEN(CONJUNCTS_THEN2
2335 (fun th -> GEN_REWRITE_TAC (RAND_CONV o LAND_CONV o RAND_CONV) [th])
2337 REWRITE_TAC[ARITH_RULE `r < 2 <=> (r = 0) \/ (r = 1)`] THEN
2338 DISCH_THEN(DISJ_CASES_THEN SUBST_ALL_TAC) THEN
2339 REWRITE_TAC[ADD1; MULT_AC; ADD_CLAUSES; REAL_LE_REFL] THEN
2340 REWRITE_TAC[GSYM ADD1; ADD_CLAUSES; sum; REAL_LE_ADDR] THEN
2341 REWRITE_TAC[REAL_POW_NEG; EVEN; EVEN_ADD; EVEN_MULT; ARITH_EVEN] THEN
2342 REWRITE_TAC[REAL_POW_ONE; REAL_MUL_LID; PSI_POS]);;
2344 (* ------------------------------------------------------------------------- *)
2345 (* In particular, we will use these. *)
2346 (* ------------------------------------------------------------------------- *)
2348 let FACT_PSI_BOUND_2_3 = prove
2349 (`!n. psi(n) - psi(n DIV 2)
2350 <= ln(&(FACT n)) - &2 * ln(&(FACT (n DIV 2))) /\
2351 ln(&(FACT n)) - &2 * ln(&(FACT (n DIV 2)))
2352 <= psi(n) - psi(n DIV 2) + psi(n DIV 3)`,
2354 MP_TAC(SPECL [`n:num`; `2`] FACT_PSI_BOUND_EVEN) THEN
2355 MP_TAC(SPECL [`n:num`; `3`] FACT_PSI_BOUND_ODD) THEN
2356 REWRITE_TAC[ARITH] THEN
2357 CONV_TAC(ONCE_DEPTH_CONV REAL_SUM_CONV) THEN
2358 REWRITE_TAC[ARITH; REAL_ADD_LID; DIV_1] THEN
2359 REWRITE_TAC[REAL_POW_NEG; ARITH; REAL_POW_ONE; REAL_MUL_LID] THEN
2362 (* ------------------------------------------------------------------------- *)
2363 (* Hence get a good lower bound on psi(n) - psi(n/2). *)
2364 (* ------------------------------------------------------------------------- *)
2366 let PSI_DOUBLE_LEMMA = prove
2367 (`!n. n >= 1200 ==> &n / &6 <= psi(n) - psi(n DIV 2)`,
2368 REPEAT STRIP_TAC THEN MP_TAC(SPEC `n:num` FACT_PSI_BOUND_2_3) THEN
2369 MATCH_MP_TAC(REAL_ARITH
2370 `b + p3 <= a ==> u <= v /\ a <= p - p2 + p3 ==> b <= p - p2`) THEN
2371 MATCH_MP_TAC REAL_LE_TRANS THEN
2372 EXISTS_TAC `&n / &6 + &n / &2` THEN CONJ_TAC THENL
2373 [REWRITE_TAC[REAL_LE_LADD] THEN MP_TAC(SPEC `n DIV 3` PSI_UBOUND_3_2) THEN
2374 MATCH_MP_TAC(REAL_ARITH `a <= b ==> x <= a ==> x <= b`) THEN
2375 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&3 / &2 * &n / &3` THEN
2377 [MATCH_MP_TAC REAL_LE_LMUL THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
2378 SIMP_TAC[REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
2379 REWRITE_TAC[REAL_OF_NUM_MUL; REAL_OF_NUM_LE] THEN
2380 MP_TAC(SPECL [`n:num`; `3`] DIVISION) THEN ARITH_TAC;
2381 ONCE_REWRITE_TAC[REAL_MUL_SYM] THEN
2382 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
2383 CONV_TAC REAL_RAT_REDUCE_CONV THEN REWRITE_TAC[REAL_LE_REFL]];
2385 MP_TAC(SPEC `n:num` LN_FACT_DIFF_BOUNDS) THEN
2386 MATCH_MP_TAC(REAL_ARITH
2387 `ltm <= nl2 - a ==> abs(lf - nl2) <= ltm ==> a <= lf`) THEN
2388 ASM_SIMP_TAC[ARITH_RULE `n >= 1200 ==> ~(n = 0)`] THEN
2389 REWRITE_TAC[real_div; GSYM REAL_SUB_LDISTRIB; GSYM REAL_ADD_LDISTRIB] THEN
2390 MATCH_MP_TAC REAL_LE_TRANS THEN
2391 EXISTS_TAC `&n * &1 / &38` THEN CONJ_TAC THENL
2393 MATCH_MP_TAC REAL_LE_LMUL THEN REWRITE_TAC[REAL_POS] THEN
2394 SIMP_TAC[REAL_LE_SUB_LADD] THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
2395 CONV_TAC(RAND_CONV LN_N2_CONV) THEN CONV_TAC REALCALC_REL_CONV] THEN
2396 SUBST1_TAC(REAL_ARITH `&n = &1 + (&n - &1)`) THEN
2397 FIRST_X_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE
2398 `n >= b ==> b <= n:num`)) THEN
2399 GEN_REWRITE_TAC LAND_CONV [GSYM REAL_OF_NUM_LE] THEN
2400 DISCH_THEN(MP_TAC o MATCH_MP (REAL_ARITH
2401 `a <= n ==> a - &1 <= n - &1`)) THEN
2402 ABBREV_TAC `x = &n - &1` THEN
2403 CONV_TAC(LAND_CONV NUM_REDUCE_CONV THENC REAL_RAT_REDUCE_CONV) THEN
2404 SPEC_TAC(`x:real`,`x:real`) THEN POP_ASSUM_LIST(K ALL_TAC) THEN
2405 MATCH_MP_TAC OVERPOWER_LEMMA THEN
2408 (lhand(rator(rand(body(rand(lhand(rand(body(rand w))))))))) in
2410 GEN_REWRITE_TAC (LAND_CONV o TOP_DEPTH_CONV)
2411 [REAL_MUL_LZERO; REAL_ADD_LID; REAL_ADD_RID;
2412 REAL_MUL_RID; REAL_MUL_LID] THEN
2414 let tm = mk_abs(`x:real`,rand(rator(rand(body(rand(lhand w)))))) in
2415 DISCH_TAC THEN EXISTS_TAC tm) THEN
2417 [CONV_TAC REAL_RAT_REDUCE_CONV THEN REWRITE_TAC[real_sub] THEN
2418 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN
2419 CONV_TAC REALCALC_REL_CONV;
2421 REWRITE_TAC[] THEN CONJ_TAC THENL
2423 DISCH_THEN(fun th -> FIRST_ASSUM MATCH_MP_TAC THEN MP_TAC th) THEN
2426 X_GEN_TAC `x:real` THEN DISCH_TAC THEN REWRITE_TAC[REAL_SUB_LE] THEN
2427 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
2428 FIRST_ASSUM(MATCH_MP_TAC o MATCH_MP (REAL_ARITH
2429 `a <= x ==> inv(&1 + x) <= inv(&1 + a) /\
2430 inv(&1 + a) <= b ==> inv(&1 + x) <= b`)) THEN
2432 [MATCH_MP_TAC REAL_LE_INV2 THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
2433 POP_ASSUM MP_TAC THEN REAL_ARITH_TAC;
2435 CONV_TAC REAL_RAT_REDUCE_CONV);;
2437 (* ------------------------------------------------------------------------- *)
2438 (* Hence show that theta changes (could get a lower bound like n/10). *)
2439 (* ------------------------------------------------------------------------- *)
2441 let THETA_DOUBLE_LEMMA = prove
2442 (`!n. n >= 1200 ==> theta(n DIV 2) < theta(n)`,
2443 REPEAT STRIP_TAC THEN
2444 MP_TAC(CONJUNCT2 (SPEC `n:num` PSI_THETA)) THEN
2445 MP_TAC(CONJUNCT1 (SPEC `n DIV 2` PSI_THETA)) THEN
2446 FIRST_ASSUM(MP_TAC o MATCH_MP PSI_DOUBLE_LEMMA) THEN
2447 MP_TAC(SPEC `ISQRT(n DIV 2)` PSI_POS) THEN
2449 `&2 * psi (ISQRT n) < &n / &6`
2450 (fun th -> MP_TAC th THEN REAL_ARITH_TAC) THEN
2451 ONCE_REWRITE_TAC[REAL_MUL_SYM] THEN
2452 SIMP_TAC[GSYM REAL_LT_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
2453 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
2454 MATCH_MP_TAC REAL_LET_TRANS THEN EXISTS_TAC `&3 / &2 * &(ISQRT n)` THEN
2455 REWRITE_TAC[PSI_UBOUND_3_2] THEN
2456 GEN_REWRITE_TAC LAND_CONV [REAL_MUL_SYM] THEN
2457 SIMP_TAC[GSYM REAL_LT_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
2458 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
2459 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2460 REWRITE_TAC[real_div; REAL_MUL_LID] THEN
2461 SIMP_TAC[GSYM real_div; REAL_LT_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
2462 REWRITE_TAC[REAL_OF_NUM_MUL; REAL_OF_NUM_LT] THEN
2463 SUBGOAL_THEN `(ISQRT n * 18) EXP (SUC 1) < n EXP (SUC 1)` MP_TAC THENL
2464 [ALL_TAC; REWRITE_TAC[EXP_MONO_LT_SUC]] THEN
2465 REWRITE_TAC[EXP; EXP_1] THEN
2466 MATCH_MP_TAC(ARITH_RULE `324 * i * i < a ==> (i * 18) * (i * 18) < a`) THEN
2467 MATCH_MP_TAC LET_TRANS THEN EXISTS_TAC `324 * n` THEN CONJ_TAC THENL
2468 [REWRITE_TAC[GSYM EXP_2; ISQRT_WORKS; LE_MULT_LCANCEL];
2469 REWRITE_TAC[LT_MULT_RCANCEL] THEN POP_ASSUM MP_TAC THEN ARITH_TAC]);;
2471 (* ------------------------------------------------------------------------- *)
2472 (* Hence Bertrand for sufficiently large n. *)
2473 (* ------------------------------------------------------------------------- *)
2475 let BIG_BERTRAND = prove
2476 (`!n. n >= 2400 ==> ?p. prime(p) /\ n <= p /\ p <= 2 * n`,
2477 REPEAT STRIP_TAC THEN MP_TAC(SPEC `2 * n` THETA_DOUBLE_LEMMA) THEN
2478 ANTS_TAC THENL [POP_ASSUM MP_TAC THEN ARITH_TAC; ALL_TAC] THEN
2479 SIMP_TAC[DIV_MULT; ARITH_EQ] THEN
2480 ONCE_REWRITE_TAC[GSYM CONTRAPOS_THM] THEN
2481 REWRITE_TAC[NOT_EXISTS_THM; TAUT `~(a /\ b /\ c) <=> b /\ c ==> ~a`] THEN
2483 SUBGOAL_THEN `sum(n + 1,n) (\p. if prime p then ln (&p) else &0) = &0`
2485 [MATCH_MP_TAC EQ_TRANS THEN EXISTS_TAC `sum(n + 1,n) (\r. &0)` THEN
2486 CONJ_TAC THENL [ALL_TAC; REWRITE_TAC[SUM_0]] THEN
2487 MATCH_MP_TAC SUM_EQ THEN
2488 ASM_SIMP_TAC[ARITH_RULE
2489 `n + 1 <= r /\ r < n + n + 1 ==> n <= r /\ r <= 2 * n`];
2491 MATCH_MP_TAC(REAL_ARITH `(b + a = c) ==> (a = &0) ==> ~(b < c)`) THEN
2492 REWRITE_TAC[theta] THEN ONCE_REWRITE_TAC[ADD_SYM] THEN
2493 REWRITE_TAC[SUM_SPLIT] THEN
2494 REWRITE_TAC[MULT_2]);;
2496 (* ------------------------------------------------------------------------- *)
2497 (* Landau trick. Should be automatic but ARITH_RULE is a bit slow. *)
2498 (* (Direct use of ARITH_RULE takes about 3 minutes on my current laptop.) *)
2499 (* ------------------------------------------------------------------------- *)
2501 let LANDAU_TRICK = prove
2502 (`!n. 0 < n /\ n < 2400
2503 ==> n <= 2 /\ 2 <= 2 * n \/
2504 n <= 3 /\ 3 <= 2 * n \/
2505 n <= 5 /\ 5 <= 2 * n \/
2506 n <= 7 /\ 7 <= 2 * n \/
2507 n <= 13 /\ 13 <= 2 * n \/
2508 n <= 23 /\ 23 <= 2 * n \/
2509 n <= 43 /\ 43 <= 2 * n \/
2510 n <= 83 /\ 83 <= 2 * n \/
2511 n <= 163 /\ 163 <= 2 * n \/
2512 n <= 317 /\ 317 <= 2 * n \/
2513 n <= 631 /\ 631 <= 2 * n \/
2514 n <= 1259 /\ 1259 <= 2 * n \/
2515 n <= 2503 /\ 2503 <= 2 * n`,
2517 `(p /\ b1 ==> a1) /\ (~b1 ==> a2) ==> p ==> b1 /\ a1 \/ a2` in
2518 GEN_TAC THEN ONCE_REWRITE_TAC[TAUT `a /\ b ==> c <=> a ==> c \/ ~b`] THEN
2519 REWRITE_TAC[GSYM DISJ_ASSOC] THEN
2520 REPEAT(MATCH_MP_TAC lemma THEN CONJ_TAC THENL [ARITH_TAC; ALL_TAC]) THEN
2523 (* ------------------------------------------------------------------------- *)
2524 (* Bertrand for all nonzero n using "Landau trick". *)
2525 (* ------------------------------------------------------------------------- *)
2527 let BERTRAND = prove
2528 (`!n. ~(n = 0) ==> ?p. prime p /\ n <= p /\ p <= 2 * n`,
2529 REPEAT STRIP_TAC THEN
2530 DISJ_CASES_TAC(ARITH_RULE `n >= 2400 \/ n < 2400`) THEN
2531 ASM_SIMP_TAC[BIG_BERTRAND] THEN MP_TAC(SPEC `n:num` LANDAU_TRICK) THEN
2532 ASM_REWRITE_TAC[ARITH_RULE `0 < n <=> ~(n = 0)`] THEN
2534 ASM_MESON_TAC(map (PRIME_CONV o curry mk_comb `prime` o mk_small_numeral)
2535 [2;3;5;7;13;23;43;83;163;317;631;1259;2503]));;
2537 (* ========================================================================= *)
2538 (* Weak form of the Prime Number Theorem. *)
2539 (* ========================================================================= *)
2541 let pii = new_definition
2542 `pii(n) = sum(1,n) (\p. if prime(p) then &1 else &0)`;;
2544 (* ------------------------------------------------------------------------- *)
2545 (* An optimized rule to give pii(n) for all n <= some N. *)
2546 (* ------------------------------------------------------------------------- *)
2551 REWRITE_TAC[pii; sum])
2553 (`pii(SUC n) = pii(n) + (if prime(SUC n) then &1 else &0)`,
2554 REWRITE_TAC[pii; sum; ADD1] THEN REWRITE_TAC[ADD_AC])
2557 NUM_REDUCE_CONV THENC
2558 ONCE_DEPTH_CONV PRIME_CONV THENC
2559 GEN_REWRITE_CONV TOP_DEPTH_CONV [COND_CLAUSES] THENC
2560 REAL_RAT_REDUCE_CONV in
2561 let rec PII_LIST n =
2562 if n = 0 then [PII_0] else
2563 let ths = PII_LIST (n - 1) in
2564 let th1 = INST [mk_small_numeral(n-1),n_tm] PII_SUC in
2565 let th2 = GEN_REWRITE_RULE (RAND_CONV o LAND_CONV) [hd ths] th1 in
2566 CONV_RULE SIMPER_CONV th2::ths in
2569 (* ------------------------------------------------------------------------- *)
2570 (* Prove the usual characterization. *)
2571 (* ------------------------------------------------------------------------- *)
2573 let PRIMES_FINITE = prove
2574 (`!n. FINITE {p | p <= n /\ prime(p)}`,
2575 GEN_TAC THEN MATCH_MP_TAC FINITE_SUBSET THEN
2576 EXISTS_TAC `{p | p < SUC n}` THEN REWRITE_TAC[FINITE_NUMSEG_LT] THEN
2577 REWRITE_TAC[SUBSET; IN_ELIM_THM] THEN ARITH_TAC);;
2580 (`!n. pii(n) = &(CARD {p | p <= n /\ prime(p)})`,
2582 [SUBGOAL_THEN `{p | p <= 0 /\ prime p} = {}`
2583 (fun th -> REWRITE_TAC(th::CARD_CLAUSES::PII_LIST 0)) THEN
2584 REWRITE_TAC[EXTENSION; IN_ELIM_THM] THEN
2585 MESON_TAC[LE; PRIME_0; NOT_IN_EMPTY];
2587 SUBGOAL_THEN `{p | p <= SUC n /\ prime p} =
2588 if prime(SUC n) then (SUC n) INSERT {p | p <= n /\ prime p}
2589 else {p | p <= n /\ prime p}`
2591 [COND_CASES_TAC THEN ASM_REWRITE_TAC[EXTENSION; IN_INSERT; IN_ELIM_THM] THEN
2594 REWRITE_TAC[pii; sum] THEN REWRITE_TAC[GSYM pii] THEN
2595 REWRITE_TAC[ARITH_RULE `1 + n = SUC n`] THEN
2596 COND_CASES_TAC THEN ASM_REWRITE_TAC[REAL_ADD_RID] THEN
2597 SIMP_TAC[CARD_CLAUSES; PRIMES_FINITE] THEN COND_CASES_TAC THENL
2598 [RULE_ASSUM_TAC(REWRITE_RULE[IN_ELIM_THM]) THEN
2599 ASM_MESON_TAC[ARITH_RULE `~(SUC n <= n)`];
2600 REWRITE_TAC[REAL_OF_NUM_SUC]]);;
2602 (* ------------------------------------------------------------------------- *)
2603 (* One bound is a simple consequence of the one for theta. *)
2604 (* ------------------------------------------------------------------------- *)
2606 let PII_LBOUND = prove
2607 (`!n. 3 <= n ==> &1 / &2 * (&n / ln(&n)) <= pii(n)`,
2608 REPEAT STRIP_TAC THEN REWRITE_TAC[real_div; REAL_MUL_ASSOC] THEN
2609 ASM_SIMP_TAC[GSYM real_div; REAL_LE_LDIV_EQ; LN_POS_LT; REAL_OF_NUM_LT;
2610 ARITH_RULE `3 <= n ==> 1 < n`] THEN
2611 GEN_REWRITE_TAC RAND_CONV [REAL_MUL_SYM] THEN
2612 FIRST_X_ASSUM(REPEAT_TCL DISJ_CASES_THEN ASSUME_TAC o MATCH_MP
2613 (ARITH_RULE `3 <= n ==> (n = 3) \/ (n = 4) \/ 5 <= n`)) THEN
2614 ASM_REWRITE_TAC(PII_LIST 4) THENL
2615 [CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN CONV_TAC REALCALC_REL_CONV;
2616 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN CONV_TAC REALCALC_REL_CONV;
2618 FIRST_ASSUM(MP_TAC o MATCH_MP THETA_LBOUND_1_2) THEN
2619 MATCH_MP_TAC(REAL_ARITH `x <= y ==> a <= x ==> a <= y`) THEN
2620 REWRITE_TAC[theta; pii; GSYM SUM_CMUL] THEN
2621 MATCH_MP_TAC SUM_LE THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
2622 REWRITE_TAC[] THEN COND_CASES_TAC THEN
2623 REWRITE_TAC[REAL_MUL_RZERO; REAL_MUL_RID; REAL_LE_REFL] THEN
2624 SUBGOAL_THEN `&0 < &r /\ &r <= &n`
2625 (fun th -> MESON_TAC[th; LN_MONO_LE; REAL_LTE_TRANS]) THEN
2626 REWRITE_TAC[REAL_OF_NUM_LT; REAL_OF_NUM_LE] THEN
2627 UNDISCH_TAC `1 <= r` THEN UNDISCH_TAC `r < n + 1` THEN ARITH_TAC);;
2629 (* ------------------------------------------------------------------------- *)
2630 (* First prove the upper bound for the first 50 numbers, to start with. *)
2631 (* ------------------------------------------------------------------------- *)
2633 let PII_UBOUND_CASES_50 = prove
2634 (`!n. n < 50 ==> 3 <= n ==> ln(&n) * pii(n) <= &5 * &n`,
2635 let tac = CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV THENC REALCALC_REL_CONV) in
2636 CONV_TAC EXPAND_CASES_CONV THEN CONV_TAC NUM_REDUCE_CONV THEN
2637 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2638 REWRITE_TAC(PII_LIST 49) THEN
2639 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
2640 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2641 REPEAT(CONJ_TAC THENL [tac THEN NO_TAC; ALL_TAC]) THEN tac);;
2643 (* ------------------------------------------------------------------------- *)
2644 (* An extra trivial pair of lemmas. *)
2645 (* ------------------------------------------------------------------------- *)
2647 let THETA_POS = prove
2648 (`!n. &0 <= theta n`,
2649 GEN_TAC THEN REWRITE_TAC[theta] THEN
2650 MATCH_MP_TAC SUM_POS_GEN THEN
2651 X_GEN_TAC `p:num` THEN DISCH_TAC THEN REWRITE_TAC[] THEN
2653 ASM_SIMP_TAC[LE_REFL; LN_POS; REAL_OF_NUM_LE]);;
2655 let PII_MONO = prove
2656 (`!m n. m <= n ==> pii(m) <= pii(n)`,
2657 SIMP_TAC[LE_EXISTS; LEFT_IMP_EXISTS_THM; pii] THEN
2658 REWRITE_TAC[GSYM SUM_SPLIT] THEN
2659 REPEAT STRIP_TAC THEN REWRITE_TAC[REAL_LE_ADDR] THEN
2660 MATCH_MP_TAC SUM_POS_GEN THEN
2661 GEN_TAC THEN REWRITE_TAC[] THEN COND_CASES_TAC THEN
2662 CONV_TAC REAL_RAT_REDUCE_CONV);;
2665 (`!n. &0 <= pii(n)`,
2666 SUBGOAL_THEN `pii(0) = &0` (fun th -> MESON_TAC[th; PII_MONO; LE_0]) THEN
2667 REWRITE_TAC(LN_1::PII_LIST 0));;
2669 (* ------------------------------------------------------------------------- *)
2670 (* The induction principle we can use. *)
2671 (* ------------------------------------------------------------------------- *)
2673 let PII_CHANGE = prove
2674 (`!m n. ~(m = 0) ==> ln(&m) * (pii n - pii m) <= &3 / &2 * &n`,
2675 REPEAT STRIP_TAC THEN ASM_CASES_TAC `m <= n:num` THENL
2677 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&0` THEN CONJ_TAC THENL
2679 MATCH_MP_TAC REAL_LE_MUL THEN REWRITE_TAC[REAL_POS] THEN
2680 CONV_TAC REAL_RAT_REDUCE_CONV] THEN
2681 MATCH_MP_TAC(REAL_ARITH `&0 <= a * (c - b) ==> a * (b - c) <= &0`) THEN
2682 MATCH_MP_TAC REAL_LE_MUL THEN
2683 ASM_SIMP_TAC[LN_POS; REAL_OF_NUM_LE; ARITH_RULE `1 <= n <=> ~(n = 0)`] THEN
2684 REWRITE_TAC[REAL_SUB_LE] THEN MATCH_MP_TAC PII_MONO THEN
2685 UNDISCH_TAC `~(m <= n:num)` THEN ARITH_TAC] THEN
2686 MATCH_MP_TAC REAL_LE_TRANS THEN
2687 EXISTS_TAC `theta n` THEN REWRITE_TAC[THETA_UBOUND_3_2] THEN
2688 MP_TAC(SPEC `m:num` THETA_POS) THEN
2689 MATCH_MP_TAC(REAL_ARITH `a <= n - m ==> &0 <= m ==> a <= n`) THEN
2690 FIRST_X_ASSUM(MP_TAC o GEN_REWRITE_RULE I [LE_EXISTS]) THEN
2691 DISCH_THEN(X_CHOOSE_THEN `d:num` SUBST1_TAC) THEN
2692 REWRITE_TAC[pii; theta; GSYM SUM_SPLIT; REAL_ADD_SUB] THEN
2693 REWRITE_TAC[GSYM SUM_CMUL] THEN
2694 MATCH_MP_TAC SUM_LE THEN X_GEN_TAC `r:num` THEN STRIP_TAC THEN
2695 REWRITE_TAC[] THEN COND_CASES_TAC THEN
2696 REWRITE_TAC[REAL_MUL_RZERO; REAL_LE_REFL; REAL_MUL_RID] THEN
2697 SUBGOAL_THEN `&0 < &m /\ &m <= &r`
2698 (fun th -> MESON_TAC[th; LN_MONO_LE; REAL_LTE_TRANS]) THEN
2699 REWRITE_TAC[REAL_OF_NUM_LT; REAL_OF_NUM_LE] THEN
2700 UNDISCH_TAC `1 + m <= r` THEN UNDISCH_TAC `~(m = 0)` THEN ARITH_TAC);;
2702 let PII_ISQRT_INDUCT = prove
2705 <= &9 / &4 * (&3 / &2 * &n + ln(&(ISQRT(n))) * pii(ISQRT(n)))`,
2706 REPEAT STRIP_TAC THEN
2707 GEN_REWRITE_TAC RAND_CONV [REAL_MUL_SYM] THEN
2708 SIMP_TAC[GSYM REAL_LE_LDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
2709 GEN_REWRITE_TAC LAND_CONV [real_div] THEN
2710 GEN_REWRITE_TAC LAND_CONV [REAL_MUL_SYM] THEN
2711 REWRITE_TAC[REAL_MUL_ASSOC] THEN
2712 MP_TAC(SPECL [`ISQRT n`; `n:num`] PII_CHANGE) THEN
2713 SUBGOAL_THEN `~(ISQRT n = 0)` ASSUME_TAC THENL
2714 [MP_TAC(SPEC `n:num` ISQRT_WORKS) THEN
2715 ONCE_REWRITE_TAC[GSYM CONTRAPOS_THM] THEN SIMP_TAC[ARITH] THEN
2716 DISCH_TAC THEN UNDISCH_TAC `50 <= n` THEN ARITH_TAC;
2718 ASM_REWRITE_TAC[] THEN MATCH_MP_TAC(REAL_ARITH
2719 `a * p <= ls * p ==> ls * (p - ps) <= an ==> a * p <= an + ls * ps`) THEN
2720 MATCH_MP_TAC REAL_LE_RMUL THEN REWRITE_TAC[PII_POS] THEN
2721 CONV_TAC REAL_RAT_REDUCE_CONV THEN ONCE_REWRITE_TAC[REAL_MUL_SYM] THEN
2722 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
2723 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `ln((&(ISQRT n) + &1) pow 2)` THEN
2725 [SUBGOAL_THEN `&0 < &n /\ &n <= (&(ISQRT n) + &1) pow 2`
2726 (fun th -> MESON_TAC[th; REAL_LTE_TRANS; LN_MONO_LE]) THEN
2727 REWRITE_TAC[REAL_OF_NUM_ADD; REAL_OF_NUM_POW; REAL_OF_NUM_LE;
2728 REAL_OF_NUM_LT] THEN
2729 SIMP_TAC[ISQRT_WORKS; LT_IMP_LE] THEN
2730 UNDISCH_TAC `50 <= n` THEN ARITH_TAC;
2732 SIMP_TAC[LN_POW; REAL_POS; REAL_ARITH `&0 <= x ==> &0 < x + &1`] THEN
2733 GEN_REWRITE_TAC LAND_CONV [REAL_MUL_SYM] THEN
2734 SIMP_TAC[GSYM REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
2735 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
2736 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2737 MATCH_MP_TAC(REAL_ARITH `a - b <= b * (d - &1) ==> a <= b * d`) THEN
2738 ASM_SIMP_TAC[GSYM LN_DIV; REAL_ARITH `&0 < x ==> &0 < x + &1`;
2739 REAL_OF_NUM_LT; ARITH_RULE `0 < n <=> ~(n = 0)`] THEN
2740 REWRITE_TAC[real_div; REAL_ADD_RDISTRIB] THEN
2741 ASM_SIMP_TAC[REAL_MUL_RINV; REAL_OF_NUM_EQ; ARITH; REAL_MUL_LID] THEN
2742 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `inv(&(ISQRT n))` THEN
2743 ASM_SIMP_TAC[LN_LE; REAL_POS; REAL_LE_INV_EQ] THEN
2744 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2745 REWRITE_TAC[real_div; REAL_MUL_LID] THEN REWRITE_TAC[GSYM real_div] THEN
2746 SIMP_TAC[REAL_LE_RDIV_EQ; REAL_OF_NUM_LT; ARITH] THEN
2747 ONCE_REWRITE_TAC[REAL_MUL_SYM] THEN
2748 ASM_SIMP_TAC[GSYM real_div; REAL_LE_LDIV_EQ; REAL_OF_NUM_LT;
2749 ARITH_RULE `0 < n <=> ~(n = 0)`] THEN
2750 SUBGOAL_THEN `&7 <= &(ISQRT n)` MP_TAC THENL
2751 [REWRITE_TAC[REAL_OF_NUM_LE] THEN
2752 SUBGOAL_THEN `7 EXP 2 < (ISQRT n + 1) EXP 2` MP_TAC THENL
2753 [MATCH_MP_TAC LET_TRANS THEN EXISTS_TAC `n:num` THEN
2754 REWRITE_TAC[ISQRT_WORKS] THEN CONV_TAC NUM_REDUCE_CONV THEN
2755 UNDISCH_TAC `50 <= n` THEN ARITH_TAC;
2757 REWRITE_TAC[num_CONV `2`; EXP_MONO_LT_SUC] THEN ARITH_TAC;
2759 SPEC_TAC(`&(ISQRT n)`,`x:real`) THEN
2760 MATCH_MP_TAC OVERPOWER_LEMMA THEN
2763 (lhand(rator(rand(body(rand(lhand(rand(body(rand w))))))))) in
2765 GEN_REWRITE_TAC (LAND_CONV o TOP_DEPTH_CONV)
2766 [REAL_MUL_LZERO; REAL_ADD_LID; REAL_ADD_RID;
2767 REAL_MUL_RID; REAL_MUL_LID] THEN
2768 SIMP_TAC[REAL_MUL_LINV; REAL_LT_IMP_NZ] THEN
2770 let tm = mk_abs(`x:real`,rand(rator(rand(body(rand(lhand w)))))) in
2771 DISCH_TAC THEN EXISTS_TAC tm) THEN
2773 [CONV_TAC REAL_RAT_REDUCE_CONV THEN REWRITE_TAC[real_sub] THEN
2774 CONV_TAC(ONCE_DEPTH_CONV LN_N2_CONV) THEN
2775 CONV_TAC REALCALC_REL_CONV;
2777 REWRITE_TAC[] THEN CONJ_TAC THENL
2779 DISCH_THEN(fun th -> FIRST_ASSUM MATCH_MP_TAC THEN MP_TAC th) THEN
2782 X_GEN_TAC `x:real` THEN REWRITE_TAC[REAL_SUB_RZERO] THEN
2783 SIMP_TAC[LN_POS; REAL_LE_ADD; REAL_POS; REAL_ARITH `&7 <= x ==> &1 <= x`]);;
2785 (* ------------------------------------------------------------------------- *)
2786 (* Hence a bound by wellfounded induction. *)
2787 (* ------------------------------------------------------------------------- *)
2789 let PII_UBOUND_5 = prove
2790 (`!n. 3 <= n ==> pii(n) <= &5 * (&n / ln(&n))`,
2791 REWRITE_TAC[real_div; REAL_MUL_ASSOC] THEN
2792 SIMP_TAC[GSYM real_div; REAL_LE_RDIV_EQ; LN_POS_LT; REAL_OF_NUM_LT;
2793 ARITH_RULE `3 <= n ==> 1 < n`] THEN
2794 GEN_REWRITE_TAC (BINDER_CONV o RAND_CONV o LAND_CONV) [REAL_MUL_SYM] THEN
2795 MATCH_MP_TAC num_WF THEN X_GEN_TAC `n:num` THEN
2796 ASM_CASES_TAC `n < 50` THEN ASM_SIMP_TAC[PII_UBOUND_CASES_50] THEN
2797 DISCH_THEN(MP_TAC o SPEC `ISQRT n`) THEN
2798 RULE_ASSUM_TAC(REWRITE_RULE[NOT_LT]) THEN
2799 SUBGOAL_THEN `7 <= ISQRT n` ASSUME_TAC THENL
2800 [REWRITE_TAC[REAL_OF_NUM_LE] THEN
2801 SUBGOAL_THEN `7 EXP 2 < (ISQRT n + 1) EXP 2` MP_TAC THENL
2802 [MATCH_MP_TAC LET_TRANS THEN EXISTS_TAC `n:num` THEN
2803 REWRITE_TAC[ISQRT_WORKS] THEN CONV_TAC NUM_REDUCE_CONV THEN
2804 UNDISCH_TAC `50 <= n` THEN ARITH_TAC;
2806 REWRITE_TAC[num_CONV `2`; EXP_MONO_LT_SUC] THEN ARITH_TAC;
2808 ASM_SIMP_TAC[ARITH_RULE `7 <= n ==> 3 <= n`;
2809 ARITH_RULE `50 <= n ==> 3 <= n`] THEN
2811 [SUBGOAL_THEN `(ISQRT n) EXP 2 < n EXP 2` MP_TAC THENL
2812 [MATCH_MP_TAC LET_TRANS THEN EXISTS_TAC `n:num` THEN
2813 REWRITE_TAC[ISQRT_WORKS] THEN REWRITE_TAC[EXP_2] THEN
2814 MATCH_MP_TAC(ARITH_RULE `1 * n < m ==> n < m`) THEN
2815 REWRITE_TAC[LT_MULT_RCANCEL] THEN
2816 UNDISCH_TAC `50 <= n` THEN ARITH_TAC;
2818 REWRITE_TAC[num_CONV `2`; EXP_MONO_LT_SUC];
2821 FIRST_ASSUM(MP_TAC o MATCH_MP PII_ISQRT_INDUCT) THEN
2822 MATCH_MP_TAC(REAL_ARITH `a <= b ==> x <= a ==> x <= b`) THEN
2823 MATCH_MP_TAC REAL_LE_TRANS THEN
2824 EXISTS_TAC `&9 / &4 * (&3 / &2 * &n + &5 * &(ISQRT n))` THEN
2826 [MATCH_MP_TAC REAL_LE_LMUL THEN CONV_TAC REAL_RAT_REDUCE_CONV THEN
2827 ASM_REWRITE_TAC[REAL_LE_LADD];
2829 MATCH_MP_TAC(REAL_ARITH
2830 `i * (a * c) <= n * (d - a * b) ==> a * (b * n + c * i) <= d * n`) THEN
2831 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2832 SIMP_TAC[GSYM REAL_LE_LDIV_EQ; REAL_LT_DIV; REAL_OF_NUM_LT; ARITH] THEN
2833 REWRITE_TAC[real_div; GSYM REAL_MUL_ASSOC] THEN
2834 CONV_TAC REAL_RAT_REDUCE_CONV THEN
2835 MATCH_MP_TAC REAL_LE_TRANS THEN EXISTS_TAC `&(ISQRT n) * &7` THEN
2837 [MATCH_MP_TAC REAL_LE_LMUL THEN REWRITE_TAC[REAL_POS] THEN
2838 CONV_TAC REAL_RAT_REDUCE_CONV;
2840 REWRITE_TAC[REAL_OF_NUM_MUL; REAL_OF_NUM_LE] THEN
2841 MATCH_MP_TAC LE_TRANS THEN EXISTS_TAC `ISQRT n * ISQRT n` THEN CONJ_TAC THENL
2842 [ASM_REWRITE_TAC[LE_MULT_LCANCEL];
2843 REWRITE_TAC[GSYM EXP_2; ISQRT_WORKS]]);;