1 (* ========================================================================= *)
2 (* Definability in arithmetic of important notions. *)
3 (* ========================================================================= *)
7 (* ------------------------------------------------------------------------- *)
8 (* Pairing operation. *)
9 (* ------------------------------------------------------------------------- *)
11 let NPAIR = new_definition
12 `NPAIR x y = (x + y) EXP 2 + x + 1`;;
14 let NPAIR_NONZERO = prove
15 (`!x y. ~(NPAIR x y = 0)`,
16 REWRITE_TAC[NPAIR; ADD_EQ_0; ARITH]);;
18 let NPAIR_INJ_LEMMA = prove
19 (`x1 + y1 < x2 + y2 ==> NPAIR x1 y1 < NPAIR x2 y2`,
20 STRIP_TAC THEN REWRITE_TAC[NPAIR; EXP_2] THEN
21 REWRITE_TAC[ARITH_RULE `x + y + 1 < u + v + 1 <=> x + y < u + v`] THEN
22 MATCH_MP_TAC LTE_TRANS THEN
23 EXISTS_TAC `SUC(x1 + y1) * SUC(x1 + y1)` THEN CONJ_TAC THENL
24 [ARITH_TAC; ASM_MESON_TAC[LE_TRANS; LE_ADD; LE_MULT2; LE_SUC_LT]]);;
27 (`(NPAIR x y = NPAIR x' y') <=> (x = x') /\ (y = y')`,
28 EQ_TAC THEN STRIP_TAC THEN ASM_REWRITE_TAC[] THEN
29 SUBGOAL_THEN `x' + y' = x + y` ASSUME_TAC THENL
30 [ASM_MESON_TAC[LT_CASES; NPAIR_INJ_LEMMA; LT_REFL];
31 UNDISCH_TAC `NPAIR x y = NPAIR x' y'` THEN
32 UNDISCH_TAC `x' + y' = x + y` THEN
33 SIMP_TAC[NPAIR; EXP_2] THEN ARITH_TAC]);;
35 (* ------------------------------------------------------------------------- *)
37 (* ------------------------------------------------------------------------- *)
40 (`!x y. x < NPAIR x y /\ y < NPAIR x y`,
41 REPEAT GEN_TAC THEN REWRITE_TAC[NPAIR] THEN
42 REWRITE_TAC[ARITH_RULE `x < a + x + 1`] THEN
43 MATCH_MP_TAC LTE_TRANS THEN EXISTS_TAC `(x + y) + x + 1` THEN
44 REWRITE_TAC[LE_ADD_RCANCEL; EXP_2; LE_SQUARE_REFL] THEN
47 (* ------------------------------------------------------------------------- *)
48 (* Auxiliary concepts needed. NB: these are Delta so can be negated freely. *)
49 (* ------------------------------------------------------------------------- *)
51 let primepow = new_definition
52 `primepow p x <=> prime(p) /\ ?n. x = p EXP n`;;
54 let divides_DELTA = prove
55 (`m divides n <=> ?x. x <= n /\ n = m * x`,
56 REWRITE_TAC[divides] THEN ASM_CASES_TAC `m = 0` THENL
57 [ASM_REWRITE_TAC[MULT_CLAUSES] THEN MESON_TAC[LE_REFL]; ALL_TAC] THEN
58 AP_TERM_TAC THEN ABS_TAC THEN EQ_TAC THEN SIMP_TAC[] THEN
59 FIRST_ASSUM(MP_TAC o MATCH_MP (ARITH_RULE `~(m = 0) ==> 1 <= m`)) THEN
60 SIMP_TAC[LE_EXISTS; LEFT_IMP_EXISTS_THM;
61 RIGHT_ADD_DISTRIB; MULT_CLAUSES] THEN
64 let prime_DELTA = prove
65 (`prime(p) <=> 2 <= p /\ !n. n < p ==> n divides p ==> n = 1`,
66 ASM_CASES_TAC `p = 0` THEN ASM_REWRITE_TAC[ARITH; PRIME_0] THEN
67 ASM_CASES_TAC `p = 1` THEN ASM_REWRITE_TAC[ARITH; PRIME_1] THEN EQ_TAC THENL
68 [ASM_MESON_TAC[prime; LT_REFL; PRIME_GE_2];
69 ASM_MESON_TAC[prime; DIVIDES_LE; LE_LT]]);;
71 let primepow_DELTA = prove
73 prime(p) /\ ~(x = 0) /\
74 !z. z <= x ==> z divides x ==> z = 1 \/ p divides z`,
75 REWRITE_TAC[primepow; TAUT `a ==> b \/ c <=> a /\ ~b ==> c`] THEN
76 ASM_CASES_TAC `prime(p)` THEN
77 ASM_REWRITE_TAC[] THEN EQ_TAC THENL
78 [DISCH_THEN(X_CHOOSE_THEN `n:num` SUBST1_TAC) THEN
79 ASM_REWRITE_TAC[EXP_EQ_0] THEN
80 ASM_CASES_TAC `p = 0` THEN ASM_REWRITE_TAC[] THENL
81 [ASM_MESON_TAC[PRIME_0]; ALL_TAC] THEN
83 FIRST_ASSUM(MP_TAC o SPEC `z:num` o MATCH_MP PRIME_COPRIME) THEN
84 ASM_REWRITE_TAC[] THEN
85 ASM_CASES_TAC `p divides z` THEN ASM_REWRITE_TAC[] THEN
86 ONCE_REWRITE_TAC[COPRIME_SYM] THEN
87 DISCH_THEN(MP_TAC o SPEC `n:num` o MATCH_MP COPRIME_EXP) THEN
88 ASM_MESON_TAC[COPRIME; DIVIDES_REFL];
89 SPEC_TAC(`x:num`,`x:num`) THEN MATCH_MP_TAC num_WF THEN
90 REPEAT STRIP_TAC THEN ASM_CASES_TAC `x = 1` THENL
91 [EXISTS_TAC `0` THEN ASM_REWRITE_TAC[EXP]; ALL_TAC] THEN
92 FIRST_ASSUM(X_CHOOSE_THEN `q:num` MP_TAC o MATCH_MP PRIME_FACTOR) THEN
94 UNDISCH_TAC `!z. z <= x ==> z divides x /\ ~(z = 1) ==> p divides z` THEN
95 DISCH_THEN(fun th -> ASSUME_TAC th THEN MP_TAC th) THEN
96 DISCH_THEN(MP_TAC o SPEC `q:num`) THEN ASM_REWRITE_TAC[] THEN
97 ASM_CASES_TAC `q = 1` THENL [ASM_MESON_TAC[PRIME_1]; ALL_TAC] THEN
98 ASM_REWRITE_TAC[] THEN
99 SUBGOAL_THEN `q <= x` ASSUME_TAC THENL
100 [ASM_MESON_TAC[DIVIDES_LE]; ASM_REWRITE_TAC[]] THEN
101 SUBGOAL_THEN `p divides x` MP_TAC THENL
102 [ASM_MESON_TAC[DIVIDES_TRANS]; ALL_TAC] THEN
103 REWRITE_TAC[divides] THEN DISCH_THEN(X_CHOOSE_TAC `y:num`) THEN
104 SUBGOAL_THEN `y < x` (ANTE_RES_THEN MP_TAC) THENL
105 [MATCH_MP_TAC PRIME_FACTOR_LT THEN
106 EXISTS_TAC `p:num` THEN ASM_REWRITE_TAC[]; ALL_TAC] THEN
107 ASM_CASES_TAC `y = 0` THENL
108 [UNDISCH_TAC `x = p * y` THEN ASM_REWRITE_TAC[MULT_CLAUSES]; ALL_TAC] THEN
109 ASM_REWRITE_TAC[] THEN
110 SUBGOAL_THEN `!z. z <= y ==> z divides y /\ ~(z = 1) ==> p divides z`
111 (fun th -> REWRITE_TAC[th]) THENL
112 [REPEAT STRIP_TAC THEN
113 FIRST_ASSUM(MATCH_MP_TAC o REWRITE_RULE
115 REPEAT CONJ_TAC THENL
116 [MATCH_MP_TAC LE_TRANS THEN EXISTS_TAC `y:num` THEN
117 ASM_REWRITE_TAC[] THEN
118 GEN_REWRITE_TAC LAND_CONV [ARITH_RULE `y = 1 * y`] THEN
119 REWRITE_TAC[LE_MULT_RCANCEL] THEN
120 ASM_REWRITE_TAC[GSYM NOT_LT] THEN
121 REWRITE_TAC[num_CONV `1`; LT; DE_MORGAN_THM] THEN
122 ASM_MESON_TAC[PRIME_0; PRIME_1];
123 ASM_REWRITE_TAC[] THEN MATCH_MP_TAC DIVIDES_LMUL THEN
126 DISCH_THEN(X_CHOOSE_THEN `n:num` SUBST1_TAC) THEN
127 EXISTS_TAC `SUC n` THEN ASM_REWRITE_TAC[EXP]]]);;
129 (* ------------------------------------------------------------------------- *)
130 (* Sigma-representability of reflexive transitive closure. *)
131 (* ------------------------------------------------------------------------- *)
133 let PSEQ = new_recursive_definition num_RECURSION
134 `(PSEQ p f m 0 = 0) /\
135 (PSEQ p f m (SUC n) = f m + p * PSEQ p f (SUC m) n)`;;
137 let PSEQ_SPLIT = prove
139 PSEQ p f m (n + r) = PSEQ p f m n + p EXP n * PSEQ p f (m + n) r`,
140 GEN_TAC THEN GEN_TAC THEN
141 INDUCT_TAC THEN REWRITE_TAC[ADD_CLAUSES; EXP; MULT_CLAUSES; PSEQ] THEN
142 ASM_REWRITE_TAC[GSYM ADD_ASSOC; EQ_ADD_LCANCEL] THEN
143 REWRITE_TAC[LEFT_ADD_DISTRIB; MULT_AC; ADD_CLAUSES]);;
146 (`PSEQ p f m 1 = f m`,
147 REWRITE_TAC[num_CONV `1`; ADD_CLAUSES; MULT_CLAUSES; PSEQ]);;
149 let PSEQ_BOUND = prove
150 (`!n. ~(p = 0) /\ (!i. i < n ==> f i < p) ==> PSEQ p f 0 n < p EXP n`,
151 ASM_CASES_TAC `p = 0` THEN ASM_REWRITE_TAC[] THEN
152 INDUCT_TAC THENL [REWRITE_TAC[PSEQ; EXP; ARITH]; ALL_TAC] THEN
154 MP_TAC(SPECL [`f:num->num`; `p:num`; `n:num`; `0`; `1`]
156 SIMP_TAC[ADD1; ADD_CLAUSES] THEN REPEAT STRIP_TAC THEN
157 MATCH_MP_TAC LTE_TRANS THEN
158 EXISTS_TAC `p EXP n + p EXP n * PSEQ p f n 1` THEN
159 ASM_SIMP_TAC[LT_ADD_RCANCEL; ARITH_RULE `i < n ==> i < SUC n`] THEN
160 REWRITE_TAC[ARITH_RULE `p + p * q = p * (q + 1)`] THEN
161 ASM_REWRITE_TAC[EXP_ADD; LE_MULT_LCANCEL; EXP_EQ_0] THEN
162 MATCH_MP_TAC(ARITH_RULE `x < p ==> x + 1 <= p`) THEN
163 ASM_SIMP_TAC[EXP_1; PSEQ_1; LT]);;
165 let RELPOW_LEMMA_1 = prove
168 (!i. i < n ==> R (f i) (f(SUC i)))
169 ==> ?p. (?i. i <= n /\ p <= SUC(FACT(f i))) /\
171 (?m. m < p EXP (SUC n) /\
173 (?qx. m = x + p * qx) /\
174 (?ry. ry < p EXP n /\ (m = ry + p EXP n * y)) /\
183 r + q * (a + p * (b + p * s))))`,
184 REPEAT STRIP_TAC THEN
185 SUBGOAL_THEN `?j. j <= n /\ !i. i <= n ==> f i <= f j` MP_TAC THENL
186 [SPEC_TAC(`n:num`,`n:num`) THEN POP_ASSUM_LIST(K ALL_TAC) THEN
188 [SIMP_TAC[LE] THEN MESON_TAC[LE_REFL]; ALL_TAC] THEN
189 FIRST_ASSUM(X_CHOOSE_THEN `j:num` STRIP_ASSUME_TAC) THEN
190 DISJ_CASES_TAC(ARITH_RULE `f(SUC n) <= f(j) \/ f(j) <= f(SUC n)`) THENL
191 [EXISTS_TAC `j:num` THEN
192 ASM_SIMP_TAC[ARITH_RULE `j <= n ==> j <= SUC n`] THEN
193 REWRITE_TAC[LE] THEN REPEAT STRIP_TAC THEN
194 ASM_SIMP_TAC[] THEN ASM_MESON_TAC[];
195 EXISTS_TAC `SUC n` THEN REWRITE_TAC[LE_REFL] THEN
196 REWRITE_TAC[LE] THEN REPEAT STRIP_TAC THEN
197 ASM_SIMP_TAC[LE_REFL] THEN ASM_MESON_TAC[LE_TRANS]];
199 DISCH_THEN(X_CHOOSE_THEN `ibig:num` STRIP_ASSUME_TAC) THEN
200 MP_TAC(SPEC `(f:num->num) ibig` EUCLID_BOUND) THEN
201 DISCH_THEN(X_CHOOSE_THEN `p:num` STRIP_ASSUME_TAC) THEN
202 EXISTS_TAC `p:num` THEN CONJ_TAC THENL
203 [EXISTS_TAC `ibig:num` THEN ASM_REWRITE_TAC[]; ALL_TAC] THEN
204 SUBGOAL_THEN `~(p = 0)` ASSUME_TAC THENL
205 [ASM_MESON_TAC[PRIME_0]; ALL_TAC] THEN
206 CONJ_TAC THENL [FIRST_ASSUM ACCEPT_TAC; ALL_TAC] THEN
207 SUBGOAL_THEN `!i. i <= n ==> f i < p` ASSUME_TAC THENL
208 [ASM_MESON_TAC[LET_TRANS]; ALL_TAC] THEN
209 EXISTS_TAC `PSEQ p f 0 (SUC n)` THEN CONJ_TAC THENL
210 [MATCH_MP_TAC PSEQ_BOUND THEN ASM_SIMP_TAC[LT_SUC_LE]; ALL_TAC] THEN
211 CONJ_TAC THENL [ASM_MESON_TAC[LE_0]; ALL_TAC] THEN
212 CONJ_TAC THENL [ASM_MESON_TAC[LE_REFL]; ALL_TAC] THEN
213 REPEAT CONJ_TAC THENL
214 [ASM_REWRITE_TAC[PSEQ] THEN MESON_TAC[];
215 MP_TAC(SPECL [`f:num->num`; `p:num`; `n:num`; `0`; `1`] PSEQ_SPLIT) THEN
216 ASM_SIMP_TAC[ADD1; ADD_CLAUSES] THEN
217 DISCH_THEN(K ALL_TAC) THEN EXISTS_TAC `PSEQ p f 0 n` THEN
218 ASM_SIMP_TAC[PSEQ_BOUND; PSEQ_1; LT_IMP_LE];
220 ONCE_REWRITE_TAC[TAUT `a ==> b ==> c <=> b ==> a ==> c`] THEN
221 ASM_SIMP_TAC[primepow; LEFT_IMP_EXISTS_THM] THEN
222 GEN_TAC THEN X_GEN_TAC `i:num` THEN DISCH_THEN(K ALL_TAC) THEN
223 ASM_REWRITE_TAC[LT_EXP] THEN STRIP_TAC THEN
224 MP_TAC(SPECL [`f:num->num`; `p:num`; `i:num`; `0`; `SUC n - i`]
226 ASM_SIMP_TAC[ARITH_RULE `i < n ==> (i + SUC n - i = SUC n)`] THEN
227 DISCH_THEN(K ALL_TAC) THEN
228 EXISTS_TAC `PSEQ p f 0 i` THEN REWRITE_TAC[EQ_ADD_LCANCEL] THEN
229 ASM_REWRITE_TAC[EQ_MULT_LCANCEL; EXP_EQ_0; ADD_CLAUSES] THEN
231 [ASM_MESON_TAC[PSEQ_BOUND; LT_TRANS; LT_IMP_LE]; ALL_TAC] THEN
232 MP_TAC(SPECL [`f:num->num`; `p:num`; `1`; `i:num`; `n - i`]
234 ASM_SIMP_TAC[ARITH_RULE `i < n ==> (1 + n - i = SUC n - i)`] THEN
235 DISCH_THEN(K ALL_TAC) THEN EXISTS_TAC `PSEQ p f i 1` THEN
236 ASM_REWRITE_TAC[EQ_ADD_LCANCEL; EQ_MULT_LCANCEL; EXP_1] THEN
237 ASM_SIMP_TAC[PSEQ_1; LT_IMP_LE] THEN
238 MP_TAC(SPECL [`f:num->num`; `p:num`; `1`; `i + 1`; `n - i - 1`]
240 ASM_SIMP_TAC[ARITH_RULE `i < n ==> (1 + n - i - 1 = n - i)`] THEN
241 DISCH_THEN(K ALL_TAC) THEN EXISTS_TAC `PSEQ p f (i + 1) 1` THEN
242 ASM_REWRITE_TAC[EQ_ADD_LCANCEL; EQ_MULT_LCANCEL; EXP_1] THEN
243 ASM_SIMP_TAC[PSEQ_1; ARITH_RULE `i < n ==> i + 1 <= n`] THEN
244 ASM_SIMP_TAC[GSYM ADD1] THEN REWRITE_TAC[ADD1] THEN
245 ONCE_REWRITE_TAC[CONJ_SYM] THEN REWRITE_TAC[UNWIND_THM1] THEN
246 REWRITE_TAC[LEFT_ADD_DISTRIB; MULT_ASSOC; ADD_ASSOC] THEN
247 MATCH_MP_TAC(ARITH_RULE `1 * a <= c ==> a <= b + c`) THEN
248 REWRITE_TAC[LE_MULT_RCANCEL] THEN DISJ1_TAC THEN
249 ASM_REWRITE_TAC[ARITH_RULE `1 <= x <=> ~(x = 0)`; MULT_EQ_0; EXP_EQ_0]);;
251 let RELPOW_LEMMA_2 = prove
252 (`prime p /\ x < p /\ y < p /\
253 (?qx. m = x + p * qx) /\
254 (?ry. ry < p EXP n /\ (m = ry + p EXP n * y)) /\
257 ==> ?r a b s. (m = r + q * (a + p * (b + p * s))) /\
258 r < q /\ a < p /\ b < p /\ R a b)
260 STRIP_TAC THEN REWRITE_TAC[RELPOW_SEQUENCE] THEN
261 EXISTS_TAC `\i. (m DIV (p EXP i)) MOD p` THEN
262 SUBGOAL_THEN `~(p = 0)` ASSUME_TAC THENL
263 [ASM_MESON_TAC[PRIME_0]; ALL_TAC] THEN
264 REWRITE_TAC[EXP; DIV_1] THEN REPEAT CONJ_TAC THENL
265 [MATCH_MP_TAC MOD_UNIQ THEN EXISTS_TAC `qx:num` THEN
266 ASM_REWRITE_TAC[ADD_AC; MULT_AC];
267 MATCH_MP_TAC MOD_UNIQ THEN EXISTS_TAC `0` THEN
268 REWRITE_TAC[ASSUME `y < p`; MULT_CLAUSES; ADD_CLAUSES] THEN
269 MATCH_MP_TAC DIV_UNIQ THEN EXISTS_TAC `ry:num` THEN
270 REWRITE_TAC[ASSUME `m = ry + p EXP n * y`] THEN
271 ASM_REWRITE_TAC[ADD_AC; MULT_AC];
273 X_GEN_TAC `i:num` THEN DISCH_TAC THEN
274 FIRST_X_ASSUM(MP_TAC o SPEC `p EXP i`) THEN
275 ASM_SIMP_TAC[LT_EXP; PRIME_GE_2] THEN
276 ASM_REWRITE_TAC[primepow] THEN
277 W(C SUBGOAL_THEN (fun th -> REWRITE_TAC[th]) o funpow 2 lhand o snd) THENL
278 [MESON_TAC[]; ALL_TAC] THEN
279 DISCH_THEN(REPEAT_TCL CHOOSE_THEN MP_TAC) THEN
280 DISCH_THEN(CONJUNCTS_THEN2 SUBST1_TAC STRIP_ASSUME_TAC) THEN
281 UNDISCH_TAC `(R:num->num->bool) a b` THEN
282 MATCH_MP_TAC(TAUT `(b <=> a) ==> a ==> b`) THEN BINOP_TAC THENL
283 [MATCH_MP_TAC MOD_UNIQ THEN EXISTS_TAC `b + p * s` THEN
284 ASM_REWRITE_TAC[] THEN
285 MATCH_MP_TAC DIV_UNIQ THEN EXISTS_TAC `r:num` THEN ASM_REWRITE_TAC[] THEN
286 REWRITE_TAC[ADD_AC; MULT_AC];
287 MATCH_MP_TAC MOD_UNIQ THEN EXISTS_TAC `s:num` THEN ASM_REWRITE_TAC[] THEN
288 MATCH_MP_TAC DIV_UNIQ THEN EXISTS_TAC `r + a * p EXP i` THEN
290 [REWRITE_TAC[LEFT_ADD_DISTRIB; RIGHT_ADD_DISTRIB] THEN
291 REWRITE_TAC[ADD_AC; MULT_AC]; ALL_TAC] THEN
292 MATCH_MP_TAC LTE_TRANS THEN EXISTS_TAC `p EXP i + a * p EXP i` THEN
293 ASM_REWRITE_TAC[LT_ADD_RCANCEL] THEN
294 REWRITE_TAC[ARITH_RULE `p + q * p = (q + 1) * p`] THEN
295 ASM_REWRITE_TAC[LE_MULT_RCANCEL; EXP_EQ_0] THEN
296 UNDISCH_TAC `a < p` THEN ARITH_TAC]);;
298 let RELPOW_LEMMA = prove
300 ?m p. prime p /\ x < p /\ y < p /\
301 (?qx. m = x + p * qx) /\
302 (?ry. ry < p EXP n /\ (m = ry + p EXP n * y)) /\
305 ==> ?r a b s. (m = r + q * (a + p * (b + p * s))) /\
306 r < q /\ a < p /\ b < p /\ R a b`,
308 [ALL_TAC; REWRITE_TAC[RELPOW_LEMMA_2; LEFT_IMP_EXISTS_THM]] THEN
309 REWRITE_TAC[RELPOW_SEQUENCE] THEN
310 DISCH_THEN(CHOOSE_THEN(MP_TAC o GEN_ALL o MATCH_MP RELPOW_LEMMA_1)) THEN
311 REWRITE_TAC[RIGHT_AND_EXISTS_THM] THEN
312 GEN_REWRITE_TAC RAND_CONV [SWAP_EXISTS_THM] THEN
313 MATCH_MP_TAC MONO_EXISTS THEN
314 GEN_TAC THEN MATCH_MP_TAC MONO_EXISTS THEN
315 SIMP_TAC[] THEN MESON_TAC[]);;
317 let RTC_SIGMA = prove
319 ?m p Q. primepow p Q /\ x < p /\ y < p /\
320 (?s. m = x + p * s) /\
321 (?r. r < Q /\ (m = r + Q * y)) /\
324 ==> ?r a b s. (m = r + q * (a + p * (b + p * s))) /\
325 r < q /\ a < p /\ b < p /\ R a b`,
326 REWRITE_TAC[RTC_RELPOW] THEN EQ_TAC THENL
327 [DISCH_THEN(X_CHOOSE_THEN `n:num` MP_TAC) THEN
328 REWRITE_TAC[RELPOW_LEMMA] THEN
329 MATCH_MP_TAC MONO_EXISTS THEN GEN_TAC THEN
330 MATCH_MP_TAC MONO_EXISTS THEN GEN_TAC THEN
331 DISCH_TAC THEN EXISTS_TAC `p EXP n` THEN ASM_REWRITE_TAC[primepow] THEN
333 REWRITE_TAC[primepow] THEN
334 ONCE_REWRITE_TAC[TAUT `(a /\ b) /\ c <=> b /\ a /\ c`] THEN
335 REWRITE_TAC[GSYM primepow] THEN
336 GEN_REWRITE_TAC (LAND_CONV o funpow 3 BINDER_CONV)
337 [LEFT_AND_EXISTS_THM] THEN
338 GEN_REWRITE_TAC (LAND_CONV o BINDER_CONV o BINDER_CONV)
339 [SWAP_EXISTS_THM] THEN
340 REWRITE_TAC[UNWIND_THM2] THEN
341 GEN_REWRITE_TAC (LAND_CONV o BINDER_CONV) [SWAP_EXISTS_THM] THEN
342 GEN_REWRITE_TAC LAND_CONV [SWAP_EXISTS_THM] THEN
343 REWRITE_TAC[GSYM RELPOW_LEMMA]]);;
345 (* ------------------------------------------------------------------------- *)
346 (* Partially automate actual definability in object language. *)
347 (* ------------------------------------------------------------------------- *)
349 let arith_pair = new_definition
350 `arith_pair s t = (s ++ t) ** (s ++ t) ++ s ++ Suc Z`;;
352 let ARITH_PAIR = prove
353 (`!s t v. termval v (arith_pair s t) = NPAIR (termval v s) (termval v t)`,
354 REWRITE_TAC[termval; arith_pair; NPAIR; EXP_2; ARITH_SUC]);;
357 (`FVT(arith_pair s t) = FVT(s) UNION FVT(t)`,
358 REWRITE_TAC[arith_pair; FVT] THEN SET_TAC[]);;
361 let is_add = is_binop `(+):num->num->num`
362 and is_mul = is_binop `(*):num->num->num`
363 and is_le = is_binop `(<=):num->num->bool`
364 and is_lt = is_binop `(<):num->num->bool`
375 and oiff_tm = `(<->)`
376 and oimp_tm = `(-->)`
382 and numeral_tm = `numeral`
383 and assign_tm = `(|->):num->term->(num->term)->(num->term)`
384 and term_ty = `:term`
385 and form_ty = `:form`
387 and formsubst_tm = `formsubst`
388 and holdsv_tm = `holds v`
389 and v_tm = `v:num->num` in
390 let objectify1 fn op env tm = mk_comb(op,fn env (rand tm)) in
391 let objectify2 fn op env tm =
392 mk_comb(mk_comb(op,fn env (lhand tm)),fn env (rand tm)) in
394 let defs' = [TERMVAL_NUMERAL; ARITH_PAIR] @ defs in
395 let rec objectify_term env tm =
396 if is_var tm then mk_comb(ov_tm,apply env tm)
397 else if tm = zero_tm then oz_tm
398 else if is_numeral tm then mk_comb(numeral_tm,tm)
399 else if is_add tm then objectify2 objectify_term oadd_tm env tm
400 else if is_mul tm then objectify2 objectify_term omul_tm env tm
401 else if is_comb tm & rator tm = suc_tm
402 then objectify1 objectify_term osuc_tm env tm
404 let f,args = strip_comb tm in
405 let args' = map (objectify_term env) args in
407 (fun th -> fst(strip_comb(rand(snd(strip_forall(concl th))))) = f)
409 let l,r = dest_eq(snd(strip_forall(concl dth))) in
410 list_mk_comb(fst(strip_comb(rand l)),args')
412 let ty = itlist (mk_fun_ty o type_of) args' form_ty in
413 let v = mk_var(fst(dest_var f),ty) in
414 list_mk_comb(v,args') in
415 let rec objectify_formula env fm =
417 let x,bod = dest_forall fm in
418 let n = mk_small_numeral
419 (itlist (max o dest_small_numeral) (ran env) 0 + 1) in
420 mk_comb(mk_comb(oall_tm,n),objectify_formula ((x |-> n) env) bod)
421 else if is_exists fm then
422 let x,bod = dest_exists fm in
423 let n = mk_small_numeral
424 (itlist (max o dest_small_numeral) (ran env) 0 + 1) in
425 mk_comb(mk_comb(oex_tm,n),objectify_formula ((x |-> n) env) bod)
426 else if is_iff fm then objectify2 objectify_formula oiff_tm env fm
427 else if is_imp fm then objectify2 objectify_formula oimp_tm env fm
428 else if is_conj fm then objectify2 objectify_formula oand_tm env fm
429 else if is_disj fm then objectify2 objectify_formula oor_tm env fm
430 else if is_neg fm then objectify1 objectify_formula onot_tm env fm
431 else if is_le fm then objectify2 objectify_term ole_tm env fm
432 else if is_lt fm then objectify2 objectify_term olt_tm env fm
433 else if is_eq fm then objectify2 objectify_term oeq_tm env fm
434 else objectify_term env fm in
436 let ptm,tm = dest_eq(snd(strip_forall(concl th))) in
437 let vs = filter (fun v -> type_of v = num_ty) (snd(strip_comb ptm)) in
438 let ns = 1--(length vs) in
439 let env = itlist2 (fun v n -> v |-> mk_small_numeral n) vs ns undefined in
440 let otm = objectify_formula env tm in
441 let vs' = map (fun v -> mk_var(fst(dest_var v),term_ty)) vs in
443 (fun v n a -> mk_comb(mk_comb(mk_comb(assign_tm,mk_small_numeral
446 let rside = mk_comb(mk_comb(formsubst_tm,stm),otm) in
447 let vs'' = subtract (frees rside) vs' @ vs' in
448 let lty = itlist (mk_fun_ty o type_of) vs'' (type_of rside) in
449 let lside = list_mk_comb(mk_var(nam,lty),vs'') in
450 let def = mk_eq(lside,rside) in
451 let dth = new_definition def in
452 let clside = lhs(snd(strip_forall(concl dth))) in
453 let etm = mk_comb(holdsv_tm,clside) in
455 (REWRITE_CONV ([dth; holds; HOLDS_FORMSUBST] @ defs') THENC
456 REWRITE_CONV [termval; ARITH_EQ; o_THM; valmod] THENC
457 GEN_REWRITE_CONV I [GSYM th]) etm in
458 dth,DISCH_ALL (GENL (v_tm::vs') thm);;
460 (* ------------------------------------------------------------------------- *)
461 (* Some sort of common tactic for free variables. *)
462 (* ------------------------------------------------------------------------- *)
466 [FV; FORMSUBST_FV; FVT; TERMSUBST_FVT; IN_ELIM_THM;
467 NOT_IN_EMPTY; IN_UNION; IN_DELETE; IN_SING]
469 REWRITE_TAC[DISJ_ACI; TAUT `(a \/ b) /\ c <=> a /\ c \/ b /\ c`] THEN
470 REWRITE_TAC[EXISTS_OR_THM; GSYM CONJ_ASSOC; UNWIND_THM2; ARITH_EQ] THEN
471 REWRITE_TAC[valmod; ARITH_EQ; FVT] THEN REWRITE_TAC[DISJ_ACI] in
472 REPEAT STRIP_TAC THEN GEN_REWRITE_TAC I [EXTENSION] THEN
473 ASM_REWRITE_TAC ths' THEN tac THEN ASM_SIMP_TAC ths' THEN tac;;
475 (* ------------------------------------------------------------------------- *)
476 (* So do the formula-level stuff (more) automatically. *)
477 (* ------------------------------------------------------------------------- *)
479 let arith_divides,ARITH_DIVIDES =
480 OBJECTIFY [] "arith_divides" divides_DELTA;;
482 let FV_DIVIDES = prove
483 (`!s t. FV(arith_divides s t) = FVT(s) UNION FVT(t)`,
484 FV_TAC[arith_divides]);;
486 let arith_prime,ARITH_PRIME =
487 OBJECTIFY [ARITH_DIVIDES] "arith_prime" prime_DELTA;;
490 (`!t. FV(arith_prime t) = FVT(t)`,
491 FV_TAC[arith_prime; FVT_NUMERAL; FV_DIVIDES]);;
493 let arith_primepow,ARITH_PRIMEPOW =
494 OBJECTIFY [ARITH_PRIME; ARITH_DIVIDES] "arith_primepow" primepow_DELTA;;
496 let FV_PRIMEPOW = prove
497 (`!s t. FV(arith_primepow s t) = FVT(s) UNION FVT(t)`,
498 FV_TAC[arith_primepow; FVT_NUMERAL; FV_DIVIDES; FV_PRIME]);;
500 let arith_rtc,ARITH_RTC =
503 ASSUME `!v s t. holds v (R s t) <=> r (termval v s) (termval v t)`]
504 "arith_rtc" RTC_SIGMA;;
507 (`!R. (!s t. FV(R s t) = FVT(s) UNION FVT(t))
508 ==> !s t. FV(arith_rtc R s t) = FVT(s) UNION FVT(t)`,
509 FV_TAC[arith_rtc; FV_PRIMEPOW]);;
511 (* ------------------------------------------------------------------------- *)
512 (* Automate RTC constructions, including parametrized ones. *)
513 (* ------------------------------------------------------------------------- *)
517 (`(!v x y. holds v (f x y) <=> f' (termval v x) (termval v y))
518 ==> !g. (!n. g n = formsubst ((0 |-> n) V)
519 (arith_rtc f (numeral 0)
520 (arith_pair (V 0) (numeral 0))))
521 ==> !v n. holds v (g n) <=> RTC f' 0 (NPAIR (termval v n) 0)`,
522 DISCH_THEN(MP_TAC o MATCH_MP ARITH_RTC) THEN SIMP_TAC[HOLDS_FORMSUBST] THEN
523 REWRITE_TAC[termval; o_DEF; ARITH_EQ; valmod;
524 ARITH_PAIR; TERMVAL_NUMERAL]) in
526 let th1 = MATCH_MP pth def in
527 let v = fst(dest_forall(concl th1)) in
528 let th2 = SPEC (mk_var(nam,type_of v)) th1 in
529 let dth = new_definition (fst(dest_imp(concl th2))) in
530 dth,ONCE_REWRITE_RULE[GSYM th] (MATCH_MP th2 dth);;
532 let RTCP = new_definition
533 `RTCP R m x y <=> RTC (R m) x y`;;
535 let RTCP_SIGMA = REWRITE_RULE[GSYM RTCP]
536 (INST [`(R:num->num->num->bool) m`,`R:num->num->bool`] RTC_SIGMA);;
538 let arith_rtcp,ARITH_RTCP =
541 ASSUME `!v m s t. holds v (R m s t) <=>
542 r (termval v m) (termval v s) (termval v t)`]
543 "arith_rtcp" RTCP_SIGMA;;
545 let ARITH_RTC_PARAMETRIZED = REWRITE_RULE[RTCP] ARITH_RTCP;;
548 (`!R. (!s t u. FV(R s t u) = FVT(s) UNION FVT(t) UNION FVT(u))
549 ==> !s t u. FV(arith_rtcp R s t u) = FVT(s) UNION FVT(t) UNION FVT(u)`,
550 FV_TAC[arith_rtcp; FV_PRIMEPOW]);;
554 (`(!v m x y. holds v (f m x y) <=>
555 f' (termval v m) (termval v x) (termval v y))
556 ==> !g. (!m n. g m n = formsubst ((1 |-> m) ((0 |-> n) V))
557 (arith_rtcp f (V 1) (numeral 0)
558 (arith_pair (V 0) (numeral 0))))
559 ==> !v m n. holds v (g m n) <=>
560 RTC (f' (termval v m)) 0 (NPAIR (termval v n) 0)`,
561 DISCH_THEN(MP_TAC o MATCH_MP ARITH_RTC_PARAMETRIZED) THEN
562 SIMP_TAC[HOLDS_FORMSUBST] THEN
563 REWRITE_TAC[termval; o_DEF; ARITH_EQ; valmod;
564 ARITH_PAIR; TERMVAL_NUMERAL]) in
566 let th1 = MATCH_MP pth def in
567 let v = fst(dest_forall(concl th1)) in
568 let th2 = SPEC (mk_var(nam,type_of v)) th1 in
569 let dth = new_definition (fst(dest_imp(concl th2))) in
570 dth,ONCE_REWRITE_RULE[GSYM th] (MATCH_MP th2 dth);;
572 (* ------------------------------------------------------------------------- *)
573 (* Generic result about primitive recursion. *)
574 (* ------------------------------------------------------------------------- *)
576 let PRIMREC_SIGMA = prove
578 (!n. fn (SUC n) = f (fn n) n)
579 ==> !x y. RTC (\x y. ?n r. (x = NPAIR n r) /\ (y = NPAIR (SUC n) (f r n)))
580 (NPAIR 0 e) (NPAIR x y) <=>
582 REPEAT GEN_TAC THEN STRIP_TAC THEN INDUCT_TAC THEN
583 ONCE_REWRITE_TAC[RTC_CASES_L] THEN ASM_REWRITE_TAC[NPAIR_INJ; NOT_SUC] THEN
584 REWRITE_TAC[SUC_INJ; RIGHT_AND_EXISTS_THM] THEN GEN_TAC THEN
585 ONCE_REWRITE_TAC[SWAP_EXISTS_THM] THEN
586 GEN_REWRITE_TAC (LAND_CONV o BINDER_CONV) [SWAP_EXISTS_THM] THEN
587 ONCE_REWRITE_TAC[TAUT `a /\ b /\ c <=> b /\ a /\ c`] THEN
588 ASM_REWRITE_TAC[UNWIND_THM2] THEN ASM_MESON_TAC[]);;
590 let arith_primrecstep = new_definition
591 `arith_primrecstep R s t =
592 (formsubst ((0 |-> s) ((1 |-> t) V))
594 (V 0 === arith_pair (V 2) (V 3) &&
595 V 1 === arith_pair (Suc(V 2)) (V 4) &&
596 R (V 3) (V 2) (V 4))))))`;;
598 let ARITH_PRIMRECSTEP = prove
599 (`(!v x y z. holds v (R x y z) <=>
600 (f (termval v x) (termval v y) = termval v z))
601 ==> !v s t. holds v (arith_primrecstep R s t) <=>
602 ?n r. (termval v s = NPAIR n r) /\
603 (termval v t = NPAIR (SUC n) (f r n))`,
605 ASM_REWRITE_TAC[arith_primrecstep; holds; HOLDS_FORMSUBST] THEN
606 ASM_REWRITE_TAC[termval; valmod; o_DEF; ARITH_EQ; ARITH_PAIR] THEN
609 let FV_PRIMRECSTEP = prove
610 (`!R. (!s t u. FV(R s t u) SUBSET (FVT(s) UNION FVT(t) UNION FVT(u)))
611 ==> !s t. FV(arith_primrecstep R s t) = FVT(s) UNION FVT(t)`,
612 REWRITE_TAC[SUBSET; IN_UNION] THEN FV_TAC[arith_primrecstep; FVT_PAIR] THEN
613 GEN_TAC THEN MATCH_MP_TAC(TAUT `~a ==> (a \/ b <=> b)`) THEN
614 DISCH_THEN(CHOOSE_THEN
615 (CONJUNCTS_THEN2(ANTE_RES_THEN MP_TAC) ASSUME_TAC)) THEN
616 ASM_REWRITE_TAC[FVT; IN_SING]);;
618 let arith_primrec = new_definition
619 `arith_primrec R c s t =
620 arith_rtc (arith_primrecstep R)
621 (arith_pair Z c) (arith_pair s t)`;;
623 let ARITH_PRIMREC = prove
625 (fn 0 = e) /\ (!n. fn (SUC n) = f (fn n) n) /\
626 (!v. termval v c = e) /\
627 (!v x y z. holds v (R x y z) <=>
628 (f (termval v x) (termval v y) = termval v z))
629 ==> !v s t. holds v (arith_primrec R c s t) <=>
630 (fn(termval v s) = termval v t)`,
631 REPEAT STRIP_TAC THEN
632 FIRST_ASSUM(MP_TAC o MATCH_MP ARITH_PRIMRECSTEP) THEN
633 DISCH_THEN(MP_TAC o MATCH_MP ARITH_RTC) THEN
634 CONV_TAC(TOP_DEPTH_CONV ETA_CONV) THEN
635 SIMP_TAC[arith_primrec; ARITH_PAIR; termval] THEN
636 ASM_SIMP_TAC[PRIMREC_SIGMA]);;
638 let FV_PRIMREC = prove
639 (`!R c. (FVT c = {}) /\
640 (!s t u. FV(R s t u) SUBSET (FVT(s) UNION FVT(t) UNION FVT(u)))
641 ==> !s t. FV(arith_primrec R c s t) = FVT(s) UNION FVT(t)`,
642 REPEAT GEN_TAC THEN DISCH_TAC THEN REWRITE_TAC[arith_primrec] THEN
643 ASM_SIMP_TAC[FV_RTC; FVT_PAIR; FV_PRIMRECSTEP;
644 UNION_EMPTY; UNION_ACI; FVT]);;