1 (* ========================================================================= *)
2 (* Definition of finite Cartesian product types. *)
4 (* (c) Copyright, John Harrison 1998-2007 *)
5 (* ========================================================================= *)
9 (* ------------------------------------------------------------------------- *)
10 (* Association of a number with an indexing type. *)
11 (* ------------------------------------------------------------------------- *)
13 let dimindex = new_definition
14 `dimindex(s:A->bool) = if FINITE(:A) then CARD(:A) else 1`;;
16 let DIMINDEX_NONZERO = prove
17 (`!s:A->bool. ~(dimindex(s) = 0)`,
18 GEN_TAC THEN REWRITE_TAC[dimindex] THEN
19 COND_CASES_TAC THEN ASM_SIMP_TAC[CARD_EQ_0; ARITH] THEN SET_TAC[]);;
21 let DIMINDEX_GE_1 = prove
22 (`!s:A->bool. 1 <= dimindex(s)`,
23 REWRITE_TAC[ARITH_RULE `1 <= x <=> ~(x = 0)`; DIMINDEX_NONZERO]);;
25 let DIMINDEX_UNIV = prove
26 (`!s. dimindex(s:A->bool) = dimindex(:A)`,
27 REWRITE_TAC[dimindex]);;
29 let DIMINDEX_UNIQUE = prove
30 (`(:A) HAS_SIZE n ==> dimindex(:A) = n`,
31 MESON_TAC[dimindex; HAS_SIZE]);;
33 (* ------------------------------------------------------------------------- *)
34 (* An indexing type with that size, parametrized by base type. *)
35 (* ------------------------------------------------------------------------- *)
37 let finite_image_tybij =
38 new_type_definition "finite_image" ("finite_index","dest_finite_image")
40 (`?x. x IN 1..dimindex(:A)`,
41 EXISTS_TAC `1` THEN REWRITE_TAC[IN_NUMSEG; LE_REFL; DIMINDEX_GE_1]));;
43 let FINITE_IMAGE_IMAGE = prove
44 (`UNIV:(A)finite_image->bool = IMAGE finite_index (1..dimindex(:A))`,
45 REWRITE_TAC[EXTENSION; IN_UNIV; IN_IMAGE] THEN
46 MESON_TAC[finite_image_tybij]);;
48 (* ------------------------------------------------------------------------- *)
49 (* Dimension of such a type, and indexing over it. *)
50 (* ------------------------------------------------------------------------- *)
52 let HAS_SIZE_FINITE_IMAGE = prove
53 (`!s. (UNIV:(A)finite_image->bool) HAS_SIZE dimindex(s:A->bool)`,
54 GEN_TAC THEN SIMP_TAC[FINITE_IMAGE_IMAGE] THEN
55 MATCH_MP_TAC HAS_SIZE_IMAGE_INJ THEN
56 ONCE_REWRITE_TAC[DIMINDEX_UNIV] THEN REWRITE_TAC[HAS_SIZE_NUMSEG_1] THEN
57 MESON_TAC[finite_image_tybij]);;
59 let CARD_FINITE_IMAGE = prove
60 (`!s. CARD(UNIV:(A)finite_image->bool) = dimindex(s:A->bool)`,
61 MESON_TAC[HAS_SIZE_FINITE_IMAGE; HAS_SIZE]);;
63 let FINITE_FINITE_IMAGE = prove
64 (`FINITE(UNIV:(A)finite_image->bool)`,
65 MESON_TAC[HAS_SIZE_FINITE_IMAGE; HAS_SIZE]);;
67 let DIMINDEX_FINITE_IMAGE = prove
68 (`!s t. dimindex(s:(A)finite_image->bool) = dimindex(t:A->bool)`,
69 REPEAT GEN_TAC THEN GEN_REWRITE_TAC LAND_CONV [dimindex] THEN
70 MP_TAC(ISPEC `t:A->bool` HAS_SIZE_FINITE_IMAGE) THEN
71 SIMP_TAC[FINITE_FINITE_IMAGE; HAS_SIZE]);;
73 let FINITE_INDEX_WORKS = prove
75 ?!n. 1 <= n /\ n <= dimindex(:A) /\ (finite_index n = i)`,
76 REWRITE_TAC[CONJ_ASSOC; GSYM IN_NUMSEG] THEN MESON_TAC[finite_image_tybij]);;
78 let FINITE_INDEX_INJ = prove
79 (`!i j. 1 <= i /\ i <= dimindex(:A) /\
80 1 <= j /\ j <= dimindex(:A)
81 ==> ((finite_index i :A finite_image = finite_index j) <=>
83 MESON_TAC[FINITE_INDEX_WORKS]);;
85 let FORALL_FINITE_INDEX = prove
86 (`(!k:(N)finite_image. P k) =
87 (!i. 1 <= i /\ i <= dimindex(:N) ==> P(finite_index i))`,
88 MESON_TAC[FINITE_INDEX_WORKS]);;
90 (* ------------------------------------------------------------------------- *)
91 (* Hence finite Cartesian products, with indexing and lambdas. *)
92 (* ------------------------------------------------------------------------- *)
95 new_type_definition "cart" ("mk_cart","dest_cart")
96 (prove(`?f:(B)finite_image->A. T`,REWRITE_TAC[]));;
98 parse_as_infix("$",(25,"left"));;
100 let finite_index = new_definition
101 `x$i = dest_cart x (finite_index i)`;;
105 (x = y) <=> !i. 1 <= i /\ i <= dimindex(:B) ==> (x$i = y$i)`,
106 REPEAT GEN_TAC THEN REWRITE_TAC[finite_index; GSYM FORALL_FINITE_INDEX] THEN
107 REWRITE_TAC[GSYM FUN_EQ_THM; ETA_AX] THEN MESON_TAC[cart_tybij]);;
109 parse_as_binder "lambda";;
111 let lambda = new_definition
113 @f:A^B. !i. 1 <= i /\ i <= dimindex(:B) ==> (f$i = g i)`;;
115 let LAMBDA_BETA = prove
116 (`!i. 1 <= i /\ i <= dimindex(:B)
117 ==> (((lambda) g:A^B) $i = g i)`,
118 REWRITE_TAC[lambda] THEN CONV_TAC SELECT_CONV THEN
119 EXISTS_TAC `mk_cart(\k. g(@i. 1 <= i /\ i <= dimindex(:B) /\
120 (finite_index i = k))):A^B` THEN
121 REWRITE_TAC[finite_index; REWRITE_RULE[] cart_tybij] THEN
122 REPEAT STRIP_TAC THEN AP_TERM_TAC THEN MATCH_MP_TAC SELECT_UNIQUE THEN
123 GEN_TAC THEN REWRITE_TAC[] THEN
124 ASM_MESON_TAC[FINITE_INDEX_INJ; DIMINDEX_FINITE_IMAGE]);;
126 let LAMBDA_UNIQUE = prove
128 (!i. 1 <= i /\ i <= dimindex(:B) ==> (f$i = g i)) <=>
130 SIMP_TAC[CART_EQ; LAMBDA_BETA] THEN MESON_TAC[]);;
132 let LAMBDA_ETA = prove
133 (`!g. (lambda i. g$i) = g`,
134 REWRITE_TAC[CART_EQ; LAMBDA_BETA]);;
136 (* ------------------------------------------------------------------------- *)
137 (* For some purposes we can avoid side-conditions on the index. *)
138 (* ------------------------------------------------------------------------- *)
140 let FINITE_INDEX_INRANGE = prove
141 (`!i. ?k. 1 <= k /\ k <= dimindex(:N) /\ !x:A^N. x$i = x$k`,
142 REWRITE_TAC[finite_index] THEN MESON_TAC[FINITE_INDEX_WORKS]);;
144 let FINITE_INDEX_INRANGE_2 = prove
145 (`!i. ?k. 1 <= k /\ k <= dimindex(:N) /\
146 (!x:A^N. x$i = x$k) /\ (!y:B^N. y$i = y$k)`,
147 REWRITE_TAC[finite_index] THEN MESON_TAC[FINITE_INDEX_WORKS]);;
149 let CART_EQ_FULL = prove
150 (`!x y:A^N. x = y <=> !i. x$i = y$i`,
151 REPEAT GEN_TAC THEN EQ_TAC THEN SIMP_TAC[] THEN SIMP_TAC[CART_EQ]);;
153 (* ------------------------------------------------------------------------- *)
154 (* We need a non-standard sum to "paste" together Cartesian products. *)
155 (* ------------------------------------------------------------------------- *)
157 let finite_sum_tybij =
159 (`?x. x IN 1..(dimindex(:A) + dimindex(:B))`,
160 EXISTS_TAC `1` THEN SIMP_TAC[IN_NUMSEG; LE_REFL; DIMINDEX_GE_1;
161 ARITH_RULE `1 <= a ==> 1 <= a + b`]) in
162 new_type_definition "finite_sum" ("mk_finite_sum","dest_finite_sum") th;;
164 let pastecart = new_definition
165 `(pastecart:A^M->A^N->A^(M,N)finite_sum) f g =
166 lambda i. if i <= dimindex(:M) then f$i
167 else g$(i - dimindex(:M))`;;
169 let fstcart = new_definition
170 `(fstcart:A^(M,N)finite_sum->A^M) f = lambda i. f$i`;;
172 let sndcart = new_definition
173 `(sndcart:A^(M,N)finite_sum->A^N) f =
174 lambda i. f$(i + dimindex(:M))`;;
176 let FINITE_SUM_IMAGE = prove
177 (`UNIV:(A,B)finite_sum->bool =
178 IMAGE mk_finite_sum (1..(dimindex(:A)+dimindex(:B)))`,
179 REWRITE_TAC[EXTENSION; IN_UNIV; IN_IMAGE] THEN
180 MESON_TAC[finite_sum_tybij]);;
182 let DIMINDEX_HAS_SIZE_FINITE_SUM = prove
183 (`(UNIV:(M,N)finite_sum->bool) HAS_SIZE (dimindex(:M) + dimindex(:N))`,
184 SIMP_TAC[FINITE_SUM_IMAGE] THEN
185 MATCH_MP_TAC HAS_SIZE_IMAGE_INJ THEN
186 ONCE_REWRITE_TAC[DIMINDEX_UNIV] THEN REWRITE_TAC[HAS_SIZE_NUMSEG_1] THEN
187 MESON_TAC[finite_sum_tybij]);;
189 let DIMINDEX_FINITE_SUM = prove
190 (`dimindex(:(M,N)finite_sum) = dimindex(:M) + dimindex(:N)`,
191 GEN_REWRITE_TAC LAND_CONV [dimindex] THEN
192 REWRITE_TAC[REWRITE_RULE[HAS_SIZE] DIMINDEX_HAS_SIZE_FINITE_SUM]);;
194 let FSTCART_PASTECART = prove
195 (`!x y. fstcart(pastecart (x:A^M) (y:A^N)) = x`,
196 SIMP_TAC[pastecart; fstcart; CART_EQ; LAMBDA_BETA; DIMINDEX_FINITE_SUM;
197 ARITH_RULE `a <= b ==> a <= b + c`]);;
199 let SNDCART_PASTECART = prove
200 (`!x y. sndcart(pastecart (x:A^M) (y:A^N)) = y`,
201 SIMP_TAC[pastecart; sndcart; CART_EQ; LAMBDA_BETA] THEN REPEAT STRIP_TAC THEN
202 W(fun (_,w) -> MP_TAC (PART_MATCH (lhs o rand) LAMBDA_BETA (lhand w))) THEN
204 [REWRITE_TAC[DIMINDEX_FINITE_SUM] THEN MATCH_MP_TAC
205 (ARITH_RULE `1 <= i /\ i <= b ==> 1 <= i + a /\ i + a <= a + b`) THEN
207 DISCH_THEN SUBST1_TAC THEN REWRITE_TAC[] THEN
208 ASM_SIMP_TAC[ADD_SUB; ARITH_RULE `1 <= i ==> ~(i + a <= a)`]]);;
210 let PASTECART_FST_SND = prove
211 (`!z. pastecart (fstcart z) (sndcart z) = z`,
212 SIMP_TAC[pastecart; fstcart; sndcart; CART_EQ; LAMBDA_BETA] THEN
213 REPEAT GEN_TAC THEN COND_CASES_TAC THEN ASM_REWRITE_TAC[] THEN
214 ASM_SIMP_TAC[DIMINDEX_FINITE_SUM; LAMBDA_BETA;
215 ARITH_RULE `i <= a + b ==> i - a <= b`;
216 ARITH_RULE `~(i <= a) ==> 1 <= i - a`;
217 ARITH_RULE `~(i <= a) ==> ((i - a) + a = i)`]);;
219 let PASTECART_EQ = prove
220 (`!x y. (x = y) <=> (fstcart x = fstcart y) /\ (sndcart x = sndcart y)`,
221 MESON_TAC[PASTECART_FST_SND]);;
223 let FORALL_PASTECART = prove
224 (`(!p. P p) <=> !x y. P (pastecart x y)`,
225 MESON_TAC[PASTECART_FST_SND; FSTCART_PASTECART; SNDCART_PASTECART]);;
227 let EXISTS_PASTECART = prove
228 (`(?p. P p) <=> ?x y. P (pastecart x y)`,
229 MESON_TAC[PASTECART_FST_SND; FSTCART_PASTECART; SNDCART_PASTECART]);;
231 let PASTECART_INJ = prove
232 (`!x:real^M y:real^N w z. pastecart x y = pastecart w z <=> x = w /\ y = z`,
233 REWRITE_TAC[PASTECART_EQ; FSTCART_PASTECART; SNDCART_PASTECART]);;
235 (* ------------------------------------------------------------------------- *)
236 (* Automatically define a type of size n. *)
237 (* ------------------------------------------------------------------------- *)
239 let define_finite_type =
240 let lemma_pre = prove
241 (`~(n = 0) ==> ?x. x IN 1..n`,
242 DISCH_TAC THEN EXISTS_TAC `1` THEN REWRITE_TAC[IN_NUMSEG] THEN
243 POP_ASSUM MP_TAC THEN ARITH_TAC)
244 and lemma_post = prove
245 (`(!a:A. mk(dest a) = a) /\ (!r. r IN 1..n <=> dest(mk r) = r)
246 ==> (:A) HAS_SIZE n`,
247 REPEAT STRIP_TAC THEN
248 SUBGOAL_THEN `(:A) = IMAGE mk (1..n)` SUBST1_TAC THENL
249 [REWRITE_TAC[EXTENSION; IN_IMAGE; IN_UNIV];
250 MATCH_MP_TAC HAS_SIZE_IMAGE_INJ] THEN
251 ASM_MESON_TAC[HAS_SIZE_NUMSEG_1]) in
252 let POST_RULE = MATCH_MP lemma_post and n_tm = `n:num` in
254 let ns = string_of_int n in
255 let ns' = "auto_define_finite_type_"^ns in
256 let th0 = INST [mk_small_numeral n,n_tm] lemma_pre in
257 let th1 = MP th0 (EQF_ELIM(NUM_EQ_CONV(rand(lhand(concl th0))))) in
258 POST_RULE(new_type_definition ns ("mk_"^ns',"dest_"^ns') th1);;
260 (* ------------------------------------------------------------------------- *)
261 (* Predefine the cases 2, 3 and 4, which are especially useful for real^N. *)
262 (* ------------------------------------------------------------------------- *)
264 let HAS_SIZE_1 = prove
266 SUBGOAL_THEN `(:1) = {one}` SUBST1_TAC THENL
267 [REWRITE_TAC[EXTENSION; IN_UNIV; IN_SING] THEN MESON_TAC[one];
268 SIMP_TAC[NOT_IN_EMPTY; HAS_SIZE; FINITE_RULES; CARD_CLAUSES; ARITH]]);;
270 let HAS_SIZE_2 = define_finite_type 2;;
272 let HAS_SIZE_3 = define_finite_type 3;;
274 let HAS_SIZE_4 = define_finite_type 4;;
276 let DIMINDEX_1 = MATCH_MP DIMINDEX_UNIQUE HAS_SIZE_1;;
277 let DIMINDEX_2 = MATCH_MP DIMINDEX_UNIQUE HAS_SIZE_2;;
278 let DIMINDEX_3 = MATCH_MP DIMINDEX_UNIQUE HAS_SIZE_3;;
279 let DIMINDEX_4 = MATCH_MP DIMINDEX_UNIQUE HAS_SIZE_4;;
281 (* ------------------------------------------------------------------------- *)
282 (* Finiteness lemma. *)
283 (* ------------------------------------------------------------------------- *)
285 let FINITE_CART = prove
286 (`!P. (!i. 1 <= i /\ i <= dimindex(:N) ==> FINITE {x | P i x})
287 ==> FINITE {v:A^N | !i. 1 <= i /\ i <= dimindex(:N) ==> P i (v$i)}`,
288 GEN_TAC THEN DISCH_TAC THEN
290 `!n. n <= dimindex(:N)
291 ==> FINITE {v:A^N | (!i. 1 <= i /\ i <= dimindex(:N) /\ i <= n
293 (!i. 1 <= i /\ i <= dimindex(:N) /\ n < i
295 (MP_TAC o SPEC `dimindex(:N)`) THEN REWRITE_TAC[LE_REFL; LET_ANTISYM] THEN
297 [REWRITE_TAC[ARITH_RULE `1 <= i /\ i <= n /\ i <= 0 <=> F`] THEN
298 SIMP_TAC[ARITH_RULE `1 <= i /\ i <= n /\ 0 < i <=> 1 <= i /\ i <= n`] THEN
300 `{v | !i. 1 <= i /\ i <= dimindex (:N) ==> v$i = (@x. F)} =
301 {(lambda i. @x. F):A^N}`
302 (fun th -> SIMP_TAC[FINITE_RULES;th]) THEN
303 SIMP_TAC[EXTENSION; IN_SING; IN_ELIM_THM; CART_EQ; LAMBDA_BETA];
306 MATCH_MP_TAC FINITE_SUBSET THEN EXISTS_TAC
307 `IMAGE (\(x:A,v:A^N). (lambda i. if i = SUC n then x else v$i):A^N)
308 {x,v | x IN {x:A | P (SUC n) x} /\
309 v IN {v:A^N | (!i. 1 <= i /\ i <= dimindex(:N) /\ i <= n
311 (!i. 1 <= i /\ i <= dimindex (:N) /\ n < i
312 ==> v$i = (@x. F))}}` THEN
314 [MATCH_MP_TAC FINITE_IMAGE THEN
315 ASM_SIMP_TAC[FINITE_PRODUCT; ARITH_RULE `1 <= SUC n`;
316 ARITH_RULE `SUC n <= m ==> n <= m`];
318 REWRITE_TAC[SUBSET; IN_IMAGE; IN_ELIM_PAIR_THM; EXISTS_PAIR_THM] THEN
319 X_GEN_TAC `v:A^N` THEN REWRITE_TAC[IN_ELIM_THM] THEN
320 STRIP_TAC THEN EXISTS_TAC `(v:A^N)$(SUC n)` THEN
321 EXISTS_TAC `(lambda i. if i = SUC n then @x. F else (v:A^N)$i):A^N` THEN
322 SIMP_TAC[CART_EQ; LAMBDA_BETA; ARITH_RULE `i <= n ==> ~(i = SUC n)`] THEN
323 ASM_MESON_TAC[LE; ARITH_RULE `1 <= SUC n`;
324 ARITH_RULE `n < i /\ ~(i = SUC n) ==> SUC n < i`]);;
326 (* ------------------------------------------------------------------------- *)
327 (* More cardinality results for whole universe. *)
328 (* ------------------------------------------------------------------------- *)
330 let HAS_SIZE_CART_UNIV = prove
331 (`!m. (:A) HAS_SIZE m ==> (:A^N) HAS_SIZE m EXP (dimindex(:N))`,
332 REPEAT STRIP_TAC THEN
334 `(:(N)finite_image->A) HAS_SIZE m EXP (dimindex(:N))`
336 [ASM_SIMP_TAC[HAS_SIZE_FUNSPACE_UNIV; HAS_SIZE_FINITE_IMAGE];
337 DISCH_THEN(MP_TAC o ISPEC `mk_cart:((N)finite_image->A)->A^N` o
338 MATCH_MP (REWRITE_RULE[IMP_CONJ_ALT] HAS_SIZE_IMAGE_INJ)) THEN
339 REWRITE_TAC[IN_UNIV] THEN
340 ANTS_TAC THENL [MESON_TAC[cart_tybij]; MATCH_MP_TAC EQ_IMP] THEN
341 AP_THM_TAC THEN AP_TERM_TAC THEN MATCH_MP_TAC SURJECTIVE_IMAGE_EQ THEN
342 REWRITE_TAC[IN_UNIV] THEN MESON_TAC[cart_tybij]]);;
344 let CARD_CART_UNIV = prove
345 (`FINITE(:A) ==> CARD(:A^N) = CARD(:A) EXP dimindex(:N)`,
346 MESON_TAC[HAS_SIZE_CART_UNIV; HAS_SIZE]);;
348 let FINITE_CART_UNIV = prove
349 (`FINITE(:A) ==> FINITE(:A^N)`,
350 MESON_TAC[HAS_SIZE_CART_UNIV; HAS_SIZE]);;
352 (* ------------------------------------------------------------------------- *)
353 (* Explicit construction of a vector from a list of components. *)
354 (* ------------------------------------------------------------------------- *)
356 let vector = new_definition
357 `(vector l):A^N = lambda i. EL (i - 1) l`;;
359 (* ------------------------------------------------------------------------- *)
360 (* Convenient set membership elimination theorem. *)
361 (* ------------------------------------------------------------------------- *)
363 let IN_ELIM_PASTECART_THM = prove
364 (`!P a b. pastecart a b IN {pastecart x y | P x y} <=> P a b`,
365 REWRITE_TAC[IN_ELIM_THM; PASTECART_EQ;
366 FSTCART_PASTECART; SNDCART_PASTECART] THEN
369 (* ------------------------------------------------------------------------- *)
370 (* Variant of product types using pasting of vectors. *)
371 (* ------------------------------------------------------------------------- *)
373 parse_as_infix("PCROSS",(22,"right"));;
375 let PCROSS = new_definition
376 `s PCROSS t = {pastecart (x:A^M) (y:A^N) | x IN s /\ y IN t}`;;
378 let FORALL_IN_PCROSS = prove
379 (`(!z. z IN s PCROSS t ==> P z) <=>
380 (!x y. x IN s /\ y IN t ==> P(pastecart x y))`,
381 REWRITE_TAC[PCROSS; FORALL_IN_GSPEC]);;
383 let EXISTS_IN_PCROSS = prove
384 (`(?z. z IN s PCROSS t /\ P z) <=>
385 (?x y. x IN s /\ y IN t /\ P(pastecart x y))`,
386 REWRITE_TAC[PCROSS; EXISTS_IN_GSPEC; CONJ_ASSOC]);;
388 let PASTECART_IN_PCROSS = prove
389 (`!s t x y. (pastecart x y) IN (s PCROSS t) <=> x IN s /\ y IN t`,
390 REWRITE_TAC[PCROSS; IN_ELIM_PASTECART_THM]);;
392 let PCROSS_EQ_EMPTY = prove
393 (`!s t. s PCROSS t = {} <=> s = {} \/ t = {}`,
394 REWRITE_TAC[PCROSS] THEN SET_TAC[]);;
396 let PCROSS_EMPTY = prove
397 (`(!s. s PCROSS {} = {}) /\ (!t. {} PCROSS t = {})`,
398 REWRITE_TAC[PCROSS_EQ_EMPTY]);;
400 let SUBSET_PCROSS = prove
401 (`!s t s' t'. s PCROSS t SUBSET s' PCROSS t' <=>
402 s = {} \/ t = {} \/ s SUBSET s' /\ t SUBSET t'`,
403 SIMP_TAC[PCROSS; EXTENSION; IN_ELIM_PASTECART_THM; SUBSET;
404 FORALL_PASTECART; PASTECART_IN_PCROSS; NOT_IN_EMPTY] THEN MESON_TAC[]);;
406 let PCROSS_MONO = prove
407 (`!s t s' t'. s SUBSET s' /\ t SUBSET t' ==> s PCROSS t SUBSET s' PCROSS t'`,
408 SIMP_TAC[SUBSET_PCROSS]);;
410 let PCROSS_EQ = prove
411 (`!s s':real^M->bool t t':real^N->bool.
412 s PCROSS t = s' PCROSS t' <=>
413 (s = {} \/ t = {}) /\ (s' = {} \/ t' = {}) \/ s = s' /\ t = t'`,
414 REWRITE_TAC[GSYM SUBSET_ANTISYM_EQ; SUBSET_PCROSS] THEN SET_TAC[]);;
416 let UNIV_PCROSS_UNIV = prove
417 (`(:A^M) PCROSS (:A^N) = (:A^(M,N)finite_sum)`,
418 REWRITE_TAC[EXTENSION; FORALL_PASTECART; PASTECART_IN_PCROSS; IN_UNIV]);;
420 let HAS_SIZE_PCROSS = prove
421 (`!(s:A^M->bool) (t:A^N->bool) m n.
422 s HAS_SIZE m /\ t HAS_SIZE n ==> (s PCROSS t) HAS_SIZE (m * n)`,
423 REPEAT GEN_TAC THEN DISCH_TAC THEN
424 FIRST_ASSUM(MP_TAC o MATCH_MP HAS_SIZE_PRODUCT) THEN
425 MATCH_MP_TAC EQ_IMP THEN SPEC_TAC(`m * n:num`,`k:num`) THEN
426 MATCH_MP_TAC BIJECTIONS_HAS_SIZE_EQ THEN
427 EXISTS_TAC `\(x:A^M,y:A^N). pastecart x y` THEN
428 EXISTS_TAC `\z:A^(M,N)finite_sum. fstcart z,sndcart z` THEN
429 REWRITE_TAC[FORALL_IN_GSPEC; PASTECART_IN_PCROSS] THEN
430 REWRITE_TAC[IN_ELIM_PAIR_THM; PASTECART_FST_SND] THEN
431 REWRITE_TAC[FORALL_IN_PCROSS; FSTCART_PASTECART; SNDCART_PASTECART]);;
433 let FINITE_PCROSS = prove
434 (`!(s:A^M->bool) (t:A^N->bool).
435 FINITE s /\ FINITE t ==> FINITE(s PCROSS t)`,
436 MESON_TAC[REWRITE_RULE[HAS_SIZE] HAS_SIZE_PCROSS]);;
438 let FINITE_PCROSS_EQ = prove
439 (`!(s:A^M->bool) (t:A^N->bool).
440 FINITE(s PCROSS t) <=> s = {} \/ t = {} \/ FINITE s /\ FINITE t`,
442 MAP_EVERY ASM_CASES_TAC [`s:A^M->bool = {}`; `t:A^N->bool = {}`] THEN
443 ASM_REWRITE_TAC[PCROSS_EMPTY; FINITE_EMPTY] THEN
444 EQ_TAC THEN SIMP_TAC[FINITE_PCROSS] THEN REPEAT STRIP_TAC THEN
445 MATCH_MP_TAC FINITE_SUBSET THENL
446 [EXISTS_TAC `IMAGE fstcart ((s PCROSS t):A^(M,N)finite_sum->bool)`;
447 EXISTS_TAC `IMAGE sndcart ((s PCROSS t):A^(M,N)finite_sum->bool)`] THEN
448 ASM_SIMP_TAC[FINITE_IMAGE; SUBSET; IN_IMAGE; EXISTS_PASTECART] THEN
449 REWRITE_TAC[PASTECART_IN_PCROSS; FSTCART_PASTECART; SNDCART_PASTECART] THEN
452 let IMAGE_FSTCART_PCROSS = prove
453 (`!s:real^M->bool t:real^N->bool.
454 IMAGE fstcart (s PCROSS t) = if t = {} then {} else s`,
455 REPEAT GEN_TAC THEN COND_CASES_TAC THEN
456 ASM_REWRITE_TAC[PCROSS_EMPTY; IMAGE_CLAUSES] THEN
457 REWRITE_TAC[EXTENSION; IN_IMAGE] THEN ONCE_REWRITE_TAC[CONJ_SYM] THEN
458 REWRITE_TAC[EXISTS_IN_PCROSS; FSTCART_PASTECART] THEN ASM SET_TAC[]);;
460 let IMAGE_SNDCART_PCROSS = prove
461 (`!s:real^M->bool t:real^N->bool.
462 IMAGE sndcart (s PCROSS t) = if s = {} then {} else t`,
463 REPEAT GEN_TAC THEN COND_CASES_TAC THEN
464 ASM_REWRITE_TAC[PCROSS_EMPTY; IMAGE_CLAUSES] THEN
465 REWRITE_TAC[EXTENSION; IN_IMAGE] THEN ONCE_REWRITE_TAC[CONJ_SYM] THEN
466 REWRITE_TAC[EXISTS_IN_PCROSS; SNDCART_PASTECART] THEN ASM SET_TAC[]);;
468 let PCROSS_INTER = prove
469 (`(!s t u. s PCROSS (t INTER u) = (s PCROSS t) INTER (s PCROSS u)) /\
470 (!s t u. (s INTER t) PCROSS u = (s PCROSS u) INTER (t PCROSS u))`,
471 REWRITE_TAC[EXTENSION; FORALL_PASTECART; IN_INTER; PASTECART_IN_PCROSS] THEN
472 REPEAT STRIP_TAC THEN CONV_TAC TAUT);;
474 let PCROSS_UNION = prove
475 (`(!s t u. s PCROSS (t UNION u) = (s PCROSS t) UNION (s PCROSS u)) /\
476 (!s t u. (s UNION t) PCROSS u = (s PCROSS u) UNION (t PCROSS u))`,
477 REWRITE_TAC[EXTENSION; FORALL_PASTECART; IN_UNION; PASTECART_IN_PCROSS] THEN
478 REPEAT STRIP_TAC THEN CONV_TAC TAUT);;
480 let PCROSS_DIFF = prove
481 (`(!s t u. s PCROSS (t DIFF u) = (s PCROSS t) DIFF (s PCROSS u)) /\
482 (!s t u. (s DIFF t) PCROSS u = (s PCROSS u) DIFF (t PCROSS u))`,
483 REWRITE_TAC[EXTENSION; FORALL_PASTECART; IN_DIFF; PASTECART_IN_PCROSS] THEN
484 REPEAT STRIP_TAC THEN CONV_TAC TAUT);;
486 let INTER_PCROSS = prove
488 (s PCROSS t) INTER (s' PCROSS t') = (s INTER s') PCROSS (t INTER t')`,
489 REWRITE_TAC[EXTENSION; IN_INTER; FORALL_PASTECART; PASTECART_IN_PCROSS] THEN
492 let PCROSS_UNIONS_UNIONS,PCROSS_UNIONS = (CONJ_PAIR o prove)
493 (`(!f g. (UNIONS f) PCROSS (UNIONS g) =
494 UNIONS {s PCROSS t | s IN f /\ t IN g}) /\
495 (!s f. s PCROSS (UNIONS f) = UNIONS {s PCROSS t | t IN f}) /\
496 (!f t. (UNIONS f) PCROSS t = UNIONS {s PCROSS t | s IN f})`,
497 REWRITE_TAC[UNIONS_GSPEC; EXTENSION; FORALL_PASTECART; IN_ELIM_THM;
498 PASTECART_IN_PCROSS] THEN