1 (* ========================================================================== *)
2 (* FLYSPECK - BOOK FORMALIZATION *)
5 (* Copied from HOL Light jordan directory *)
6 (* Author: Thomas C. Hales *)
8 (* ========================================================================== *)
11 The file in the HOL Light distribution is longer, with results about
12 Euclidan space that are not relevant here.
14 May 7, 2011, renamed INV -> INVERSE to avoid clash with HOL Library/rstc.ml
17 module Misc_defs_and_lemmas = struct
21 open Parse_ext_override_interface;;
22 (* open Refinement;; *)
26 (* labels_flag:= true;; *)
28 let prove_by_refinement = Refinement.enhanced_prove_by_refinement true ALL_TAC;;
30 let LABEL_ALL_TAC = Refinement.LABEL_ALL_TAC;;
32 unambiguous_interface();;
35 let dirac_delta = new_definition `dirac_delta i =
36 \j. if (i=j) then &1 else &0`;;
39 let dirac_delta = new_definition `dirac_delta (i:num) j =
40 if (i=j) then &. 1 else &. 0`;;
44 let dirac_delta = prove_by_refinement(`!i. dirac_delta i =
45 (\j. if (i=j) then &. 1 else &. 0)`,
48 ONCE_REWRITE_TAC[FUN_EQ_THM];
49 REWRITE_TAC[dirac_delta_thm];
54 let min_num = new_definition
55 `min_num (X:num->bool) = @m. (m IN X) /\ (!n. (n IN X) ==> (m <= n))`;;
57 let min_least = prove_by_refinement (
58 `!(X:num->bool) c. (X c) ==> (X (min_num X) /\ (min_num X <=| c))`,
62 REWRITE_TAC[min_num;IN];
65 SUBGOAL_THEN `?n. (X:num->bool) n /\ (!m. m <| n ==> ~X m)` MP_TAC;
66 REWRITE_TAC[(GSYM (ISPEC `X:num->bool` num_WOP))];
68 DISCH_THEN CHOOSE_TAC;
69 ASSUME_TAC (select_thm `\m. (X:num->bool) m /\ (!n. X n ==> m <=| n)` `n:num`);
70 ABBREV_TAC `r = @m. (X:num->bool) m /\ (!n. X n ==> m <=| n)`;
71 ASM_MESON_TAC[ ARITH_RULE `~(n' < n) ==> (n <=| n') `]
76 let max_real = new_definition(`max_real x y =
77 if (y <. x) then x else y`);;
79 let min_real = new_definition(`min_real x y =
80 if (x <. y) then x else y`);;
82 (* let deriv = new_definition(`deriv f x = @d. (f diffl d)(x)`);;
83 let deriv2 = new_definition(`deriv2 f = (deriv (deriv f))`);; *)
85 let square_le = prove_by_refinement(
86 `!x y. (&.0 <=. x) /\ (&.0 <=. y) /\ (x*.x <=. y*.y) ==> (x <=. y)`,
91 UNDISCH_FIND_TAC `( *. )` ;
92 ONCE_REWRITE_TAC[REAL_ARITH `(a <=. b) <=> (&.0 <= (b - a))`];
93 REWRITE_TAC[GSYM REAL_DIFFSQ];
95 DISJ_CASES_TAC (REAL_ARITH `&.0 < (y+x) \/ (y+x <=. (&.0))`);
96 MATCH_MP_TAC (SPEC `(y+x):real` REAL_LE_LCANCEL_IMP);
97 ASM_REWRITE_TAC [REAL_ARITH `x * (&.0) = (&.0)`];
98 CLEAN_ASSUME_TAC (REAL_ARITH `(&.0 <= y) /\ (&.0 <=. x) /\ (y+x <= (&.0)) ==> ((x= &.0) /\ (y= &.0))`);
99 ASM_REWRITE_TAC[REAL_ARITH `&.0 <=. (&.0 -. (&.0))`];
104 let max_num_sequence = prove_by_refinement(
105 `!(t:num->num). (?n. !m. (n <=| m) ==> (t m = 0)) ==>
106 (?M. !i. (t i <=| M))`,
110 REWRITE_TAC[GSYM LEFT_FORALL_IMP_THM];
112 SPEC_TAC (`t:num->num`,`t:num->num`);
113 SPEC_TAC (`n:num`,`n:num`);
116 REWRITE_TAC[ARITH_RULE `0<=|m`];
119 ASM_MESON_TAC[ARITH_RULE`(a=0) ==> (a <=|0)`];
121 ABBREV_TAC `b = \m. (if (m=n) then 0 else (t (m:num)) )`;
122 FIRST_ASSUM (fun t-> ASSUME_TAC (SPEC `b:num->num` t));
123 SUBGOAL_MP_TAC `((b:num->num) (n) = 0) /\ (!m. ~(m=n) ==> (b m = t m))`;
134 FIRST_ASSUM (fun t-> MP_TAC(SPEC `b:num->num` t));
135 SUBGOAL_MP_TAC `!m. (n<=|m) ==> (b m =0)`;
137 ASM_CASES_TAC `m = (n:num)`;
139 SUBGOAL_MP_TAC ( `(n <=| m) /\ (~(m = n)) ==> (SUC n <=| m)`);
143 ASM_MESON_TAC[]; (* good *)
144 DISCH_THEN (fun t-> REWRITE_TAC[t]);
145 DISCH_THEN CHOOSE_TAC;
146 EXISTS_TAC `(M:num) + (t:num->num) n`;
148 ASM_CASES_TAC `(i:num) = n`;
151 MATCH_MP_TAC (ARITH_RULE `x <=| M ==> (x <=| M+ u)`);
156 let REAL_INV_LT = prove_by_refinement(
157 `!x y z. (&.0 <. x) ==> ((inv(x)*y < z) <=> (y <. x*z))`,
162 REWRITE_TAC[REAL_ARITH `inv x * y = y* inv x`];
163 REWRITE_TAC[GSYM real_div];
164 ASM_SIMP_TAC[REAL_LT_LDIV_EQ];
169 let REAL_MUL_NN = prove_by_refinement(
170 `!x y. (&.0 <= x*y) <=>
171 ((&.0 <= x /\ (&.0 <=. y)) \/ ((x <= &.0) /\ (y <= &.0) ))`,
175 SUBGOAL_MP_TAC `! x y. ((&.0 < x) ==> ((&.0 <= x*y) <=> ((&.0 <= x /\ (&.0 <=. y)) \/ ((x <= &.0) /\ (y <= &.0) ))))`;
177 ASM_SIMP_TAC[REAL_ARITH `((&.0 <. x) ==> (&.0 <=. x))`;REAL_ARITH `(&.0 <. x) ==> ~(x <=. &.0)`];
179 ASM_MESON_TAC[REAL_PROP_NN_LCANCEL];
180 ASM_MESON_TAC[REAL_LE_MUL;REAL_LT_IMP_LE];
182 DISJ_CASES_TAC (REAL_ARITH `(&.0 < x) \/ (x = &.0) \/ (x < &.0)`);
184 UND 1 THEN DISCH_THEN DISJ_CASES_TAC;
187 ASM_SIMP_TAC[REAL_ARITH `((x <. &.0) ==> ~(&.0 <=. x))`;REAL_ARITH `(x <. &.0) ==> (x <=. &.0)`];
188 USE 0 (SPECL [`--. (x:real)`;`--. (y:real)`]);
192 ASM_SIMP_TAC[REAL_ARITH `((x <. &.0) ==> ~(&.0 <=. x))`;REAL_ARITH `(x <. &.0) ==> (x <=. &.0)`];
196 let ABS_SQUARE = prove_by_refinement(
197 `!t u. abs(t) <. u ==> t*t <. u*u`,
202 CONV_TAC (SUBS_CONV[SPEC `t:real` (REWRITE_RULE[POW_2] (GSYM REAL_POW2_ABS))]);
203 ASSUME_TAC REAL_ABS_POS;
204 USE 0 (SPEC `t:real`);
205 ABBREV_TAC `(b:real) = (abs t)`;
208 MATCH_MP_TAC REAL_PROP_LT_LRMUL;
214 let ABS_SQUARE_LE = prove_by_refinement(
215 `!t u. abs(t) <=. u ==> t*t <=. u*u`,
220 CONV_TAC (SUBS_CONV[SPEC `t:real` (REWRITE_RULE[POW_2] (GSYM REAL_POW2_ABS))]);
221 ASSUME_TAC REAL_ABS_POS;
222 USE 0 (SPEC `t:real`);
223 ABBREV_TAC `(b:real) = (abs t)`;
226 MATCH_MP_TAC REAL_PROP_LE_LRMUL;
232 let POW_2_LE1 = REAL_LE_POW2;;
234 let REAL_ADD = REAL_OF_NUM_ADD;;
236 let POW_2_LT = prove_by_refinement(
240 REWRITE_TAC[pow; REAL_LT_01] ;
241 REWRITE_TAC[pow;ADD1; GSYM REAL_ADD; GSYM REAL_DOUBLE];
242 MATCH_MP_TAC REAL_LTE_ADD2;
243 ASM_REWRITE_TAC[POW_2_LE1];
247 let twopow_eps = prove_by_refinement(
248 `!R e. ?n. (&.0 <. R)/\ (&.0 <. e) ==> R*(twopow(--: (&:n))) <. e`,
253 REWRITE_TAC[TWOPOW_NEG]; (* cs6b *)
254 ASSUME_TAC (prove(`!n. &.0 < &.2 pow n`,REDUCE_TAC THEN ARITH_TAC));
255 ONCE_REWRITE_TAC[REAL_MUL_AC];
256 ASM_SIMP_TAC[REAL_INV_LT];
257 ASM_SIMP_TAC[GSYM REAL_LT_LDIV_EQ];
258 CONV_TAC (quant_right_CONV "n");
260 ASSUME_TAC (SPEC `R/e` REAL_ARCH_SIMPLE);
264 MESON_TAC[POW_2_LT;REAL_LET_TRANS];
270 (* ------------------------------------------------------------------ *)
271 (* finite products, in imitation of finite sums *)
272 (* ------------------------------------------------------------------ *)
274 let prod_EXISTS = prove_by_refinement(
275 `?prod. (!f n. prod(n,0) f = &1) /\
276 (!f m n. prod(n,SUC m) f = prod(n,m) f * f(n + m))`,
279 (CHOOSE_TAC o prove_recursive_functions_exist num_RECURSION) `(!f n. sm n 0 f = &1) /\ (!f m n. sm n (SUC m) f = sm n m f * f(n + m))` ;
280 EXISTS_TAC `\(n,m) f. (sm:num->num->(num->real)->real) n m f`;
281 CONV_TAC(DEPTH_CONV GEN_BETA_CONV) THEN ASM_REWRITE_TAC[]
285 let prod_DEF = new_specification ["prod"] prod_EXISTS;;
288 (`!n m. (prod(n,0) f = &1) /\
289 (prod(n,SUC m) f = prod(n,m) f * f(n + m))`,
291 REWRITE_TAC[prod_DEF]);;
294 let PROD_TWO = prove_by_refinement(
295 `!f n p. prod(0,n) f * prod(n,p) f = prod(0,n + p) f`,
298 GEN_TAC THEN GEN_TAC THEN INDUCT_TAC THEN REWRITE_TAC[prod; REAL_MUL_RID; MULT_CLAUSES;ADD_0];
299 REWRITE_TAC[ARITH_RULE `n+| (SUC p) = (SUC (n+|p))`;prod;ARITH_RULE `0+|n = n`];
300 ASM_REWRITE_TAC[REAL_MUL_ASSOC];
305 let ABS_PROD = prove_by_refinement(
306 `!f m n. abs(prod(m,n) f) = prod(m,n) (\n. abs(f n))`,
309 GEN_TAC THEN GEN_TAC THEN INDUCT_TAC;
312 ASM_REWRITE_TAC[prod;ABS_MUL]
316 let PROD_EQ = prove_by_refinement
317 (`!f g m n. (!r. m <= r /\ r < (n + m) ==> (f(r) = g(r)))
318 ==> (prod(m,n) f = prod(m,n) g)`,
322 GEN_TAC THEN GEN_TAC THEN GEN_TAC THEN INDUCT_TAC THEN REWRITE_TAC[prod];
324 DISCH_THEN (fun th -> MP_TAC th THEN (MP_TAC (SPEC `m+|n` th)));
325 REWRITE_TAC[ARITH_RULE `(m<=| (m+|n))/\ (m +| n <| (SUC n +| m))`];
328 AP_THM_TAC THEN AP_TERM_TAC;
329 FIRST_X_ASSUM MATCH_MP_TAC;
330 GEN_TAC THEN DISCH_TAC;
331 FIRST_X_ASSUM MATCH_MP_TAC;
332 ASM_MESON_TAC[ARITH_RULE `r <| (n+| m) ==> (r <| (SUC n +| m))`]
337 let PROD_POS = prove_by_refinement
338 (`!f. (!n. &0 <= f(n)) ==> !m n. &0 <= prod(m,n) f`,
342 GEN_TAC THEN DISCH_TAC THEN GEN_TAC THEN INDUCT_TAC THEN REWRITE_TAC[prod];
344 ASM_MESON_TAC[REAL_LE_MUL]
348 let PROD_POS_GEN = prove_by_refinement
350 (!n. m <= n ==> &0 <= f(n))
351 ==> &0 <= prod(m,n) f`,
355 REPEAT STRIP_TAC THEN SPEC_TAC(`n:num`,`n:num`) THEN INDUCT_TAC THEN REWRITE_TAC[prod];
357 ASM_MESON_TAC[REAL_LE_MUL;ARITH_RULE `m <=| (m +| n)`]
363 (`!f m n. abs(prod(m,n) (\m. abs(f m))) = prod(m,n) (\m. abs(f m))`,
365 REWRITE_TAC[ABS_PROD;REAL_ARITH `||. (||. x) = (||. x)`]);;
368 let PROD_ZERO = prove_by_refinement
369 (`!f m n. (?p. (m <= p /\ (p < (n+| m)) /\ (f p = (&.0)))) ==>
373 GEN_TAC THEN GEN_TAC THEN INDUCT_TAC THEN (REWRITE_TAC[prod]);
375 DISCH_THEN CHOOSE_TAC;
376 ASM_CASES_TAC `p <| (n+| m)`;
377 MATCH_MP_TAC (prove (`(x = (&.0)) ==> (x *. y = (&.0))`,(DISCH_THEN (fun th -> (REWRITE_TAC[th]))) THEN REAL_ARITH_TAC));
378 FIRST_X_ASSUM MATCH_MP_TAC;
380 POP_ASSUM (fun th -> ASSUME_TAC (MATCH_MP (ARITH_RULE `(~(p <| (n+|m)) ==> ((p <| ((SUC n) +| m)) ==> (p = ((m +| n)))))`) th));
381 MATCH_MP_TAC (prove (`(x = (&.0)) ==> (y *. x = (&.0))`,(DISCH_THEN (fun th -> (REWRITE_TAC[th]))) THEN REAL_ARITH_TAC));
386 let PROD_MUL = prove_by_refinement(
387 `!f g m n. prod(m,n) (\n. f(n) * g(n)) = prod(m,n) f * prod(m,n) g`,
390 EVERY(replicate GEN_TAC 3) THEN INDUCT_TAC THEN ASM_REWRITE_TAC[prod];
392 REWRITE_TAC[REAL_MUL_AC];
396 let PROD_CMUL = prove_by_refinement(
397 `!f c m n. prod(m,n) (\n. c * f(n)) = (c **. n) * prod(m,n) f`,
400 EVERY(replicate GEN_TAC 3) THEN INDUCT_TAC THEN ASM_REWRITE_TAC[prod;pow];
402 REWRITE_TAC[REAL_MUL_AC];
406 (* ------------------------------------------------------------------ *)
407 (* LEMMAS ABOUT SETS *)
408 (* ------------------------------------------------------------------ *)
410 (* IN_ELIM_THM produces garbled results at times. I like this better: *)
412 (*** JRH replaced this with the "new" IN_ELIM_THM; see how it works.
414 let IN_ELIM_THM' = prove_by_refinement(
415 `(!P. !x:A. x IN (GSPEC P) <=> P x) /\
416 (!P. !x:A. x IN (\x. P x) <=> P x) /\
417 (!P. !x:A. (GSPEC P) x <=> P x) /\
418 (!P (x:A) (t:A). (\t. (?y:A. P y /\ (t = y))) x <=> P x)`,
421 REWRITE_TAC[IN; GSPEC];
428 let IN_ELIM_THM' = IN_ELIM_THM;;
430 let SURJ_IMAGE = prove_by_refinement(
431 `!(f:A->B) a b. SURJ f a b ==> (b = (IMAGE f a))`,
436 REWRITE_TAC[SURJ;IMAGE];
438 REWRITE_TAC[EXTENSION];
440 REWRITE_TAC[IN_ELIM_THM];
447 let SURJ_FINITE = prove_by_refinement(
448 `!a b (f:A->B). FINITE a /\ (SURJ f a b) ==> FINITE b`,
452 ASM_MESON_TAC[SURJ_IMAGE;FINITE_IMAGE]
457 let BIJ_INVERSE = prove_by_refinement(
458 `!a b (f:A->B). (SURJ f a b) ==> (?(g:B->A). (INJ g b a))`,
464 SUBGOAL_THEN `!y. ?u. ((y IN b) ==> ((u IN a) /\ ((f:A->B) u = y)))` ASSUME_TAC;
467 H_REWRITE_RULE[THM SKOLEM_THM] (HYP "1");
469 H_UNDISCH_TAC (HYP"2");
470 DISCH_THEN CHOOSE_TAC;
472 REWRITE_TAC[INJ] THEN CONJ_TAC THEN (ASM_MESON_TAC[])
478 (* complement of an intersection is a union of complements *)
479 let UNIONS_INTERS = prove_by_refinement(
481 (X DIFF (INTERS V) = UNIONS (IMAGE ((DIFF) X) V))`,
486 MATCH_MP_TAC SUBSET_ANTISYM;
488 REWRITE_TAC[SUBSET;IMAGE;IN_ELIM_THM];
490 REWRITE_TAC[IN_DIFF;IN_INTERS;IN_UNIONS;NOT_FORALL_THM];
492 UNDISCH_FIND_THEN `(?)` CHOOSE_TAC;
493 EXISTS_TAC `(X DIFF t):A->bool`;
494 REWRITE_TAC[IN_ELIM_THM];
496 EXISTS_TAC `t:A->bool`;
498 REWRITE_TAC[IN_DIFF];
500 REWRITE_TAC[SUBSET;IMAGE;IN_ELIM_THM];
502 REWRITE_TAC[IN_DIFF;IN_UNIONS];
503 DISCH_THEN CHOOSE_TAC;
504 UNDISCH_FIND_TAC `(IN)`;
505 REWRITE_TAC[IN_INTERS;IN_ELIM_THM];
507 UNDISCH_FIND_THEN `(?)` CHOOSE_TAC;
509 ASM_MESON_TAC[SUBSET_DIFF;SUBSET];
510 REWRITE_TAC[NOT_FORALL_THM];
511 EXISTS_TAC `x:A->bool`;
512 ASM_MESON_TAC[IN_DIFF];
517 let INTERS_SUBSET = prove_by_refinement (
518 `!X (A:A->bool). (A IN X) ==> (INTERS X SUBSET A)`,
522 REWRITE_TAC[SUBSET;IN_INTERS];
527 let sub_union = prove_by_refinement(
528 `!X (U:(A->bool)->bool). (U X) ==> (X SUBSET (UNIONS U))`,
532 REWRITE_TAC[SUBSET;IN_ELIM_THM;UNIONS];
535 EXISTS_TAC `X:A->bool`;
540 let IMAGE_SURJ = prove_by_refinement(
541 `!(f:A->B) a. SURJ f a (IMAGE f a)`,
544 REWRITE_TAC[SURJ;IMAGE;IN_ELIM_THM];
549 let SUBSET_PREIMAGE = prove_by_refinement(
550 `!(f:A->B) X Y. (Y SUBSET (IMAGE f X)) ==>
551 (?Z. (Z SUBSET X) /\ (Y = IMAGE f Z))`,
555 EXISTS_TAC `{x | (x IN (X:A->bool))/\ (f x IN (Y:B->bool)) }`;
557 REWRITE_TAC[SUBSET;IN_ELIM_THM];
559 REWRITE_TAC[EXTENSION];
561 UNDISCH_FIND_TAC `(SUBSET)`;
562 REWRITE_TAC[SUBSET;IN_IMAGE];
563 REWRITE_TAC[IN_ELIM_THM];
564 DISCH_THEN (fun t-> MP_TAC (SPEC `y:B` t));
569 let UNIONS_INTER = prove_by_refinement(
570 `!(U:(A->bool)->bool) A. (((UNIONS U) INTER A) =
571 (UNIONS (IMAGE ((INTER) A) U)))`,
575 MATCH_MP_TAC (prove(`((C SUBSET (B:A->bool)) /\ (C SUBSET A) /\ ((A INTER B) SUBSET C)) ==> ((B INTER A) = C)`,SET_TAC[]));
577 REWRITE_TAC[SUBSET;UNIONS;IN_ELIM_THM];
578 REWRITE_TAC[IN_IMAGE];
580 REWRITE_TAC[SUBSET;UNIONS;IN_IMAGE];
582 REWRITE_TAC[IN_ELIM_THM];
584 DISCH_THEN CHOOSE_TAC;
585 ASM_MESON_TAC[IN_INTER];
586 REWRITE_TAC[IN_INTER];
587 REWRITE_TAC[IN_ELIM_THM];
590 UNDISCH_FIND_THEN `(?)` CHOOSE_TAC;
591 EXISTS_TAC `A INTER (u:A->bool)`;
596 let UNIONS_SUBSET = prove_by_refinement(
597 `!U (X:A->bool). (!A. (A IN U) ==> (A SUBSET X)) ==> (UNIONS U SUBSET X)`,
605 let SUBSET_INTER = prove_by_refinement(
606 `!X A (B:A->bool). (X SUBSET (A INTER B)) <=> (X SUBSET A) /\ (X SUBSET B)`,
609 REWRITE_TAC[SUBSET;INTER;IN_ELIM_THM];
614 let EMPTY_EXISTS = prove_by_refinement(
615 `!X. ~(X = {}) <=> (? (u:A). (u IN X))`,
618 REWRITE_TAC[EXTENSION];
619 REWRITE_TAC[IN;EMPTY];
624 let UNIONS_UNIONS = prove_by_refinement(
625 `!A B. (A SUBSET B) ==>(UNIONS (A:(A->bool)->bool) SUBSET (UNIONS B))`,
628 REWRITE_TAC[SUBSET;UNIONS;IN_ELIM_THM];
634 (* nested union can flatten from outside in, or inside out *)
635 let UNIONS_IMAGE_UNIONS = prove_by_refinement(
636 `!(X:((A->bool)->bool)->bool).
637 UNIONS (UNIONS X) = (UNIONS (IMAGE UNIONS X))`,
641 REWRITE_TAC[EXTENSION;IN_UNIONS];
643 REWRITE_TAC[EXTENSION;IN_UNIONS];
645 DISCH_THEN (CHOOSE_THEN MP_TAC);
648 DISCH_THEN CHOOSE_TAC;
649 EXISTS_TAC `UNIONS (t':(A->bool)->bool)`;
650 REWRITE_TAC[IN_UNIONS;IN_IMAGE];
652 EXISTS_TAC `(t':(A->bool)->bool)`;
655 DISCH_THEN CHOOSE_TAC;
657 REWRITE_TAC[IN_IMAGE];
660 DISCH_THEN CHOOSE_TAC;
661 UNDISCH_TAC `(x:A) IN t`;
662 FIRST_ASSUM (fun t-> REWRITE_TAC[t]);
663 REWRITE_TAC[IN_UNIONS];
664 DISCH_THEN (CHOOSE_TAC);
665 EXISTS_TAC `t':(A->bool)`;
667 EXISTS_TAC `x':(A->bool)->bool`;
674 let INTERS_SUBSET2 = prove_by_refinement(
675 `!X A. (?(x:A->bool). (A x /\ (x SUBSET X))) ==> ((INTERS A) SUBSET X)`,
678 REWRITE_TAC[SUBSET;INTERS;IN_ELIM_THM'];
684 (**** New proof by JRH; old one breaks because of new set comprehensions
686 let INTERS_EMPTY = prove_by_refinement(
687 `INTERS EMPTY = (UNIV:A->bool)`,
690 REWRITE_TAC[INTERS;NOT_IN_EMPTY;IN_ELIM_THM';];
691 REWRITE_TAC[UNIV;GSPEC];
694 REWRITE_TAC[IN_ELIM_THM'];
701 let INTERS_EMPTY = prove_by_refinement(
702 `INTERS EMPTY = (UNIV:A->bool)`,
705 let preimage = new_definition `preimage dom (f:A->B)
706 Z = {x | (x IN dom) /\ (f x IN Z)}`;;
708 let in_preimage = prove_by_refinement(
709 `!f x Z dom. x IN (preimage dom (f:A->B) Z) <=> (x IN dom) /\ (f x IN Z)`,
712 REWRITE_TAC[preimage];
713 REWRITE_TAC[IN_ELIM_THM']
717 (* Partial functions, which we identify with functions that
718 take the canonical choice of element outside the domain. *)
720 let supp = new_definition
721 `supp (f:A->B) = \ x. ~(f x = (CHOICE (UNIV:B ->bool)) )`;;
723 let func = new_definition
724 `func a b = (\ (f:A->B). ((!x. (x IN a) ==> (f x IN b)) /\
725 ((supp f) SUBSET a))) `;;
729 let reflexive = new_definition
730 `reflexive (f:A->A->bool) <=> (!x. f x x)`;;
732 let symmetric = new_definition
733 `symmetric (f:A->A->bool) <=> (!x y. f x y ==> f y x)`;;
735 let transitive = new_definition
736 `transitive (f:A->A->bool) <=> (!x y z. f x y /\ f y z ==> f x z)`;;
738 let equivalence_relation = new_definition
739 `equivalence_relation (f:A->A->bool) <=>
740 (reflexive f) /\ (symmetric f) /\ (transitive f)`;;
742 (* We do not introduce the equivalence class of f explicitly, because
743 it is represented directly in HOL by (f a) *)
745 let partition_DEF = new_definition
746 `partition (A:A->bool) SA <=> (UNIONS SA = A) /\
747 (!a b. ((a IN SA) /\ (b IN SA) /\ (~(a = b)) ==> ({} = (a INTER b))))`;;
749 let DIFF_DIFF2 = prove_by_refinement(
750 `!X (A:A->bool). (A SUBSET X) ==> ((X DIFF (X DIFF A)) = A)`,
755 (*** Old proof replaced by JRH: no longer UNWIND_THM[12] clause in IN_ELIM_THM
757 let GSPEC_THM = prove_by_refinement(
758 `!P (x:A). (?y. P y /\ (x = y)) <=> P x`,
759 [REWRITE_TAC[IN_ELIM_THM]]);;
763 let GSPEC_THM = prove_by_refinement(
764 `!P (x:A). (?y. P y /\ (x = y)) <=> P x`,
767 let CARD_GE_REFL = prove
768 (`!s:A->bool. s >=_c s`,
769 GEN_TAC THEN REWRITE_TAC[GE_C] THEN
770 EXISTS_TAC `\x:A. x` THEN MESON_TAC[]);;
772 let FINITE_HAS_SIZE_LEMMA = prove
773 (`!s:A->bool. FINITE s ==> ?n:num. {x | x < n} >=_c s`,
774 MATCH_MP_TAC FINITE_INDUCT THEN CONJ_TAC THENL
775 [EXISTS_TAC `0` THEN REWRITE_TAC[NOT_IN_EMPTY; GE_C; IN_ELIM_THM];
776 REPEAT GEN_TAC THEN DISCH_THEN(X_CHOOSE_TAC `N:num`) THEN
777 EXISTS_TAC `SUC N` THEN POP_ASSUM MP_TAC THEN PURE_REWRITE_TAC[GE_C] THEN
778 DISCH_THEN(X_CHOOSE_TAC `f:num->A`) THEN
779 EXISTS_TAC `\n:num. if n = N then x:A else f n` THEN
780 X_GEN_TAC `y:A` THEN PURE_REWRITE_TAC[IN_INSERT] THEN
781 DISCH_THEN(DISJ_CASES_THEN2 SUBST_ALL_TAC (ANTE_RES_THEN MP_TAC)) THENL
782 [EXISTS_TAC `N:num` THEN ASM_REWRITE_TAC[IN_ELIM_THM] THEN ARITH_TAC;
783 DISCH_THEN(X_CHOOSE_THEN `n:num` MP_TAC) THEN
784 REWRITE_TAC[IN_ELIM_THM] THEN STRIP_TAC THEN
785 EXISTS_TAC `n:num` THEN ASM_REWRITE_TAC[] THEN
786 UNDISCH_TAC `n:num < N` THEN COND_CASES_TAC THEN
787 ASM_REWRITE_TAC[LT_REFL] THEN ARITH_TAC]]);;
789 let NUM_COUNTABLE = prove_by_refinement(
790 `COUNTABLE (UNIV:num->bool)`,
794 REWRITE_TAC[COUNTABLE;CARD_GE_REFL];
799 let NUM2_COUNTABLE = prove_by_refinement(
800 `COUNTABLE {((x:num),(y:num)) | T}`,
803 CHOOSE_TAC (ISPECL[`(0,0)`;`(\ (a:num,b:num) (n:num) . if (b=0) then (0,a+b+1) else (a+1,b-1))`] num_RECURSION);
804 REWRITE_TAC[COUNTABLE;GE_C;IN_ELIM_THM'];
806 EXISTS_TAC `fn:num -> (num#num)`;
807 X_GEN_TAC `p:num#num`;
808 REPEAT (DISCH_THEN (CHOOSE_THEN MP_TAC));
809 DISCH_THEN (fun t->REWRITE_TAC[t]);
810 REWRITE_TAC[IN_UNIV];
811 SUBGOAL_MP_TAC `?t. t = x'+|y'`;
813 SPEC_TAC (`x':num`,`a:num`);
814 SPEC_TAC (`y':num`,`b:num`);
815 CONV_TAC (quant_left_CONV "t");
816 CONV_TAC (quant_left_CONV "t");
817 CONV_TAC (quant_left_CONV "t");
821 DISCH_THEN (fun t -> REWRITE_TAC[t]);
824 CONV_TAC (quant_left_CONV "a");
828 USE 1 (SPECL [`0`;`t:num`]);
829 UND 1 THEN REDUCE_TAC;
830 DISCH_THEN (X_CHOOSE_TAC `n:num`);
832 USE 0 (SPEC `n:num`);
835 DISCH_THEN (fun t-> REWRITE_TAC[GSYM t]);
836 CONV_TAC (ONCE_DEPTH_CONV GEN_BETA_CONV);
844 REWRITE_TAC [ARITH_RULE `SUC t = t+|1`];
846 ABBREV_TAC `t' = SUC t`;
847 USE 2 (SPEC `SUC b`);
851 REWRITE_TAC[ARITH_RULE `SUC a +| b = a +| SUC b`];
852 DISCH_THEN (X_CHOOSE_TAC `n:num`);
855 USE 0 (SPEC `n:num`);
858 DISCH_THEN (fun t->REWRITE_TAC[GSYM t]);
859 CONV_TAC (ONCE_DEPTH_CONV GEN_BETA_CONV);
862 DISCH_THEN (fun t->REWRITE_TAC[t]);
863 REWRITE_TAC[ARITH_RULE `SUC a = a+| 1`];
867 let COUNTABLE_UNIONS = prove_by_refinement(
868 `!A:(A->bool)->bool. (COUNTABLE A) /\
869 (!a. (a IN A) ==> (COUNTABLE a)) ==> (COUNTABLE (UNIONS A))`,
874 USE 0 (REWRITE_RULE[COUNTABLE;GE_C;IN_UNIV]);
876 USE 0 (CONV_RULE (quant_left_CONV "x"));
877 USE 0 (CONV_RULE (quant_left_CONV "x"));
879 USE 1 (REWRITE_RULE[COUNTABLE;GE_C;IN_UNIV]);
880 USE 1 (CONV_RULE (quant_left_CONV "f"));
881 USE 1 (CONV_RULE (quant_left_CONV "f"));
883 DISCH_THEN (X_CHOOSE_TAC `g:(A->bool)->num->A`);
884 SUBGOAL_MP_TAC `!a y. (a IN (A:(A->bool)->bool)) /\ (y IN a) ==> (? (u:num) (v:num). ( a = f u) /\ (y = g a v))`;
887 USE 1 (SPEC `a:A->bool`);
888 USE 0 (SPEC `a:A->bool`);
889 EXISTS_TAC `(x:(A->bool)->num) a`;
891 ASSUME_TAC NUM2_COUNTABLE;
892 USE 2 (REWRITE_RULE[COUNTABLE;GE_C;IN_ELIM_THM';IN_UNIV]);
893 USE 2 (CONV_RULE NAME_CONFLICT_CONV);
894 UND 2 THEN (DISCH_THEN (X_CHOOSE_TAC `h:num->(num#num)`));
896 REWRITE_TAC[COUNTABLE;GE_C;IN_ELIM_THM';IN_UNIV;IN_UNIONS];
897 EXISTS_TAC `(\p. (g:(A->bool)->num->A) ((f:num->(A->bool)) (FST ((h:num->(num#num)) p))) (SND (h p)))`;
900 DISCH_THEN (CHOOSE_THEN MP_TAC);
902 USE 3 (SPEC `t:A->bool`);
904 UND 3 THEN (ASM_REWRITE_TAC[]);
905 REPEAT (DISCH_THEN(CHOOSE_THEN (MP_TAC)));
907 USE 2 (SPEC `(u:num,v:num)`);
908 SUBGOAL_MP_TAC `?x' y'. (u:num,v:num) = (x',y')`;
913 DISCH_THEN (CHOOSE_THEN (ASSUME_TAC o GSYM));
919 let COUNTABLE_IMAGE = prove_by_refinement(
920 `!(A:A->bool) (B:B->bool) . (COUNTABLE A) /\ (?f. (B SUBSET IMAGE f A)) ==>
924 REWRITE_TAC[COUNTABLE;GE_C;IN_UNIV;IN_ELIM_THM';SUBSET];
927 USE 1 (REWRITE_RULE[IMAGE;IN_ELIM_THM']);
929 USE 1 (REWRITE_RULE[IN_ELIM_THM']);
930 USE 1 (CONV_RULE NAME_CONFLICT_CONV);
931 EXISTS_TAC `(f':A->B) o (f:num->A)`;
937 DISCH_THEN CHOOSE_TAC;
939 UND 0 THEN (ASM_REWRITE_TAC[]) THEN DISCH_TAC;
944 let COUNTABLE_CARD = prove_by_refinement(
945 `!(A:A->bool) (B:B->bool). (COUNTABLE A) /\ (A >=_c B) ==>
951 MATCH_MP_TAC COUNTABLE_IMAGE;
952 EXISTS_TAC `A:A->bool`;
954 REWRITE_TAC[IMAGE;SUBSET;IN_ELIM_THM'];
955 USE 1 (REWRITE_RULE[GE_C]);
963 let COUNTABLE_NUMSEG = prove_by_refinement(
964 `!n. COUNTABLE {x | x <| n}`,
968 REWRITE_TAC[COUNTABLE;GE_C;IN_UNIV];
969 EXISTS_TAC `I:num->num`;
971 REWRITE_TAC[IN_ELIM_THM'];
976 let FINITE_COUNTABLE = prove_by_refinement(
977 `!(A:A->bool). (FINITE A) ==> (COUNTABLE A)`,
981 USE 0 (MATCH_MP FINITE_HAS_SIZE_LEMMA);
983 ASSUME_TAC(SPEC `n:num` COUNTABLE_NUMSEG);
985 USE 0 (MATCH_MP COUNTABLE_CARD);
990 let num_infinite = prove_by_refinement(
991 `~ (FINITE (UNIV:num->bool))`,
995 USE 0 (REWRITE_RULE[]);
996 USE 0 (MATCH_MP num_FINITE_AVOID);
997 USE 0 (REWRITE_RULE[IN_UNIV]);
1002 let num_SEG_UNION = prove_by_refinement(
1003 `!i. ({u | i <| u} UNION {m | m <=| i}) = UNIV`,
1007 SUBGOAL_MP_TAC `({u | i <| u} UNION {m | m <=| i}) = UNIV`;
1008 MATCH_MP_TAC EQ_EXT;
1010 REWRITE_TAC[UNIV;UNION;IN_ELIM_THM'];
1016 let num_above_infinite = prove_by_refinement(
1017 `!i. ~ (FINITE {u | i <| u})`,
1022 USE 0 (REWRITE_RULE[]);
1023 ASSUME_TAC(SPEC `i:num` FINITE_NUMSEG_LE);
1025 USE 0 (MATCH_MP FINITE_UNION_IMP);
1026 SUBGOAL_MP_TAC `({u | i <| u} UNION {m | m <=| i}) = UNIV`;
1027 REWRITE_TAC[num_SEG_UNION];
1031 REWRITE_TAC[num_infinite];
1035 let INTER_FINITE = prove_by_refinement(
1036 `!s (t:A->bool). (FINITE s ==> FINITE(s INTER t)) /\ (FINITE t ==> FINITE (s INTER t))`,
1040 CONV_TAC (quant_right_CONV "t");
1041 CONV_TAC (quant_right_CONV "s");
1044 SUBGOAL_MP_TAC `s INTER t SUBSET (s:A->bool)`;
1046 ASM_MESON_TAC[FINITE_SUBSET];
1047 MESON_TAC[INTER_COMM];
1052 let num_above_finite = prove_by_refinement(
1053 `!i J. (FINITE (J INTER {u | (i <| u)})) ==> (FINITE J)`,
1057 SUBGOAL_MP_TAC `J = (J INTER {u | (i <| u)}) UNION (J INTER {m | m <=| i})`;
1058 REWRITE_TAC[GSYM UNION_OVER_INTER;num_SEG_UNION;INTER_UNIV];
1060 ASM (ONCE_REWRITE_TAC)[];
1061 REWRITE_TAC[FINITE_UNION];
1063 MP_TAC (SPEC `i:num` FINITE_NUMSEG_LE);
1064 REWRITE_TAC[INTER_FINITE];
1068 let SUBSET_SUC = prove_by_refinement(
1069 `!(f:num->A->bool). (!i. f i SUBSET f (SUC i)) ==> (! i j. ( i <=| j) ==> (f i SUBSET f j))`,
1075 MP_TAC (prove( `?n. n = j -| i`,MESON_TAC[]));
1076 CONV_TAC (quant_left_CONV "n");
1077 SPEC_TAC (`i:num`,`i:num`);
1078 SPEC_TAC (`j:num`,`j:num`);
1079 REP 2( CONV_TAC (quant_left_CONV "n"));
1084 USE 1 (CONV_RULE REDUCE_CONV);
1085 ASM_REWRITE_TAC[SUBSET];
1088 SUBGOAL_MP_TAC `?j'. j = SUC j'`;
1089 DISJ_CASES_TAC (SPEC `j:num` num_CASES);
1094 DISCH_THEN CHOOSE_TAC;
1096 USE 0 (SPEC `j':num`);
1097 USE 1(SPECL [`j':num`;`i:num`]);
1099 SUBGOAL_MP_TAC `(n = j'-|i)`;
1104 SUBGOAL_MP_TAC `(i<=| j')`;
1105 USE 2 (MATCH_MP(ARITH_RULE `(SUC n = j -| i) ==> (0 < j -| i)`));
1113 ASM_MESON_TAC[SUBSET_TRANS];
1117 let SUBSET_SUC2 = prove_by_refinement(
1118 `!(f:num->A->bool). (!i. f (SUC i) SUBSET (f i)) ==> (! i j. ( i <=| j) ==> (f j SUBSET f i))`,
1124 MP_TAC (prove( `?n. n = j -| i`,MESON_TAC[]));
1125 CONV_TAC (quant_left_CONV "n");
1126 SPEC_TAC (`i:num`,`i:num`);
1127 SPEC_TAC (`j:num`,`j:num`);
1128 REP 2( CONV_TAC (quant_left_CONV "n"));
1133 USE 1 (CONV_RULE REDUCE_CONV);
1134 ASM_REWRITE_TAC[SUBSET];
1137 SUBGOAL_MP_TAC `?j'. j = SUC j'`;
1138 DISJ_CASES_TAC (SPEC `j:num` num_CASES);
1143 DISCH_THEN CHOOSE_TAC;
1145 USE 0 (SPEC `j':num`);
1146 USE 1(SPECL [`j':num`;`i:num`]);
1148 SUBGOAL_MP_TAC `(n = j'-|i)`;
1153 SUBGOAL_MP_TAC `(i<=| j')`;
1154 USE 2 (MATCH_MP(ARITH_RULE `(SUC n = j -| i) ==> (0 < j -| i)`));
1162 ASM_MESON_TAC[SUBSET_TRANS];
1166 let INFINITE_PIGEONHOLE = prove_by_refinement(
1167 `!I (f:A->B) B C. (~(FINITE {i | (I i) /\ (C (f i))})) /\ (FINITE B) /\
1168 (C SUBSET (UNIONS B)) ==>
1169 (?b. (B b) /\ ~(FINITE {i | (I i) /\ (C INTER b) (f i) }))`,
1174 USE 3 ( CONV_RULE (quant_left_CONV "b"));
1176 TAUT_TAC `P ==> (~P ==> F)`;
1177 SUBGOAL_MP_TAC `{i | I' i /\ (C ((f:A->B) i))} = UNIONS (IMAGE (\b. {i | I' i /\ ((C INTER b) (f i))}) B)`;
1178 REWRITE_TAC[UNIONS;IN_IMAGE];
1179 MATCH_MP_TAC EQ_EXT;
1181 REWRITE_TAC[IN_ELIM_THM'];
1182 ABBREV_TAC `j = (x:A)`;
1185 USE 2 (REWRITE_RULE [SUBSET;UNIONS]);
1186 USE 2 (REWRITE_RULE[IN_ELIM_THM']);
1187 USE 2 (SPEC `(f:A->B) j`);
1188 USE 2 (REWRITE_RULE[IN]);
1191 CONV_TAC (quant_left_CONV "x");
1192 CONV_TAC (quant_left_CONV "x");
1193 EXISTS_TAC (`u:B->bool`);
1195 EXISTS_TAC (`{i' | I' i' /\ (C INTER u) ((f:A->B) i')}`);
1197 REWRITE_TAC[IN_ELIM_THM';INTER];
1205 USE 4 (REWRITE_RULE[IN_ELIM_THM';INTER]);
1206 USE 4 (REWRITE_RULE[IN]);
1210 SUBGOAL_MP_TAC `FINITE (IMAGE (\b. {i | I' i /\ (C INTER b) ((f:A->B) i)}) B)`;
1211 MATCH_MP_TAC FINITE_IMAGE;
1213 SIMP_TAC[FINITE_UNIONS];
1216 REWRITE_TAC[IN_IMAGE];
1217 DISCH_THEN (X_CHOOSE_TAC `b:B->bool`);
1219 USE 3 (SPEC `b:B->bool`);
1223 ABBREV_TAC `r = {i | I' i /\ (C INTER b) ((f:A->B) i)}`;
1228 let real_FINITE = prove_by_refinement(
1229 `!(s:real->bool). FINITE s ==> (?a. !x. x IN s ==> (x <=. a))`,
1233 ASSUME_TAC REAL_ARCH_SIMPLE;
1234 USE 1 (CONV_RULE (quant_left_CONV "n"));
1236 SUBGOAL_MP_TAC `FINITE (IMAGE (n:real->num) s)`;
1237 ASM_MESON_TAC[FINITE_IMAGE];
1238 (*** JRH -- num_FINITE is now an equivalence not an implication
1239 ASSUME_TAC (SPEC `IMAGE (n:real->num) s` num_FINITE);
1241 ASSUME_TAC(fst(EQ_IMP_RULE(SPEC `IMAGE (n:real->num) s` num_FINITE)));
1245 USE 2 (REWRITE_RULE[IN_IMAGE]);
1246 USE 2 (CONV_RULE NAME_CONFLICT_CONV);
1249 USE 2 (CONV_RULE (quant_left_CONV "x'"));
1250 USE 2 (CONV_RULE (quant_left_CONV "x'"));
1251 USE 2 (SPEC `x:real`);
1252 USE 2 (SPEC `(n:real->num) x`);
1255 USE 1 (SPEC `x:real`);
1257 MATCH_MP_TAC (REAL_ARITH `a<=b ==> ((x <= a) ==> (x <=. b))`);
1263 let UNIONS_DELETE = prove_by_refinement(
1264 `!s. (UNIONS (s:(A->bool)->bool)) = (UNIONS (s DELETE (EMPTY)))`,
1267 REWRITE_TAC[UNIONS;DELETE;EMPTY];
1269 MATCH_MP_TAC EQ_EXT;
1270 REWRITE_TAC[IN_ELIM_THM'];
1278 (* ------------------------------------------------------------------ *)
1279 (* Partial functions, which we identify with functions that
1280 take the canonical choice of element outside the domain. *)
1281 (* ------------------------------------------------------------------ *)
1283 let SUPP = new_definition
1284 `SUPP (f:A->B) = \ x. ~(f x = (CHOICE (UNIV:B ->bool)) )`;;
1286 let FUN = new_definition
1287 `FUN a b = (\ (f:A->B). ((!x. (x IN a) ==> (f x IN b)) /\
1288 ((SUPP f) SUBSET a))) `;;
1290 (* ------------------------------------------------------------------ *)
1292 (* ------------------------------------------------------------------ *)
1294 let compose = new_definition
1295 `compose f g = \x. (f (g x))`;;
1297 let COMP_ASSOC = prove_by_refinement(
1298 `!(f:num ->num) (g:num->num) (h:num->num).
1299 (compose f (compose g h)) = (compose (compose f g) h)`,
1303 REPEAT GEN_TAC THEN REWRITE_TAC[compose];
1307 let COMP_INJ = prove (`!(f:A->B) (g:B->C) s t u.
1308 INJ f s t /\ (INJ g t u) ==>
1309 (INJ (compose g f) s u)`,
1312 EVERY[REPEAT GEN_TAC;
1313 REWRITE_TAC[INJ;compose];
1318 let COMP_SURJ = prove (`!(f:A->B) (g:B->C) s t u.
1319 SURJ f s t /\ (SURJ g t u) ==> (SURJ (compose g f) s u)`,
1322 EVERY[REWRITE_TAC[SURJ;compose];
1327 let COMP_BIJ = prove (`!(f:A->B) s t (g:B->C) u.
1328 BIJ f s t /\ (BIJ g t u) ==> (BIJ (compose g f) s u)`,
1335 ASM_MESON_TAC[COMP_INJ;COMP_SURJ]]);;
1340 (* ------------------------------------------------------------------ *)
1341 (* general construction of an inverse function on a domain *)
1342 (* ------------------------------------------------------------------ *)
1344 let INVERSE_FN = prove_by_refinement(
1345 `?INVERSE. (! (f:A->B) a b. (SURJ f a b) ==> ((INJ (INVERSE f a b) b a) /\
1346 (!(x:B). (x IN b) ==> (f ((INVERSE f a b) x) = x))))`,
1350 REWRITE_TAC[GSYM SKOLEM_THM];
1352 MATCH_MP_TAC (prove_by_refinement( `!A B. (A ==> (?x. (B x))) ==> (?(x:B->A). (A ==> (B x)))`,[MESON_TAC[]])) ;
1353 REWRITE_TAC[SURJ;INJ];
1355 SUBGOAL_MP_TAC `?u. !y. ((y IN b)==> ((u y IN a) /\ ((f:A->B) (u y) = y)))`;
1356 REWRITE_TAC[GSYM SKOLEM_THM];
1359 DISCH_THEN CHOOSE_TAC;
1360 EXISTS_TAC `u:B->A`;
1365 FIRST_X_ASSUM (fun th -> ASSUME_TAC (AP_TERM `f:A->B` th));
1372 let INVERSE_DEF = new_specification ["INVERSE"] INVERSE_FN;;
1374 let INVERSE_BIJ = prove_by_refinement(
1375 `!(f:A->B) a b. (BIJ f a b) ==> ((BIJ (INVERSE f a b) b a))`,
1381 ASM_SIMP_TAC[INVERSE_DEF];
1384 ASM_MESON_TAC[INVERSE_DEF;INJ];
1385 GEN_TAC THEN DISCH_TAC;
1386 EXISTS_TAC `(f:A->B) x`;
1389 SUBGOAL_THEN `((f:A->B) x) IN b` ASSUME_TAC;
1391 SUBGOAL_THEN `(f:A->B) (INVERSE f a b (f x)) = (f x)` ASSUME_TAC;
1392 ASM_MESON_TAC[INVERSE_DEF];
1393 H_UNDISCH_TAC (HYP "0");
1396 FIRST_X_ASSUM (fun th -> MP_TAC (SPECL [`INVERSE (f:A->B) a b (f x)`;`x:A`] th));
1399 SUBGOAL_THEN `INVERSE (f:A->B) a b (f x) IN a` ASSUME_TAC;
1400 ASM_MESON_TAC[INVERSE_DEF;INJ];
1405 let INVERSE_XY = prove_by_refinement(
1406 `!(f:A->B) a b x y. (BIJ f a b) /\ (x IN a) /\ (y IN b) ==> ((INVERSE f a b y = x) <=> (f x = y))`,
1412 FIRST_X_ASSUM (fun th -> (ASSUME_TAC th THEN (ASSUME_TAC (MATCH_MP INVERSE_DEF (CONJUNCT2 (REWRITE_RULE[BIJ] th))))));
1414 POP_ASSUM (fun th -> (ASSUME_TAC th THEN (ASSUME_TAC (CONJUNCT2 (REWRITE_RULE[INJ] (CONJUNCT1 (REWRITE_RULE[BIJ] th)))))));
1415 DISCH_THEN (fun th -> ASSUME_TAC th THEN (REWRITE_TAC[GSYM th]));
1416 FIRST_X_ASSUM MATCH_MP_TAC;
1419 IMP_RES_THEN ASSUME_TAC INVERSE_BIJ;
1420 ASM_MESON_TAC[BIJ;INJ];
1422 FIRST_X_ASSUM (fun th -> (ASSUME_TAC (CONJUNCT2 (REWRITE_RULE[BIJ] th))));
1423 IMP_RES_THEN (fun th -> ASSUME_TAC (CONJUNCT2 th)) INVERSE_DEF;
1428 let FINITE_BIJ = prove(
1429 `!a b (f:A->B). FINITE a /\ (BIJ f a b) ==> (FINITE b)`,
1432 MESON_TAC[SURJ_IMAGE;BIJ;INJ;FINITE_IMAGE]
1437 let FINITE_INJ = prove_by_refinement(
1438 `!a b (f:A->B). FINITE b /\ (INJ f a b) ==> (FINITE a)`,
1444 MP_TAC (SPECL [`f:A->B`;`b:B->bool`;`a:A->bool`] FINITE_IMAGE_INJ_GENERAL);
1446 SUBGOAL_THEN `(a:A->bool) SUBSET ({x | (x IN a) /\ ((f:A->B) x IN b)})` ASSUME_TAC;
1447 REWRITE_TAC[SUBSET];
1449 REWRITE_TAC[IN_ELIM_THM];
1451 ASM_MESON_TAC[BIJ;INJ];
1452 MATCH_MP_TAC FINITE_SUBSET;
1453 EXISTS_TAC `({x | (x IN a) /\ ((f:A->B) x IN b)})` ;
1455 FIRST_X_ASSUM (fun th -> MATCH_MP_TAC th);
1457 ASM_MESON_TAC[BIJ;INJ];
1465 let FINITE_BIJ2 = prove_by_refinement(
1466 `!a b (f:A->B). FINITE b /\ (BIJ f a b) ==> (FINITE a)`,
1470 MESON_TAC[BIJ;FINITE_INJ]
1474 let BIJ_CARD = prove_by_refinement(
1475 `!a b (f:A->B). FINITE a /\ (BIJ f a b) ==> (CARD a = (CARD b))`,
1479 ASM_MESON_TAC[SURJ_IMAGE;BIJ;INJ;CARD_IMAGE_INJ];
1484 let PAIR_LEMMA = prove_by_refinement(
1485 `!(x:num#num) i j. ((FST x = i) /\ (SND x = j)) <=> (x = (i,j))` ,
1489 MESON_TAC[FST;SND;PAIR];
1493 let CARD_SING = prove_by_refinement(
1494 `!(u:A->bool). (SING u ) ==> (CARD u = 1)`,
1499 DISCH_THEN (CHOOSE_TAC);
1501 ASSUME_TAC FINITE_RULES;
1502 ASM_SIMP_TAC[CARD_CLAUSES;NOT_IN_EMPTY];
1503 ACCEPT_TAC (NUM_RED_CONV `SUC 0`)
1507 let FINITE_SING = prove_by_refinement(
1508 `!(x:A). FINITE ({x})`,
1512 MESON_TAC[FINITE_RULES]
1516 let NUM_INTRO = prove_by_refinement(
1517 `!f P.((!(n:num). !(g:A). (f g = n) ==> (P g)) ==> (!g. (P g)))`,
1524 H_VAL (SPECL [`(f:A->num) (g:A)`; `g:A`]) (HYP "0");
1531 (* ------------------------------------------------------------------ *)
1532 (* Lemmas about the support of a function *)
1533 (* ------------------------------------------------------------------ *)
1536 (* Law of cardinal exponents B^0 = 1 *)
1537 let DOMAIN_EMPTY = prove_by_refinement(
1538 `!b. FUN (EMPTY:A->bool) b = { (\ (u:A). (CHOICE (UNIV:B->bool))) }`,
1542 REWRITE_TAC[EXTENSION;FUN];
1544 REWRITE_TAC[IN_ELIM_THM;INSERT;NOT_IN_EMPTY;SUBSET_EMPTY;SUPP];
1546 ONCE_REWRITE_TAC[EXTENSION];
1549 DISCH_TAC THEN (MATCH_MP_TAC EQ_EXT);
1552 DISCH_TAC THEN (ASM_REWRITE_TAC[]) THEN BETA_TAC;
1556 (* Law of cardinal exponents B^A * B = B^(A+1) *)
1557 let DOMAIN_INSERT = prove_by_refinement(
1558 `!a b s. (~((s:A) IN a) ==>
1559 (?F. (BIJ F (FUN (s INSERT a) b)
1560 { (u,v) | (u IN (FUN a b)) /\ ((v:B) IN b) }
1566 EXISTS_TAC `\ f. ((\ x. (if (x=(s:A)) then (CHOICE (UNIV:B->bool)) else (f x))),(f s))`;
1567 REWRITE_TAC[BIJ;INJ;SURJ];
1568 TAUT_TAC `(A /\ (A ==> B) /\ (A ==>C)) ==> ((A/\ B) /\ (A /\ C))`;
1570 X_GEN_TAC `(f:A->B)`;
1571 REWRITE_TAC[FUN;IN_ELIM_THM];
1572 REWRITE_TAC[INSERT;SUBSET];
1573 REWRITE_TAC[IN_ELIM_THM;SUPP];
1575 ABBREV_TAC `g = \ x. (if (x=(s:A)) then (CHOICE (UNIV:B->bool)) else (f x)) `;
1576 EXISTS_TAC `g:A->B`;
1577 EXISTS_TAC `(f:A->B) s`;
1580 EXPAND_TAC "g" THEN BETA_TAC;
1582 REWRITE_TAC[IN;COND_ELIM_THM];
1585 EXPAND_TAC "g" THEN BETA_TAC;
1587 ASM_CASES_TAC `(x:A) = s`;
1594 REWRITE_TAC[FUN;SUPP];
1596 X_GEN_TAC `f1:A->B`;
1597 X_GEN_TAC `f2:A->B`;
1600 MATCH_MP_TAC EQ_EXT;
1602 ASM_CASES_TAC `(x:A) = s`;
1603 POPL_TAC[1;2;3;4;6;7];
1605 ASM_MESON_TAC[PAIR;FST;SND];
1606 POPL_TAC[1;2;3;4;6;7];
1607 FIRST_X_ASSUM (fun th -> ASSUME_TAC (REWRITE_RULE[FST] (AP_TERM `FST:((A->B)#B)->(A->B)` th))) ;
1608 FIRST_X_ASSUM (fun th -> ASSUME_TAC (REWRITE_RULE[COND_ELIM_THM] (BETA_RULE (AP_THM th `x:A`))));
1610 H_UNDISCH_TAC (HYP "0");
1615 REWRITE_TAC[FUN;SUPP;IN_ELIM_THM];
1616 REWRITE_TAC[IN;INSERT;SUBSET];
1618 X_GEN_TAC `p:(A->B)#B`;
1619 DISCH_THEN CHOOSE_TAC;
1620 FIRST_X_ASSUM (fun th -> MP_TAC th);
1621 DISCH_THEN CHOOSE_TAC;
1622 FIRST_X_ASSUM MP_TAC;
1625 EXISTS_TAC `\ (x:A). if (x = s) then (v:B) else (u x)`;
1629 REWRITE_TAC[IN_ELIM_THM;COND_ELIM_THM];
1634 REWRITE_TAC[IN_ELIM_THM;COND_ELIM_THM];
1635 ASM_CASES_TAC `(t:A) = s`;
1636 POPL_TAC[1;3;4;5;6];
1638 POPL_TAC[1;3;4;5;6];
1639 FIRST_X_ASSUM (fun th -> ASSUME_TAC (SPEC `t:A` th));
1640 ASM_SIMP_TAC[prove(`~((t:A)=s) ==> ((t=s)=F)`,MESON_TAC[])];
1646 MATCH_MP_TAC EQ_EXT;
1649 DISJ_CASES_TAC (prove(`(((t:A)=s) <=> T) \/ ((t=s) <=> F)`,MESON_TAC[]));
1656 let CARD_DELETE_CHOICE = prove_by_refinement(
1657 `!(a:(A->bool)). ((FINITE a) /\ (~(a=EMPTY))) ==>
1658 (SUC (CARD (a DELETE (CHOICE a))) = (CARD a))`,
1663 ASM_SIMP_TAC[CARD_DELETE];
1664 ASM_SIMP_TAC[CHOICE_DEF];
1665 MATCH_MP_TAC (ARITH_RULE `~(x=0) ==> (SUC (x -| 1) = x)`);
1666 ASM_MESON_TAC[HAS_SIZE_0;HAS_SIZE];
1672 let dets_flag = ref true;;
1673 dets_flag:= !labels_flag;;
1677 (* labels_flag:=false;; *)
1679 (* Law of cardinals |B^A| = |B|^|A| *)
1681 Refinement.enhanced_prove_by_refinement false ALL_TAC (
1682 `!b a. (FINITE (a:A->bool)) /\ (FINITE (b:B->bool))
1683 ==> ((FUN a b) HAS_SIZE ((CARD b) EXP (CARD a)))`,
1687 MATCH_MP_TAC (SPEC `CARD:(A->bool)->num` ((INST_TYPE) [`:A->bool`,`:A`] NUM_INTRO));
1693 SUBGOAL_THEN `(a:A->bool) = EMPTY` ASSUME_TAC;
1694 ASM_REWRITE_TAC[GSYM HAS_SIZE_0;HAS_SIZE];
1695 ASM_REWRITE_TAC[HAS_SIZE;DOMAIN_EMPTY];
1697 REWRITE_TAC[FINITE_SING];
1698 MATCH_MP_TAC CARD_SING;
1702 FIRST_X_ASSUM (fun th -> ASSUME_TAC (SPEC `(a:A->bool) DELETE (CHOICE a)` th)) ;
1704 SUBGOAL_THEN `CARD ((a:A->bool) DELETE (CHOICE a)) = n` ASSUME_TAC;
1705 ASM_SIMP_TAC[CARD_DELETE];
1706 SUBGOAL_THEN `CHOICE (a:A->bool) IN a` ASSUME_TAC;
1707 MATCH_MP_TAC CHOICE_DEF;
1708 ASSUME_TAC( ARITH_RULE `!x. (x = (SUC n)) ==> (~(x = 0))`);
1709 REWRITE_TAC[GSYM HAS_SIZE_0;HAS_SIZE];
1712 MESON_TAC[ ( ARITH_RULE `!n. (SUC n -| 1) = n`)];
1714 H_MATCH_MP (HYP "3") (HYP "4");
1715 SUBGOAL_THEN `FUN ((a:A->bool) DELETE CHOICE a) (b:B->bool) HAS_SIZE CARD b **| CARD (a DELETE CHOICE a)` ASSUME_TAC;
1716 ASM_MESON_TAC[FINITE_DELETE];
1717 ASSUME_TAC (SPECL [`((a:A->bool) DELETE (CHOICE a))`;`b:B->bool`;`(CHOICE (a:A->bool))` ] DOMAIN_INSERT);
1719 H_UNDISCH_TAC (HYP "5");
1720 REWRITE_TAC[IN_DELETE];
1721 SUBGOAL_THEN `~((a:A->bool) = EMPTY)` ASSUME_TAC;
1722 REWRITE_TAC[GSYM HAS_SIZE_0;HAS_SIZE];
1723 ASSUME_TAC( ARITH_RULE `!x. (x = (SUC n)) ==> (~(x = 0))`);
1725 ASM_SIMP_TAC[INSERT_DELETE;CHOICE_DEF];
1726 DISCH_THEN CHOOSE_TAC;
1727 REWRITE_TAC[HAS_SIZE];
1728 SUBGOAL_THEN `FINITE (FUN (a:A->bool) (b:B->bool))` ASSUME_TAC;
1729 (* CONJ_TAC; *) ALL_TAC;
1730 MATCH_MP_TAC (SPEC `FUN (a:A->bool) (b:B->bool)` (PINST[(`:A->B`,`:A`);(`:(A->B)#B`,`:B`)] [] FINITE_BIJ2));
1731 EXISTS_TAC `{u,v | (u:A->B) IN FUN (a DELETE CHOICE a) b /\ (v:B) IN b}`;
1732 EXISTS_TAC `F':(A->B)->((A->B)#B)`;
1734 MATCH_MP_TAC FINITE_PRODUCT;
1736 ASM_MESON_TAC[HAS_SIZE];
1738 SUBGOAL_THEN `CARD (FUN (a:A->bool) (b:B->bool)) = (CARD {u,v | (u:A->B) IN FUN (a DELETE CHOICE a) b /\ (v:B) IN b})` ASSUME_TAC;
1739 MATCH_MP_TAC BIJ_CARD;
1740 EXISTS_TAC `F':(A->B)->((A->B)#B)`;
1744 SUBGOAL_THEN `FINITE (a DELETE CHOICE (a:A->bool))` ASSUME_TAC;
1745 ASM_MESON_TAC[FINITE_DELETE];
1746 SUBGOAL_THEN `(FUN ((a:A->bool) DELETE CHOICE a) (b:B->bool)) HAS_SIZE (CARD b **| (CARD (a DELETE CHOICE a)))` ASSUME_TAC;
1747 POPL_TAC[1;2;3;4;5;10;11];
1748 ASM_MESON_TAC[CARD_DELETE];
1749 POP_ASSUM (fun th -> ASSUME_TAC (REWRITE_RULE[HAS_SIZE] th) THEN (ASSUME_TAC th));
1750 ASM_SIMP_TAC[CARD_PRODUCT];
1751 REWRITE_TAC[EXP;MULT_AC]
1755 (* labels_flag:= true;; *)
1758 (* ------------------------------------------------------------------ *)
1759 (* ------------------------------------------------------------------ *)
1763 (* Definitions in math tend to be n-tuples of data. Let's make it
1764 easy to pick out the individual components of a definition *)
1766 (* pick out the rest of n-tuples. Indexing consistent with lib.drop *)
1767 let drop0 = new_definition(`drop0 (u:A#B) = SND u`);;
1768 let drop1 = new_definition(`drop1 (u:A#B#C) = SND (SND u)`);;
1769 let drop2 = new_definition(`drop2 (u:A#B#C#D) = SND (SND (SND u))`);;
1770 let drop3 = new_definition(`drop3 (u:A#B#C#D#E) = SND (SND (SND (SND u)))`);;
1772 (* pick out parts of n-tuples *)
1774 let part0 = new_definition(`part0 (u:A#B) = FST u`);;
1775 let part1 = new_definition(`part1 (u:A#B#C) = FST (drop0 u)`);;
1776 let part2 = new_definition(`part2 (u:A#B#C#D) = FST (drop1 u)`);;
1777 let part3 = new_definition(`part3 (u:A#B#C#D#E) = FST (drop2 u)`);;
1778 let part4 = new_definition(`part4 (u:A#B#C#D#E#F) = FST (drop3 u)`);;
1779 let part5 = new_definition(`part5 (u:A#B#C#D#E#F#G) =
1780 FST (SND (SND (SND (SND (SND u)))))`);;
1781 let part6 = new_definition(`part6 (u:A#B#C#D#E#F#G#H) =
1782 FST (SND (SND (SND (SND (SND (SND u))))))`);;
1783 let part7 = new_definition(`part7 (u:A#B#C#D#E#F#G#H#I) =
1784 FST (SND (SND (SND (SND (SND (SND (SND u)))))))`);;
1785 let part8 = new_definition(`part8 (u:A#B#C#D#E#F#G#H#I#J) =
1786 FST (SND (SND (SND (SND (SND (SND (SND (SND u))))))))`);;