1 (* Title: HOL/Big_Operators.thy
2 Author: Tobias Nipkow, Lawrence C Paulson and Markus Wenzel
3 with contributions by Jeremy Avigad
6 header {* Big operators and finite (non-empty) sets *}
12 subsection {* Generic monoid operation over a set *}
14 no_notation times (infixl "*" 70)
15 no_notation Groups.one ("1")
17 locale comm_monoid_big = comm_monoid +
18 fixes F :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b set \<Rightarrow> 'a"
19 assumes F_eq: "F g A = (if finite A then fold_image (op *) g 1 A else 1)"
21 sublocale comm_monoid_big < folding_image proof
24 context comm_monoid_big
27 lemma infinite [simp]:
28 "\<not> finite A \<Longrightarrow> F g A = 1"
32 assumes "A = B" "\<And>x. x \<in> B \<Longrightarrow> h x = g x"
36 with assms show ?thesis unfolding `A = B` by (simp cong: cong)
38 assume "\<not> finite A"
39 then show ?thesis unfolding `A = B` by simp
43 fixes P :: "'b \<Rightarrow> bool" and g h :: "'b \<Rightarrow> 'a"
44 assumes fA: "finite A"
45 shows "F (\<lambda>x. if P x then h x else g x) A =
46 F h (A \<inter> {x. P x}) * F g (A \<inter> - {x. P x})"
48 have a: "A = A \<inter> {x. P x} \<union> A \<inter> -{x. P x}"
49 "(A \<inter> {x. P x}) \<inter> (A \<inter> -{x. P x}) = {}"
52 have f: "finite (A \<inter> {x. P x})" "finite (A \<inter> -{x. P x})" by auto
53 let ?g = "\<lambda>x. if P x then h x else g x"
54 from union_disjoint[OF f a(2), of ?g] a(1)
56 by (subst (1 2) F_cong) simp_all
61 text {* for ad-hoc proofs for @{const fold_image} *}
63 lemma (in comm_monoid_add) comm_monoid_mult:
64 "class.comm_monoid_mult (op +) 0"
65 proof qed (auto intro: add_assoc add_commute)
67 notation times (infixl "*" 70)
68 notation Groups.one ("1")
71 subsection {* Generalized summation over a set *}
73 definition (in comm_monoid_add) setsum :: "('b \<Rightarrow> 'a) => 'b set => 'a" where
74 "setsum f A = (if finite A then fold_image (op +) f 0 A else 0)"
76 sublocale comm_monoid_add < setsum!: comm_monoid_big "op +" 0 setsum proof
80 Setsum ("\<Sum>_" [1000] 999) where
81 "\<Sum>A == setsum (%x. x) A"
83 text{* Now: lot's of fancy syntax. First, @{term "setsum (%x. e) A"} is
84 written @{text"\<Sum>x\<in>A. e"}. *}
87 "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add" ("(3SUM _:_. _)" [0, 51, 10] 10)
89 "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add" ("(3\<Sum>_\<in>_. _)" [0, 51, 10] 10)
91 "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add" ("(3\<Sum>_\<in>_. _)" [0, 51, 10] 10)
93 translations -- {* Beware of argument permutation! *}
94 "SUM i:A. b" == "CONST setsum (%i. b) A"
95 "\<Sum>i\<in>A. b" == "CONST setsum (%i. b) A"
97 text{* Instead of @{term"\<Sum>x\<in>{x. P}. e"} we introduce the shorter
98 @{text"\<Sum>x|P. e"}. *}
101 "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3SUM _ |/ _./ _)" [0,0,10] 10)
103 "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Sum>_ | (_)./ _)" [0,0,10] 10)
105 "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Sum>_ | (_)./ _)" [0,0,10] 10)
108 "SUM x|P. t" => "CONST setsum (%x. t) {x. P}"
109 "\<Sum>x|P. t" => "CONST setsum (%x. t) {x. P}"
113 fun setsum_tr' [Abs (x, Tx, t), Const (@{const_syntax Collect}, _) $ Abs (y, Ty, P)] =
114 if x <> y then raise Match
117 val x' = Syntax_Trans.mark_bound x;
118 val t' = subst_bound (x', t);
119 val P' = subst_bound (x', P);
120 in Syntax.const @{syntax_const "_qsetsum"} $ Syntax_Trans.mark_bound x $ P' $ t' end
121 | setsum_tr' _ = raise Match;
122 in [(@{const_syntax setsum}, setsum_tr')] end
127 by (fact setsum.empty)
130 "finite F ==> a \<notin> F ==> setsum f (insert a F) = f a + setsum f F"
131 by (fact setsum.insert)
133 lemma setsum_infinite:
134 "~ finite A ==> setsum f A = 0"
135 by (fact setsum.infinite)
137 lemma (in comm_monoid_add) setsum_reindex:
138 assumes "inj_on f B" shows "setsum h (f ` B) = setsum (h \<circ> f) B"
140 interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
141 from assms show ?thesis by (auto simp add: setsum_def fold_image_reindex dest!:finite_imageD)
144 lemma (in comm_monoid_add) setsum_reindex_id:
145 "inj_on f B ==> setsum f B = setsum id (f ` B)"
146 by (simp add: setsum_reindex)
148 lemma (in comm_monoid_add) setsum_reindex_nonzero:
149 assumes fS: "finite S"
150 and nz: "\<And> x y. x \<in> S \<Longrightarrow> y \<in> S \<Longrightarrow> x \<noteq> y \<Longrightarrow> f x = f y \<Longrightarrow> h (f x) = 0"
151 shows "setsum h (f ` S) = setsum (h o f) S"
153 proof(induct rule: finite_induct[OF fS])
154 case 1 thus ?case by simp
157 {assume fxF: "f x \<in> f ` F" hence "\<exists>y \<in> F . f y = f x" by auto
158 then obtain y where y: "y \<in> F" "f x = f y" by auto
159 from "2.hyps" y have xy: "x \<noteq> y" by auto
161 from "2.prems"[of x y] "2.hyps" xy y have h0: "h (f x) = 0" by simp
162 have "setsum h (f ` insert x F) = setsum h (f ` F)" using fxF by auto
163 also have "\<dots> = setsum (h o f) (insert x F)"
164 unfolding setsum.insert[OF `finite F` `x\<notin>F`]
167 apply (rule "2.hyps"(3))
168 apply (rule_tac y="y" in "2.prems")
171 finally have ?case .}
173 {assume fxF: "f x \<notin> f ` F"
174 have "setsum h (f ` insert x F) = h (f x) + setsum h (f ` F)"
175 using fxF "2.hyps" by simp
176 also have "\<dots> = setsum (h o f) (insert x F)"
177 unfolding setsum.insert[OF `finite F` `x\<notin>F`]
179 apply (rule cong [OF refl [of "op + (h (f x))"]])
180 apply (rule "2.hyps"(3))
181 apply (rule_tac y="y" in "2.prems")
184 finally have ?case .}
185 ultimately show ?case by blast
188 lemma (in comm_monoid_add) setsum_cong:
189 "A = B ==> (!!x. x:B ==> f x = g x) ==> setsum f A = setsum g B"
190 by (cases "finite A") (auto intro: setsum.cong)
192 lemma (in comm_monoid_add) strong_setsum_cong [cong]:
193 "A = B ==> (!!x. x:B =simp=> f x = g x)
194 ==> setsum (%x. f x) A = setsum (%x. g x) B"
195 by (rule setsum_cong) (simp_all add: simp_implies_def)
197 lemma (in comm_monoid_add) setsum_cong2: "\<lbrakk>\<And>x. x \<in> A \<Longrightarrow> f x = g x\<rbrakk> \<Longrightarrow> setsum f A = setsum g A"
198 by (auto intro: setsum_cong)
200 lemma (in comm_monoid_add) setsum_reindex_cong:
201 "[|inj_on f A; B = f ` A; !!a. a:A \<Longrightarrow> g a = h (f a)|]
202 ==> setsum h B = setsum g A"
203 by (simp add: setsum_reindex)
205 lemma (in comm_monoid_add) setsum_0[simp]: "setsum (%i. 0) A = 0"
206 by (cases "finite A") (erule finite_induct, auto)
208 lemma (in comm_monoid_add) setsum_0': "ALL a:A. f a = 0 ==> setsum f A = 0"
209 by (simp add:setsum_cong)
211 lemma (in comm_monoid_add) setsum_Un_Int: "finite A ==> finite B ==>
212 setsum g (A Un B) + setsum g (A Int B) = setsum g A + setsum g B"
213 -- {* The reversed orientation looks more natural, but LOOPS as a simprule! *}
214 by (fact setsum.union_inter)
216 lemma (in comm_monoid_add) setsum_Un_disjoint: "finite A ==> finite B
217 ==> A Int B = {} ==> setsum g (A Un B) = setsum g A + setsum g B"
218 by (fact setsum.union_disjoint)
220 lemma setsum_mono_zero_left:
221 assumes fT: "finite T" and ST: "S \<subseteq> T"
222 and z: "\<forall>i \<in> T - S. f i = 0"
223 shows "setsum f S = setsum f T"
225 have eq: "T = S \<union> (T - S)" using ST by blast
226 have d: "S \<inter> (T - S) = {}" using ST by blast
227 from fT ST have f: "finite S" "finite (T - S)" by (auto intro: finite_subset)
229 by (simp add: setsum_Un_disjoint[OF f d, unfolded eq[symmetric]] setsum_0'[OF z])
232 lemma setsum_mono_zero_right:
233 "finite T \<Longrightarrow> S \<subseteq> T \<Longrightarrow> \<forall>i \<in> T - S. f i = 0 \<Longrightarrow> setsum f T = setsum f S"
234 by(blast intro!: setsum_mono_zero_left[symmetric])
236 lemma setsum_mono_zero_cong_left:
237 assumes fT: "finite T" and ST: "S \<subseteq> T"
238 and z: "\<forall>i \<in> T - S. g i = 0"
239 and fg: "\<And>x. x \<in> S \<Longrightarrow> f x = g x"
240 shows "setsum f S = setsum g T"
242 have eq: "T = S \<union> (T - S)" using ST by blast
243 have d: "S \<inter> (T - S) = {}" using ST by blast
244 from fT ST have f: "finite S" "finite (T - S)" by (auto intro: finite_subset)
246 using fg by (simp add: setsum_Un_disjoint[OF f d, unfolded eq[symmetric]] setsum_0'[OF z])
249 lemma setsum_mono_zero_cong_right:
250 assumes fT: "finite T" and ST: "S \<subseteq> T"
251 and z: "\<forall>i \<in> T - S. f i = 0"
252 and fg: "\<And>x. x \<in> S \<Longrightarrow> f x = g x"
253 shows "setsum f T = setsum g S"
254 using setsum_mono_zero_cong_left[OF fT ST z] fg[symmetric] by auto
257 assumes fS: "finite S"
258 shows "setsum (\<lambda>k. if k=a then b k else 0) S = (if a \<in> S then b a else 0)"
260 let ?f = "(\<lambda>k. if k=a then b k else 0)"
261 {assume a: "a \<notin> S"
262 hence "\<forall> k\<in> S. ?f k = 0" by simp
263 hence ?thesis using a by simp}
265 {assume a: "a \<in> S"
268 have eq: "S = ?A \<union> ?B" using a by blast
269 have dj: "?A \<inter> ?B = {}" by simp
270 from fS have fAB: "finite ?A" "finite ?B" by auto
271 have "setsum ?f S = setsum ?f ?A + setsum ?f ?B"
272 using setsum_Un_disjoint[OF fAB dj, of ?f, unfolded eq[symmetric]]
274 then have ?thesis using a by simp}
275 ultimately show ?thesis by blast
278 assumes fS: "finite S" shows
279 "setsum (\<lambda>k. if a = k then b k else 0) S =
280 (if a\<in> S then b a else 0)"
281 using setsum_delta[OF fS, of a b, symmetric]
282 by (auto intro: setsum_cong)
284 lemma setsum_restrict_set:
285 assumes fA: "finite A"
286 shows "setsum f (A \<inter> B) = setsum (\<lambda>x. if x \<in> B then f x else 0) A"
288 from fA have fab: "finite (A \<inter> B)" by auto
289 have aba: "A \<inter> B \<subseteq> A" by blast
290 let ?g = "\<lambda>x. if x \<in> A\<inter>B then f x else 0"
291 from setsum_mono_zero_left[OF fA aba, of ?g]
296 assumes fA: "finite A"
297 shows "setsum (\<lambda>x. if P x then f x else g x) A =
298 setsum f (A \<inter> {x. P x}) + setsum g (A \<inter> - {x. P x})"
299 using setsum.If_cases[OF fA] .
301 (*But we can't get rid of finite I. If infinite, although the rhs is 0,
302 the lhs need not be, since UNION I A could still be finite.*)
303 lemma (in comm_monoid_add) setsum_UN_disjoint:
304 assumes "finite I" and "ALL i:I. finite (A i)"
305 and "ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {}"
306 shows "setsum f (UNION I A) = (\<Sum>i\<in>I. setsum f (A i))"
308 interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
309 from assms show ?thesis by (simp add: setsum_def fold_image_UN_disjoint)
312 text{*No need to assume that @{term C} is finite. If infinite, the rhs is
313 directly 0, and @{term "Union C"} is also infinite, hence the lhs is also 0.*}
314 lemma setsum_Union_disjoint:
315 assumes "\<forall>A\<in>C. finite A" "\<forall>A\<in>C. \<forall>B\<in>C. A \<noteq> B \<longrightarrow> A Int B = {}"
316 shows "setsum f (Union C) = setsum (setsum f) C"
319 from setsum_UN_disjoint[OF this assms]
321 by (simp add: SUP_def)
322 qed (force dest: finite_UnionD simp add: setsum_def)
324 (*But we can't get rid of finite A. If infinite, although the lhs is 0,
325 the rhs need not be, since SIGMA A B could still be finite.*)
326 lemma (in comm_monoid_add) setsum_Sigma:
327 assumes "finite A" and "ALL x:A. finite (B x)"
328 shows "(\<Sum>x\<in>A. (\<Sum>y\<in>B x. f x y)) = (\<Sum>(x,y)\<in>(SIGMA x:A. B x). f x y)"
330 interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
331 from assms show ?thesis by (simp add: setsum_def fold_image_Sigma split_def)
334 text{*Here we can eliminate the finiteness assumptions, by cases.*}
335 lemma setsum_cartesian_product:
336 "(\<Sum>x\<in>A. (\<Sum>y\<in>B. f x y)) = (\<Sum>(x,y) \<in> A <*> B. f x y)"
337 apply (cases "finite A")
338 apply (cases "finite B")
339 apply (simp add: setsum_Sigma)
340 apply (cases "A={}", simp)
342 apply (auto simp add: setsum_def
343 dest: finite_cartesian_productD1 finite_cartesian_productD2)
346 lemma (in comm_monoid_add) setsum_addf: "setsum (%x. f x + g x) A = (setsum f A + setsum g A)"
347 by (cases "finite A") (simp_all add: setsum.distrib)
350 subsubsection {* Properties in more restricted classes of structures *}
352 lemma setsum_SucD: "setsum f A = Suc n ==> EX a:A. 0 < f a"
353 apply (case_tac "finite A")
354 prefer 2 apply (simp add: setsum_def)
356 apply (erule finite_induct, auto)
359 lemma setsum_eq_0_iff [simp]:
360 "finite F ==> (setsum f F = 0) = (ALL a:F. f a = (0::nat))"
361 by (induct set: finite) auto
363 lemma setsum_eq_Suc0_iff: "finite A \<Longrightarrow>
364 (setsum f A = Suc 0) = (EX a:A. f a = Suc 0 & (ALL b:A. a\<noteq>b \<longrightarrow> f b = 0))"
365 apply(erule finite_induct)
366 apply (auto simp add:add_is_1)
369 lemmas setsum_eq_1_iff = setsum_eq_Suc0_iff[simplified One_nat_def[symmetric]]
371 lemma setsum_Un_nat: "finite A ==> finite B ==>
372 (setsum f (A Un B) :: nat) = setsum f A + setsum f B - setsum f (A Int B)"
373 -- {* For the natural numbers, we have subtraction. *}
374 by (subst setsum_Un_Int [symmetric], auto simp add: algebra_simps)
376 lemma setsum_Un: "finite A ==> finite B ==>
377 (setsum f (A Un B) :: 'a :: ab_group_add) =
378 setsum f A + setsum f B - setsum f (A Int B)"
379 by (subst setsum_Un_Int [symmetric], auto simp add: algebra_simps)
381 lemma (in comm_monoid_add) setsum_eq_general_reverses:
382 assumes fS: "finite S" and fT: "finite T"
383 and kh: "\<And>y. y \<in> T \<Longrightarrow> k y \<in> S \<and> h (k y) = y"
384 and hk: "\<And>x. x \<in> S \<Longrightarrow> h x \<in> T \<and> k (h x) = x \<and> g (h x) = f x"
385 shows "setsum f S = setsum g T"
387 interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
389 apply (simp add: setsum_def fS fT)
390 apply (rule fold_image_eq_general_inverses)
397 lemma (in comm_monoid_add) setsum_Un_zero:
398 assumes fS: "finite S" and fT: "finite T"
399 and I0: "\<forall>x \<in> S\<inter>T. f x = 0"
400 shows "setsum f (S \<union> T) = setsum f S + setsum f T"
402 interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
405 apply (simp add: setsum_def)
406 apply (rule fold_image_Un_one)
410 lemma setsum_UNION_zero:
411 assumes fS: "finite S" and fSS: "\<forall>T \<in> S. finite T"
412 and f0: "\<And>T1 T2 x. T1\<in>S \<Longrightarrow> T2\<in>S \<Longrightarrow> T1 \<noteq> T2 \<Longrightarrow> x \<in> T1 \<Longrightarrow> x \<in> T2 \<Longrightarrow> f x = 0"
413 shows "setsum f (\<Union>S) = setsum (\<lambda>T. setsum f T) S"
415 proof(induct rule: finite_induct[OF fS])
416 case 1 thus ?case by simp
419 then have fTF: "finite T" "\<forall>T\<in>F. finite T" "finite F" and TF: "T \<notin> F"
420 and H: "setsum f (\<Union> F) = setsum (setsum f) F" by auto
421 from fTF have fUF: "finite (\<Union>F)" by auto
422 from "2.prems" TF fTF
424 by (auto simp add: H[symmetric] intro: setsum_Un_zero[OF fTF(1) fUF, of f])
427 lemma setsum_diff1_nat: "(setsum f (A - {a}) :: nat) =
428 (if a:A then setsum f A - f a else setsum f A)"
429 apply (case_tac "finite A")
430 prefer 2 apply (simp add: setsum_def)
431 apply (erule finite_induct)
432 apply (auto simp add: insert_Diff_if)
433 apply (drule_tac a = a in mk_disjoint_insert, auto)
436 lemma setsum_diff1: "finite A \<Longrightarrow>
437 (setsum f (A - {a}) :: ('a::ab_group_add)) =
438 (if a:A then setsum f A - f a else setsum f A)"
439 by (erule finite_induct) (auto simp add: insert_Diff_if)
441 lemma setsum_diff1'[rule_format]:
442 "finite A \<Longrightarrow> a \<in> A \<longrightarrow> (\<Sum> x \<in> A. f x) = f a + (\<Sum> x \<in> (A - {a}). f x)"
443 apply (erule finite_induct[where F=A and P="% A. (a \<in> A \<longrightarrow> (\<Sum> x \<in> A. f x) = f a + (\<Sum> x \<in> (A - {a}). f x))"])
444 apply (auto simp add: insert_Diff_if add_ac)
447 lemma setsum_diff1_ring: assumes "finite A" "a \<in> A"
448 shows "setsum f (A - {a}) = setsum f A - (f a::'a::ring)"
449 unfolding setsum_diff1'[OF assms] by auto
451 (* By Jeremy Siek: *)
453 lemma setsum_diff_nat:
454 assumes "finite B" and "B \<subseteq> A"
455 shows "(setsum f (A - B) :: nat) = (setsum f A) - (setsum f B)"
458 show "setsum f (A - {}) = (setsum f A) - (setsum f {})" by simp
460 fix F x assume finF: "finite F" and xnotinF: "x \<notin> F"
461 and xFinA: "insert x F \<subseteq> A"
462 and IH: "F \<subseteq> A \<Longrightarrow> setsum f (A - F) = setsum f A - setsum f F"
463 from xnotinF xFinA have xinAF: "x \<in> (A - F)" by simp
464 from xinAF have A: "setsum f ((A - F) - {x}) = setsum f (A - F) - f x"
465 by (simp add: setsum_diff1_nat)
466 from xFinA have "F \<subseteq> A" by simp
467 with IH have "setsum f (A - F) = setsum f A - setsum f F" by simp
468 with A have B: "setsum f ((A - F) - {x}) = setsum f A - setsum f F - f x"
470 from xnotinF have "A - insert x F = (A - F) - {x}" by auto
471 with B have C: "setsum f (A - insert x F) = setsum f A - setsum f F - f x"
473 from finF xnotinF have "setsum f (insert x F) = setsum f F + f x" by simp
474 with C have "setsum f (A - insert x F) = setsum f A - setsum f (insert x F)"
476 thus "setsum f (A - insert x F) = setsum f A - setsum f (insert x F)" by simp
480 assumes le: "finite A" "B \<subseteq> A"
481 shows "setsum f (A - B) = setsum f A - ((setsum f B)::('a::ab_group_add))"
483 from le have finiteB: "finite B" using finite_subset by auto
484 show ?thesis using finiteB le
490 thus ?case using le finiteB
491 by (simp add: Diff_insert[where a=x and B=F] setsum_diff1 insert_absorb)
496 assumes le: "\<And>i. i\<in>K \<Longrightarrow> f (i::'a) \<le> ((g i)::('b::{comm_monoid_add, ordered_ab_semigroup_add}))"
497 shows "(\<Sum>i\<in>K. f i) \<le> (\<Sum>i\<in>K. g i)"
498 proof (cases "finite K")
500 thus ?thesis using le
506 thus ?case using add_mono by fastforce
511 by (simp add: setsum_def)
514 lemma setsum_strict_mono:
515 fixes f :: "'a \<Rightarrow> 'b::{ordered_cancel_ab_semigroup_add,comm_monoid_add}"
516 assumes "finite A" "A \<noteq> {}"
517 and "!!x. x:A \<Longrightarrow> f x < g x"
518 shows "setsum f A < setsum g A"
520 proof (induct rule: finite_ne_induct)
521 case singleton thus ?case by simp
523 case insert thus ?case by (auto simp: add_strict_mono)
527 "setsum (%x. - (f x)::'a::ab_group_add) A = - setsum f A"
528 proof (cases "finite A")
529 case True thus ?thesis by (induct set: finite) auto
531 case False thus ?thesis by (simp add: setsum_def)
534 lemma setsum_subtractf:
535 "setsum (%x. ((f x)::'a::ab_group_add) - g x) A =
536 setsum f A - setsum g A"
537 proof (cases "finite A")
538 case True thus ?thesis by (simp add: diff_minus setsum_addf setsum_negf)
540 case False thus ?thesis by (simp add: setsum_def)
544 assumes nn: "\<forall>x\<in>A. (0::'a::{ordered_ab_semigroup_add,comm_monoid_add}) \<le> f x"
545 shows "0 \<le> setsum f A"
546 proof (cases "finite A")
547 case True thus ?thesis using nn
549 case empty then show ?case by simp
552 then have "0 + 0 \<le> f x + setsum f F" by (blast intro: add_mono)
553 with insert show ?case by simp
556 case False thus ?thesis by (simp add: setsum_def)
560 assumes np: "\<forall>x\<in>A. f x \<le> (0::'a::{ordered_ab_semigroup_add,comm_monoid_add})"
561 shows "setsum f A \<le> 0"
562 proof (cases "finite A")
563 case True thus ?thesis using np
565 case empty then show ?case by simp
568 then have "f x + setsum f F \<le> 0 + 0" by (blast intro: add_mono)
569 with insert show ?case by simp
572 case False thus ?thesis by (simp add: setsum_def)
575 lemma setsum_nonneg_leq_bound:
576 fixes f :: "'a \<Rightarrow> 'b::{ordered_ab_group_add}"
577 assumes "finite s" "\<And>i. i \<in> s \<Longrightarrow> f i \<ge> 0" "(\<Sum>i \<in> s. f i) = B" "i \<in> s"
580 have "0 \<le> (\<Sum> i \<in> s - {i}. f i)" and "0 \<le> f i"
581 using assms by (auto intro!: setsum_nonneg)
583 have "(\<Sum> i \<in> s - {i}. f i) + f i = B"
584 using assms by (simp add: setsum_diff1)
585 ultimately show ?thesis by auto
588 lemma setsum_nonneg_0:
589 fixes f :: "'a \<Rightarrow> 'b::{ordered_ab_group_add}"
590 assumes "finite s" and pos: "\<And> i. i \<in> s \<Longrightarrow> f i \<ge> 0"
591 and "(\<Sum> i \<in> s. f i) = 0" and i: "i \<in> s"
593 using setsum_nonneg_leq_bound[OF assms] pos[OF i] by auto
596 fixes f :: "'a \<Rightarrow> 'b :: ordered_comm_monoid_add"
597 assumes fin: "finite B" and sub: "A \<subseteq> B" and nn: "\<And>b. b \<in> B-A \<Longrightarrow> 0 \<le> f b"
598 shows "setsum f A \<le> setsum f B"
600 have "setsum f A \<le> setsum f A + setsum f (B-A)"
601 by(simp add: add_increasing2[OF setsum_nonneg] nn Ball_def)
602 also have "\<dots> = setsum f (A \<union> (B-A))" using fin finite_subset[OF sub fin]
603 by (simp add:setsum_Un_disjoint del:Un_Diff_cancel)
604 also have "A \<union> (B-A) = B" using sub by blast
605 finally show ?thesis .
608 lemma setsum_mono3: "finite B ==> A <= B ==>
610 0 <= ((f x)::'a::{comm_monoid_add,ordered_ab_semigroup_add}) ==>
611 setsum f A <= setsum f B"
612 apply (subgoal_tac "setsum f B = setsum f A + setsum f (B - A)")
614 apply (subgoal_tac "setsum f A + 0 <= setsum f A + setsum f (B - A)")
616 apply (rule add_left_mono)
617 apply (erule setsum_nonneg)
618 apply (subst setsum_Un_disjoint [THEN sym])
619 apply (erule finite_subset, assumption)
620 apply (rule finite_subset)
623 apply (auto simp add: sup_absorb2)
626 lemma setsum_right_distrib:
627 fixes f :: "'a => ('b::semiring_0)"
628 shows "r * setsum f A = setsum (%n. r * f n) A"
629 proof (cases "finite A")
633 case empty thus ?case by simp
635 case (insert x A) thus ?case by (simp add: right_distrib)
638 case False thus ?thesis by (simp add: setsum_def)
641 lemma setsum_left_distrib:
642 "setsum f A * (r::'a::semiring_0) = (\<Sum>n\<in>A. f n * r)"
643 proof (cases "finite A")
647 case empty thus ?case by simp
649 case (insert x A) thus ?case by (simp add: left_distrib)
652 case False thus ?thesis by (simp add: setsum_def)
655 lemma setsum_divide_distrib:
656 "setsum f A / (r::'a::field) = (\<Sum>n\<in>A. f n / r)"
657 proof (cases "finite A")
661 case empty thus ?case by simp
663 case (insert x A) thus ?case by (simp add: add_divide_distrib)
666 case False thus ?thesis by (simp add: setsum_def)
669 lemma setsum_abs[iff]:
670 fixes f :: "'a => ('b::ordered_ab_group_add_abs)"
671 shows "abs (setsum f A) \<le> setsum (%i. abs(f i)) A"
672 proof (cases "finite A")
676 case empty thus ?case by simp
679 thus ?case by (auto intro: abs_triangle_ineq order_trans)
682 case False thus ?thesis by (simp add: setsum_def)
685 lemma setsum_abs_ge_zero[iff]:
686 fixes f :: "'a => ('b::ordered_ab_group_add_abs)"
687 shows "0 \<le> setsum (%i. abs(f i)) A"
688 proof (cases "finite A")
692 case empty thus ?case by simp
694 case (insert x A) thus ?case by auto
697 case False thus ?thesis by (simp add: setsum_def)
700 lemma abs_setsum_abs[simp]:
701 fixes f :: "'a => ('b::ordered_ab_group_add_abs)"
702 shows "abs (\<Sum>a\<in>A. abs(f a)) = (\<Sum>a\<in>A. abs(f a))"
703 proof (cases "finite A")
707 case empty thus ?case by simp
710 hence "\<bar>\<Sum>a\<in>insert a A. \<bar>f a\<bar>\<bar> = \<bar>\<bar>f a\<bar> + (\<Sum>a\<in>A. \<bar>f a\<bar>)\<bar>" by simp
711 also have "\<dots> = \<bar>\<bar>f a\<bar> + \<bar>\<Sum>a\<in>A. \<bar>f a\<bar>\<bar>\<bar>" using insert by simp
712 also have "\<dots> = \<bar>f a\<bar> + \<bar>\<Sum>a\<in>A. \<bar>f a\<bar>\<bar>"
713 by (simp del: abs_of_nonneg)
714 also have "\<dots> = (\<Sum>a\<in>insert a A. \<bar>f a\<bar>)" using insert by simp
718 case False thus ?thesis by (simp add: setsum_def)
722 fixes A :: "'a set" and B :: "'b set"
723 assumes fin: "finite A" "finite B"
724 shows "setsum f (A <+> B) = setsum (f \<circ> Inl) A + setsum (f \<circ> Inr) B"
726 have "A <+> B = Inl ` A \<union> Inr ` B" by auto
727 moreover from fin have "finite (Inl ` A :: ('a + 'b) set)" "finite (Inr ` B :: ('a + 'b) set)"
729 moreover have "Inl ` A \<inter> Inr ` B = ({} :: ('a + 'b) set)" by auto
730 moreover have "inj_on (Inl :: 'a \<Rightarrow> 'a + 'b) A" "inj_on (Inr :: 'b \<Rightarrow> 'a + 'b) B" by(auto intro: inj_onI)
731 ultimately show ?thesis using fin by(simp add: setsum_Un_disjoint setsum_reindex)
735 text {* Commuting outer and inner summation *}
737 lemma setsum_commute:
738 "(\<Sum>i\<in>A. \<Sum>j\<in>B. f i j) = (\<Sum>j\<in>B. \<Sum>i\<in>A. f i j)"
739 proof (simp add: setsum_cartesian_product)
740 have "(\<Sum>(x,y) \<in> A <*> B. f x y) =
741 (\<Sum>(y,x) \<in> (%(i, j). (j, i)) ` (A \<times> B). f x y)"
743 apply (simp add: setsum_reindex [where f = "%(i, j). (j, i)"] swap_inj_on)
744 apply (simp add: split_def)
746 also have "... = (\<Sum>(y,x)\<in>B \<times> A. f x y)"
748 apply (simp add: swap_product)
750 finally show "?s = ?t" .
753 lemma setsum_product:
754 fixes f :: "'a => ('b::semiring_0)"
755 shows "setsum f A * setsum g B = (\<Sum>i\<in>A. \<Sum>j\<in>B. f i * g j)"
756 by (simp add: setsum_right_distrib setsum_left_distrib) (rule setsum_commute)
758 lemma setsum_mult_setsum_if_inj:
759 fixes f :: "'a => ('b::semiring_0)"
760 shows "inj_on (%(a,b). f a * g b) (A \<times> B) ==>
761 setsum f A * setsum g B = setsum id {f a * g b|a b. a:A & b:B}"
762 by(auto simp: setsum_product setsum_cartesian_product
763 intro!: setsum_reindex_cong[symmetric])
765 lemma setsum_constant [simp]: "(\<Sum>x \<in> A. y) = of_nat(card A) * y"
766 apply (cases "finite A")
767 apply (erule finite_induct)
768 apply (auto simp add: algebra_simps)
771 lemma setsum_bounded:
772 assumes le: "\<And>i. i\<in>A \<Longrightarrow> f i \<le> (K::'a::{semiring_1, ordered_ab_semigroup_add})"
773 shows "setsum f A \<le> of_nat(card A) * K"
774 proof (cases "finite A")
776 thus ?thesis using le setsum_mono[where K=A and g = "%x. K"] by simp
778 case False thus ?thesis by (simp add: setsum_def)
782 subsubsection {* Cardinality as special case of @{const setsum} *}
784 lemma card_eq_setsum:
785 "card A = setsum (\<lambda>x. 1) A"
786 by (simp only: card_def setsum_def)
788 lemma card_UN_disjoint:
789 assumes "finite I" and "\<forall>i\<in>I. finite (A i)"
790 and "\<forall>i\<in>I. \<forall>j\<in>I. i \<noteq> j \<longrightarrow> A i \<inter> A j = {}"
791 shows "card (UNION I A) = (\<Sum>i\<in>I. card(A i))"
793 have "(\<Sum>i\<in>I. card (A i)) = (\<Sum>i\<in>I. \<Sum>x\<in>A i. 1)" by simp
794 with assms show ?thesis by (simp add: card_eq_setsum setsum_UN_disjoint del: setsum_constant)
797 lemma card_Union_disjoint:
798 "finite C ==> (ALL A:C. finite A) ==>
799 (ALL A:C. ALL B:C. A \<noteq> B --> A Int B = {})
800 ==> card (Union C) = setsum card C"
801 apply (frule card_UN_disjoint [of C id])
802 apply (simp_all add: SUP_def id_def)
805 text{*The image of a finite set can be expressed using @{term fold_image}.*}
806 lemma image_eq_fold_image:
807 "finite A ==> f ` A = fold_image (op Un) (%x. {f x}) {} A"
808 proof (induct rule: finite_induct)
809 case empty then show ?case by simp
811 interpret ab_semigroup_mult "op Un"
814 then show ?case by simp
817 subsubsection {* Cardinality of products *}
819 lemma card_SigmaI [simp]:
820 "\<lbrakk> finite A; ALL a:A. finite (B a) \<rbrakk>
821 \<Longrightarrow> card (SIGMA x: A. B x) = (\<Sum>a\<in>A. card (B a))"
822 by(simp add: card_eq_setsum setsum_Sigma del:setsum_constant)
825 lemma SigmaI_insert: "y \<notin> A ==>
826 (SIGMA x:(insert y A). B x) = (({y} <*> (B y)) \<union> (SIGMA x: A. B x))"
830 lemma card_cartesian_product: "card (A <*> B) = card(A) * card(B)"
831 by (cases "finite A \<and> finite B")
832 (auto simp add: card_eq_0_iff dest: finite_cartesian_productD1 finite_cartesian_productD2)
834 lemma card_cartesian_product_singleton: "card({x} <*> A) = card(A)"
835 by (simp add: card_cartesian_product)
838 subsection {* Generalized product over a set *}
840 definition (in comm_monoid_mult) setprod :: "('b \<Rightarrow> 'a) => 'b set => 'a" where
841 "setprod f A = (if finite A then fold_image (op *) f 1 A else 1)"
843 sublocale comm_monoid_mult < setprod!: comm_monoid_big "op *" 1 setprod proof
844 qed (fact setprod_def)
847 Setprod ("\<Prod>_" [1000] 999) where
848 "\<Prod>A == setprod (%x. x) A"
851 "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult" ("(3PROD _:_. _)" [0, 51, 10] 10)
853 "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult" ("(3\<Prod>_\<in>_. _)" [0, 51, 10] 10)
855 "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult" ("(3\<Prod>_\<in>_. _)" [0, 51, 10] 10)
857 translations -- {* Beware of argument permutation! *}
858 "PROD i:A. b" == "CONST setprod (%i. b) A"
859 "\<Prod>i\<in>A. b" == "CONST setprod (%i. b) A"
861 text{* Instead of @{term"\<Prod>x\<in>{x. P}. e"} we introduce the shorter
862 @{text"\<Prod>x|P. e"}. *}
865 "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3PROD _ |/ _./ _)" [0,0,10] 10)
867 "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Prod>_ | (_)./ _)" [0,0,10] 10)
869 "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Prod>_ | (_)./ _)" [0,0,10] 10)
872 "PROD x|P. t" => "CONST setprod (%x. t) {x. P}"
873 "\<Prod>x|P. t" => "CONST setprod (%x. t) {x. P}"
875 lemma setprod_empty: "setprod f {} = 1"
876 by (fact setprod.empty)
878 lemma setprod_insert: "[| finite A; a \<notin> A |] ==>
879 setprod f (insert a A) = f a * setprod f A"
880 by (fact setprod.insert)
882 lemma setprod_infinite: "~ finite A ==> setprod f A = 1"
883 by (fact setprod.infinite)
885 lemma setprod_reindex:
886 "inj_on f B ==> setprod h (f ` B) = setprod (h \<circ> f) B"
887 by(auto simp: setprod_def fold_image_reindex dest!:finite_imageD)
889 lemma setprod_reindex_id: "inj_on f B ==> setprod f B = setprod id (f ` B)"
890 by (auto simp add: setprod_reindex)
893 "A = B ==> (!!x. x:B ==> f x = g x) ==> setprod f A = setprod g B"
894 by(fastforce simp: setprod_def intro: fold_image_cong)
896 lemma strong_setprod_cong[cong]:
897 "A = B ==> (!!x. x:B =simp=> f x = g x) ==> setprod f A = setprod g B"
898 by(fastforce simp: simp_implies_def setprod_def intro: fold_image_cong)
900 lemma setprod_reindex_cong: "inj_on f A ==>
901 B = f ` A ==> g = h \<circ> f ==> setprod h B = setprod g A"
902 by (frule setprod_reindex, simp)
904 lemma strong_setprod_reindex_cong: assumes i: "inj_on f A"
905 and B: "B = f ` A" and eq: "\<And>x. x \<in> A \<Longrightarrow> g x = (h \<circ> f) x"
906 shows "setprod h B = setprod g A"
908 have "setprod h B = setprod (h o f) A"
909 by (simp add: B setprod_reindex[OF i, of h])
910 then show ?thesis apply simp
911 apply (rule setprod_cong)
916 lemma setprod_Un_one:
917 assumes fS: "finite S" and fT: "finite T"
918 and I0: "\<forall>x \<in> S\<inter>T. f x = 1"
919 shows "setprod f (S \<union> T) = setprod f S * setprod f T"
921 apply (simp add: setprod_def)
922 apply (rule fold_image_Un_one)
926 lemma setprod_1: "setprod (%i. 1) A = 1"
927 apply (case_tac "finite A")
928 apply (erule finite_induct, auto simp add: mult_ac)
931 lemma setprod_1': "ALL a:F. f a = 1 ==> setprod f F = 1"
932 apply (subgoal_tac "setprod f F = setprod (%x. 1) F")
933 apply (erule ssubst, rule setprod_1)
934 apply (rule setprod_cong, auto)
937 lemma setprod_Un_Int: "finite A ==> finite B
938 ==> setprod g (A Un B) * setprod g (A Int B) = setprod g A * setprod g B"
939 by(simp add: setprod_def fold_image_Un_Int[symmetric])
941 lemma setprod_Un_disjoint: "finite A ==> finite B
942 ==> A Int B = {} ==> setprod g (A Un B) = setprod g A * setprod g B"
943 by (subst setprod_Un_Int [symmetric], auto)
945 lemma setprod_mono_one_left:
946 assumes fT: "finite T" and ST: "S \<subseteq> T"
947 and z: "\<forall>i \<in> T - S. f i = 1"
948 shows "setprod f S = setprod f T"
950 have eq: "T = S \<union> (T - S)" using ST by blast
951 have d: "S \<inter> (T - S) = {}" using ST by blast
952 from fT ST have f: "finite S" "finite (T - S)" by (auto intro: finite_subset)
954 by (simp add: setprod_Un_disjoint[OF f d, unfolded eq[symmetric]] setprod_1'[OF z])
957 lemmas setprod_mono_one_right = setprod_mono_one_left [THEN sym]
960 assumes fS: "finite S"
961 shows "setprod (\<lambda>k. if k=a then b k else 1) S = (if a \<in> S then b a else 1)"
963 let ?f = "(\<lambda>k. if k=a then b k else 1)"
964 {assume a: "a \<notin> S"
965 hence "\<forall> k\<in> S. ?f k = 1" by simp
966 hence ?thesis using a by (simp add: setprod_1) }
968 {assume a: "a \<in> S"
971 have eq: "S = ?A \<union> ?B" using a by blast
972 have dj: "?A \<inter> ?B = {}" by simp
973 from fS have fAB: "finite ?A" "finite ?B" by auto
974 have fA1: "setprod ?f ?A = 1" apply (rule setprod_1') by auto
975 have "setprod ?f ?A * setprod ?f ?B = setprod ?f S"
976 using setprod_Un_disjoint[OF fAB dj, of ?f, unfolded eq[symmetric]]
978 then have ?thesis using a by (simp add: fA1 cong: setprod_cong cong del: if_weak_cong)}
979 ultimately show ?thesis by blast
982 lemma setprod_delta':
983 assumes fS: "finite S" shows
984 "setprod (\<lambda>k. if a = k then b k else 1) S =
985 (if a\<in> S then b a else 1)"
986 using setprod_delta[OF fS, of a b, symmetric]
987 by (auto intro: setprod_cong)
990 lemma setprod_UN_disjoint:
991 "finite I ==> (ALL i:I. finite (A i)) ==>
992 (ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {}) ==>
993 setprod f (UNION I A) = setprod (%i. setprod f (A i)) I"
994 by (simp add: setprod_def fold_image_UN_disjoint)
996 lemma setprod_Union_disjoint:
997 assumes "\<forall>A\<in>C. finite A" "\<forall>A\<in>C. \<forall>B\<in>C. A \<noteq> B \<longrightarrow> A Int B = {}"
998 shows "setprod f (Union C) = setprod (setprod f) C"
1001 from setprod_UN_disjoint[OF this assms]
1003 by (simp add: SUP_def)
1004 qed (force dest: finite_UnionD simp add: setprod_def)
1006 lemma setprod_Sigma: "finite A ==> ALL x:A. finite (B x) ==>
1007 (\<Prod>x\<in>A. (\<Prod>y\<in> B x. f x y)) =
1008 (\<Prod>(x,y)\<in>(SIGMA x:A. B x). f x y)"
1009 by(simp add:setprod_def fold_image_Sigma split_def)
1011 text{*Here we can eliminate the finiteness assumptions, by cases.*}
1012 lemma setprod_cartesian_product:
1013 "(\<Prod>x\<in>A. (\<Prod>y\<in> B. f x y)) = (\<Prod>(x,y)\<in>(A <*> B). f x y)"
1014 apply (cases "finite A")
1015 apply (cases "finite B")
1016 apply (simp add: setprod_Sigma)
1017 apply (cases "A={}", simp)
1018 apply (simp add: setprod_1)
1019 apply (auto simp add: setprod_def
1020 dest: finite_cartesian_productD1 finite_cartesian_productD2)
1023 lemma setprod_timesf:
1024 "setprod (%x. f x * g x) A = (setprod f A * setprod g A)"
1025 by(simp add:setprod_def fold_image_distrib)
1028 subsubsection {* Properties in more restricted classes of structures *}
1030 lemma setprod_eq_1_iff [simp]:
1031 "finite F ==> (setprod f F = 1) = (ALL a:F. f a = (1::nat))"
1032 by (induct set: finite) auto
1035 "finite A ==> EX x: A. f x = (0::'a::comm_semiring_1) ==> setprod f A = 0"
1036 apply (induct set: finite, force, clarsimp)
1037 apply (erule disjE, auto)
1040 lemma setprod_nonneg [rule_format]:
1041 "(ALL x: A. (0::'a::linordered_semidom) \<le> f x) --> 0 \<le> setprod f A"
1042 by (cases "finite A", induct set: finite, simp_all add: mult_nonneg_nonneg)
1044 lemma setprod_pos [rule_format]: "(ALL x: A. (0::'a::linordered_semidom) < f x)
1045 --> 0 < setprod f A"
1046 by (cases "finite A", induct set: finite, simp_all add: mult_pos_pos)
1048 lemma setprod_zero_iff[simp]: "finite A ==>
1049 (setprod f A = (0::'a::{comm_semiring_1,no_zero_divisors})) =
1051 by (erule finite_induct, auto simp:no_zero_divisors)
1053 lemma setprod_pos_nat:
1054 "finite S ==> (ALL x : S. f x > (0::nat)) ==> setprod f S > 0"
1055 using setprod_zero_iff by(simp del:neq0_conv add:neq0_conv[symmetric])
1057 lemma setprod_pos_nat_iff[simp]:
1058 "finite S ==> (setprod f S > 0) = (ALL x : S. f x > (0::nat))"
1059 using setprod_zero_iff by(simp del:neq0_conv add:neq0_conv[symmetric])
1061 lemma setprod_Un: "finite A ==> finite B ==> (ALL x: A Int B. f x \<noteq> 0) ==>
1062 (setprod f (A Un B) :: 'a ::{field})
1063 = setprod f A * setprod f B / setprod f (A Int B)"
1064 by (subst setprod_Un_Int [symmetric], auto)
1066 lemma setprod_diff1: "finite A ==> f a \<noteq> 0 ==>
1067 (setprod f (A - {a}) :: 'a :: {field}) =
1068 (if a:A then setprod f A / f a else setprod f A)"
1069 by (erule finite_induct) (auto simp add: insert_Diff_if)
1071 lemma setprod_inversef:
1072 fixes f :: "'b \<Rightarrow> 'a::field_inverse_zero"
1073 shows "finite A ==> setprod (inverse \<circ> f) A = inverse (setprod f A)"
1074 by (erule finite_induct) auto
1076 lemma setprod_dividef:
1077 fixes f :: "'b \<Rightarrow> 'a::field_inverse_zero"
1079 ==> setprod (%x. f x / g x) A = setprod f A / setprod g A"
1081 "setprod (%x. f x / g x) A = setprod (%x. f x * (inverse \<circ> g) x) A")
1082 apply (erule ssubst)
1083 apply (subst divide_inverse)
1084 apply (subst setprod_timesf)
1085 apply (subst setprod_inversef, assumption+, rule refl)
1086 apply (rule setprod_cong, rule refl)
1087 apply (subst divide_inverse, auto)
1090 lemma setprod_dvd_setprod [rule_format]:
1091 "(ALL x : A. f x dvd g x) \<longrightarrow> setprod f A dvd setprod g A"
1092 apply (cases "finite A")
1093 apply (induct set: finite)
1094 apply (auto simp add: dvd_def)
1095 apply (rule_tac x = "k * ka" in exI)
1096 apply (simp add: algebra_simps)
1099 lemma setprod_dvd_setprod_subset:
1100 "finite B \<Longrightarrow> A <= B \<Longrightarrow> setprod f A dvd setprod f B"
1101 apply (subgoal_tac "setprod f B = setprod f A * setprod f (B - A)")
1102 apply (unfold dvd_def, blast)
1103 apply (subst setprod_Un_disjoint [symmetric])
1104 apply (auto elim: finite_subset intro: setprod_cong)
1107 lemma setprod_dvd_setprod_subset2:
1108 "finite B \<Longrightarrow> A <= B \<Longrightarrow> ALL x : A. (f x::'a::comm_semiring_1) dvd g x \<Longrightarrow>
1109 setprod f A dvd setprod g B"
1110 apply (rule dvd_trans)
1111 apply (rule setprod_dvd_setprod, erule (1) bspec)
1112 apply (erule (1) setprod_dvd_setprod_subset)
1115 lemma dvd_setprod: "finite A \<Longrightarrow> i:A \<Longrightarrow>
1116 (f i ::'a::comm_semiring_1) dvd setprod f A"
1117 by (induct set: finite) (auto intro: dvd_mult)
1119 lemma dvd_setsum [rule_format]: "(ALL i : A. d dvd f i) \<longrightarrow>
1120 (d::'a::comm_semiring_1) dvd (SUM x : A. f x)"
1121 apply (cases "finite A")
1122 apply (induct set: finite)
1127 fixes f :: "'a \<Rightarrow> 'b\<Colon>linordered_semidom"
1128 assumes "\<forall>i\<in>A. 0 \<le> f i \<and> f i \<le> g i"
1129 shows "setprod f A \<le> setprod g A"
1130 proof (cases "finite A")
1132 hence ?thesis "setprod f A \<ge> 0" using subset_refl[of A]
1133 proof (induct A rule: finite_subset_induct)
1135 thus "setprod f (insert a F) \<le> setprod g (insert a F)" "0 \<le> setprod f (insert a F)"
1136 unfolding setprod_insert[OF insert(1,3)]
1137 using assms[rule_format,OF insert(2)] insert
1138 by (auto intro: mult_mono mult_nonneg_nonneg)
1140 thus ?thesis by simp
1144 fixes f :: "'a \<Rightarrow> 'b\<Colon>{linordered_field,abs}"
1145 shows "abs (setprod f A) = setprod (\<lambda>x. abs (f x)) A"
1146 proof (cases "finite A")
1147 case True thus ?thesis
1148 by induct (auto simp add: field_simps abs_mult)
1151 lemma setprod_constant: "finite A ==> (\<Prod>x\<in> A. (y::'a::{comm_monoid_mult})) = y^(card A)"
1152 apply (erule finite_induct)
1156 lemma setprod_gen_delta:
1157 assumes fS: "finite S"
1158 shows "setprod (\<lambda>k. if k=a then b k else c) S = (if a \<in> S then (b a ::'a::{comm_monoid_mult}) * c^ (card S - 1) else c^ card S)"
1160 let ?f = "(\<lambda>k. if k=a then b k else c)"
1161 {assume a: "a \<notin> S"
1162 hence "\<forall> k\<in> S. ?f k = c" by simp
1163 hence ?thesis using a setprod_constant[OF fS, of c] by (simp add: setprod_1 cong add: setprod_cong) }
1165 {assume a: "a \<in> S"
1168 have eq: "S = ?A \<union> ?B" using a by blast
1169 have dj: "?A \<inter> ?B = {}" by simp
1170 from fS have fAB: "finite ?A" "finite ?B" by auto
1171 have fA0:"setprod ?f ?A = setprod (\<lambda>i. c) ?A"
1172 apply (rule setprod_cong) by auto
1173 have cA: "card ?A = card S - 1" using fS a by auto
1174 have fA1: "setprod ?f ?A = c ^ card ?A" unfolding fA0 apply (rule setprod_constant) using fS by auto
1175 have "setprod ?f ?A * setprod ?f ?B = setprod ?f S"
1176 using setprod_Un_disjoint[OF fAB dj, of ?f, unfolded eq[symmetric]]
1178 then have ?thesis using a cA
1179 by (simp add: fA1 field_simps cong add: setprod_cong cong del: if_weak_cong)}
1180 ultimately show ?thesis by blast
1184 subsection {* Versions of @{const inf} and @{const sup} on non-empty sets *}
1186 no_notation times (infixl "*" 70)
1187 no_notation Groups.one ("1")
1189 locale semilattice_big = semilattice +
1190 fixes F :: "'a set \<Rightarrow> 'a"
1191 assumes F_eq: "finite A \<Longrightarrow> F A = fold1 (op *) A"
1193 sublocale semilattice_big < folding_one_idem proof
1194 qed (simp_all add: F_eq)
1196 notation times (infixl "*" 70)
1197 notation Groups.one ("1")
1202 definition Inf_fin :: "'a set \<Rightarrow> 'a" ("\<Sqinter>\<^bsub>fin\<^esub>_" [900] 900) where
1203 "Inf_fin = fold1 inf"
1205 definition Sup_fin :: "'a set \<Rightarrow> 'a" ("\<Squnion>\<^bsub>fin\<^esub>_" [900] 900) where
1206 "Sup_fin = fold1 sup"
1210 sublocale lattice < Inf_fin!: semilattice_big inf Inf_fin proof
1211 qed (simp add: Inf_fin_def)
1213 sublocale lattice < Sup_fin!: semilattice_big sup Sup_fin proof
1214 qed (simp add: Sup_fin_def)
1216 context semilattice_inf
1219 lemma ab_semigroup_idem_mult_inf:
1220 "class.ab_semigroup_idem_mult inf"
1221 proof qed (rule inf_assoc inf_commute inf_idem)+
1223 lemma fold_inf_insert[simp]: "finite A \<Longrightarrow> Finite_Set.fold inf b (insert a A) = inf a (Finite_Set.fold inf b A)"
1224 by(rule comp_fun_idem.fold_insert_idem[OF ab_semigroup_idem_mult.comp_fun_idem[OF ab_semigroup_idem_mult_inf]])
1226 lemma inf_le_fold_inf: "finite A \<Longrightarrow> ALL a:A. b \<le> a \<Longrightarrow> inf b c \<le> Finite_Set.fold inf c A"
1227 by (induct pred: finite) (auto intro: le_infI1)
1229 lemma fold_inf_le_inf: "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> Finite_Set.fold inf b A \<le> inf a b"
1230 proof(induct arbitrary: a pred:finite)
1231 case empty thus ?case by simp
1236 assume "A = {}" thus ?thesis using insert by simp
1238 assume "A \<noteq> {}" thus ?thesis using insert by (auto intro: le_infI2)
1242 lemma below_fold1_iff:
1243 assumes "finite A" "A \<noteq> {}"
1244 shows "x \<le> fold1 inf A \<longleftrightarrow> (\<forall>a\<in>A. x \<le> a)"
1246 interpret ab_semigroup_idem_mult inf
1247 by (rule ab_semigroup_idem_mult_inf)
1248 show ?thesis using assms by (induct rule: finite_ne_induct) simp_all
1254 shows "fold1 inf A \<le> a"
1256 from assms have "A \<noteq> {}" by auto
1257 from `finite A` `A \<noteq> {}` `a \<in> A` show ?thesis
1258 proof (induct rule: finite_ne_induct)
1259 case singleton thus ?case by simp
1261 interpret ab_semigroup_idem_mult inf
1262 by (rule ab_semigroup_idem_mult_inf)
1264 from insert(5) have "a = x \<or> a \<in> F" by simp
1267 assume "a = x" thus ?thesis using insert
1268 by (simp add: mult_ac)
1271 hence bel: "fold1 inf F \<le> a" by (rule insert)
1272 have "inf (fold1 inf (insert x F)) a = inf x (inf (fold1 inf F) a)"
1273 using insert by (simp add: mult_ac)
1274 also have "inf (fold1 inf F) a = fold1 inf F"
1275 using bel by (auto intro: antisym)
1276 also have "inf x \<dots> = fold1 inf (insert x F)"
1277 using insert by (simp add: mult_ac)
1278 finally have aux: "inf (fold1 inf (insert x F)) a = fold1 inf (insert x F)" .
1279 moreover have "inf (fold1 inf (insert x F)) a \<le> a" by simp
1280 ultimately show ?thesis by simp
1287 context semilattice_sup
1290 lemma ab_semigroup_idem_mult_sup: "class.ab_semigroup_idem_mult sup"
1291 by (rule semilattice_inf.ab_semigroup_idem_mult_inf)(rule dual_semilattice)
1293 lemma fold_sup_insert[simp]: "finite A \<Longrightarrow> Finite_Set.fold sup b (insert a A) = sup a (Finite_Set.fold sup b A)"
1294 by(rule semilattice_inf.fold_inf_insert)(rule dual_semilattice)
1296 lemma fold_sup_le_sup: "finite A \<Longrightarrow> ALL a:A. a \<le> b \<Longrightarrow> Finite_Set.fold sup c A \<le> sup b c"
1297 by(rule semilattice_inf.inf_le_fold_inf)(rule dual_semilattice)
1299 lemma sup_le_fold_sup: "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> sup a b \<le> Finite_Set.fold sup b A"
1300 by(rule semilattice_inf.fold_inf_le_inf)(rule dual_semilattice)
1307 lemma Inf_le_Sup [simp]: "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> \<Sqinter>\<^bsub>fin\<^esub>A \<le> \<Squnion>\<^bsub>fin\<^esub>A"
1308 apply(unfold Sup_fin_def Inf_fin_def)
1309 apply(subgoal_tac "EX a. a:A")
1310 prefer 2 apply blast
1312 apply(rule order_trans)
1313 apply(erule (1) fold1_belowI)
1314 apply(erule (1) semilattice_inf.fold1_belowI [OF dual_semilattice])
1317 lemma sup_Inf_absorb [simp]:
1318 "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> sup a (\<Sqinter>\<^bsub>fin\<^esub>A) = a"
1319 apply(subst sup_commute)
1320 apply(simp add: Inf_fin_def sup_absorb2 fold1_belowI)
1323 lemma inf_Sup_absorb [simp]:
1324 "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> inf a (\<Squnion>\<^bsub>fin\<^esub>A) = a"
1325 by (simp add: Sup_fin_def inf_absorb1
1326 semilattice_inf.fold1_belowI [OF dual_semilattice])
1330 context distrib_lattice
1333 lemma sup_Inf1_distrib:
1336 shows "sup x (\<Sqinter>\<^bsub>fin\<^esub>A) = \<Sqinter>\<^bsub>fin\<^esub>{sup x a|a. a \<in> A}"
1338 interpret ab_semigroup_idem_mult inf
1339 by (rule ab_semigroup_idem_mult_inf)
1340 from assms show ?thesis
1341 by (simp add: Inf_fin_def image_def
1342 hom_fold1_commute [where h="sup x", OF sup_inf_distrib1])
1343 (rule arg_cong [where f="fold1 inf"], blast)
1346 lemma sup_Inf2_distrib:
1347 assumes A: "finite A" "A \<noteq> {}" and B: "finite B" "B \<noteq> {}"
1348 shows "sup (\<Sqinter>\<^bsub>fin\<^esub>A) (\<Sqinter>\<^bsub>fin\<^esub>B) = \<Sqinter>\<^bsub>fin\<^esub>{sup a b|a b. a \<in> A \<and> b \<in> B}"
1349 using A proof (induct rule: finite_ne_induct)
1350 case singleton thus ?case
1351 by (simp add: sup_Inf1_distrib [OF B])
1353 interpret ab_semigroup_idem_mult inf
1354 by (rule ab_semigroup_idem_mult_inf)
1356 have finB: "finite {sup x b |b. b \<in> B}"
1357 by(rule finite_surj[where f = "sup x", OF B(1)], auto)
1358 have finAB: "finite {sup a b |a b. a \<in> A \<and> b \<in> B}"
1360 have "{sup a b |a b. a \<in> A \<and> b \<in> B} = (UN a:A. UN b:B. {sup a b})"
1362 thus ?thesis by(simp add: insert(1) B(1))
1364 have ne: "{sup a b |a b. a \<in> A \<and> b \<in> B} \<noteq> {}" using insert B by blast
1365 have "sup (\<Sqinter>\<^bsub>fin\<^esub>(insert x A)) (\<Sqinter>\<^bsub>fin\<^esub>B) = sup (inf x (\<Sqinter>\<^bsub>fin\<^esub>A)) (\<Sqinter>\<^bsub>fin\<^esub>B)"
1366 using insert by simp
1367 also have "\<dots> = inf (sup x (\<Sqinter>\<^bsub>fin\<^esub>B)) (sup (\<Sqinter>\<^bsub>fin\<^esub>A) (\<Sqinter>\<^bsub>fin\<^esub>B))" by(rule sup_inf_distrib2)
1368 also have "\<dots> = inf (\<Sqinter>\<^bsub>fin\<^esub>{sup x b|b. b \<in> B}) (\<Sqinter>\<^bsub>fin\<^esub>{sup a b|a b. a \<in> A \<and> b \<in> B})"
1369 using insert by(simp add:sup_Inf1_distrib[OF B])
1370 also have "\<dots> = \<Sqinter>\<^bsub>fin\<^esub>({sup x b |b. b \<in> B} \<union> {sup a b |a b. a \<in> A \<and> b \<in> B})"
1371 (is "_ = \<Sqinter>\<^bsub>fin\<^esub>?M")
1373 by (simp add: Inf_fin_def fold1_Un2 [OF finB _ finAB ne])
1374 also have "?M = {sup a b |a b. a \<in> insert x A \<and> b \<in> B}"
1376 finally show ?case .
1379 lemma inf_Sup1_distrib:
1380 assumes "finite A" and "A \<noteq> {}"
1381 shows "inf x (\<Squnion>\<^bsub>fin\<^esub>A) = \<Squnion>\<^bsub>fin\<^esub>{inf x a|a. a \<in> A}"
1383 interpret ab_semigroup_idem_mult sup
1384 by (rule ab_semigroup_idem_mult_sup)
1385 from assms show ?thesis
1386 by (simp add: Sup_fin_def image_def hom_fold1_commute [where h="inf x", OF inf_sup_distrib1])
1387 (rule arg_cong [where f="fold1 sup"], blast)
1390 lemma inf_Sup2_distrib:
1391 assumes A: "finite A" "A \<noteq> {}" and B: "finite B" "B \<noteq> {}"
1392 shows "inf (\<Squnion>\<^bsub>fin\<^esub>A) (\<Squnion>\<^bsub>fin\<^esub>B) = \<Squnion>\<^bsub>fin\<^esub>{inf a b|a b. a \<in> A \<and> b \<in> B}"
1393 using A proof (induct rule: finite_ne_induct)
1394 case singleton thus ?case
1395 by(simp add: inf_Sup1_distrib [OF B])
1398 have finB: "finite {inf x b |b. b \<in> B}"
1399 by(rule finite_surj[where f = "%b. inf x b", OF B(1)], auto)
1400 have finAB: "finite {inf a b |a b. a \<in> A \<and> b \<in> B}"
1402 have "{inf a b |a b. a \<in> A \<and> b \<in> B} = (UN a:A. UN b:B. {inf a b})"
1404 thus ?thesis by(simp add: insert(1) B(1))
1406 have ne: "{inf a b |a b. a \<in> A \<and> b \<in> B} \<noteq> {}" using insert B by blast
1407 interpret ab_semigroup_idem_mult sup
1408 by (rule ab_semigroup_idem_mult_sup)
1409 have "inf (\<Squnion>\<^bsub>fin\<^esub>(insert x A)) (\<Squnion>\<^bsub>fin\<^esub>B) = inf (sup x (\<Squnion>\<^bsub>fin\<^esub>A)) (\<Squnion>\<^bsub>fin\<^esub>B)"
1410 using insert by simp
1411 also have "\<dots> = sup (inf x (\<Squnion>\<^bsub>fin\<^esub>B)) (inf (\<Squnion>\<^bsub>fin\<^esub>A) (\<Squnion>\<^bsub>fin\<^esub>B))" by(rule inf_sup_distrib2)
1412 also have "\<dots> = sup (\<Squnion>\<^bsub>fin\<^esub>{inf x b|b. b \<in> B}) (\<Squnion>\<^bsub>fin\<^esub>{inf a b|a b. a \<in> A \<and> b \<in> B})"
1413 using insert by(simp add:inf_Sup1_distrib[OF B])
1414 also have "\<dots> = \<Squnion>\<^bsub>fin\<^esub>({inf x b |b. b \<in> B} \<union> {inf a b |a b. a \<in> A \<and> b \<in> B})"
1415 (is "_ = \<Squnion>\<^bsub>fin\<^esub>?M")
1417 by (simp add: Sup_fin_def fold1_Un2 [OF finB _ finAB ne])
1418 also have "?M = {inf a b |a b. a \<in> insert x A \<and> b \<in> B}"
1420 finally show ?case .
1425 context complete_lattice
1429 assumes "finite A" and "A \<noteq> {}"
1430 shows "\<Sqinter>\<^bsub>fin\<^esub>A = Inf A"
1432 interpret ab_semigroup_idem_mult inf
1433 by (rule ab_semigroup_idem_mult_inf)
1434 from `A \<noteq> {}` obtain b B where "A = {b} \<union> B" by auto
1435 moreover with `finite A` have "finite B" by simp
1436 ultimately show ?thesis
1437 by (simp add: Inf_fin_def fold1_eq_fold_idem inf_Inf_fold_inf [symmetric])
1441 assumes "finite A" and "A \<noteq> {}"
1442 shows "\<Squnion>\<^bsub>fin\<^esub>A = Sup A"
1444 interpret ab_semigroup_idem_mult sup
1445 by (rule ab_semigroup_idem_mult_sup)
1446 from `A \<noteq> {}` obtain b B where "A = {b} \<union> B" by auto
1447 moreover with `finite A` have "finite B" by simp
1448 ultimately show ?thesis
1449 by (simp add: Sup_fin_def fold1_eq_fold_idem sup_Sup_fold_sup [symmetric])
1455 subsection {* Versions of @{const min} and @{const max} on non-empty sets *}
1457 definition (in linorder) Min :: "'a set \<Rightarrow> 'a" where
1460 definition (in linorder) Max :: "'a set \<Rightarrow> 'a" where
1463 sublocale linorder < Min!: semilattice_big min Min proof
1464 qed (simp add: Min_def)
1466 sublocale linorder < Max!: semilattice_big max Max proof
1467 qed (simp add: Max_def)
1472 lemmas Min_singleton = Min.singleton
1473 lemmas Max_singleton = Max.singleton
1476 assumes "finite A" and "A \<noteq> {}"
1477 shows "Min (insert x A) = min x (Min A)"
1481 assumes "finite A" and "A \<noteq> {}"
1482 shows "Max (insert x A) = max x (Max A)"
1486 assumes "finite A" and "A \<noteq> {}" and "finite B" and "B \<noteq> {}"
1487 shows "Min (A \<union> B) = min (Min A) (Min B)"
1488 using assms by (rule Min.union_idem)
1491 assumes "finite A" and "A \<noteq> {}" and "finite B" and "B \<noteq> {}"
1492 shows "Max (A \<union> B) = max (Max A) (Max B)"
1493 using assms by (rule Max.union_idem)
1495 lemma hom_Min_commute:
1496 assumes "\<And>x y. h (min x y) = min (h x) (h y)"
1497 and "finite N" and "N \<noteq> {}"
1498 shows "h (Min N) = Min (h ` N)"
1499 using assms by (rule Min.hom_commute)
1501 lemma hom_Max_commute:
1502 assumes "\<And>x y. h (max x y) = max (h x) (h y)"
1503 and "finite N" and "N \<noteq> {}"
1504 shows "h (Max N) = Max (h ` N)"
1505 using assms by (rule Max.hom_commute)
1507 lemma ab_semigroup_idem_mult_min:
1508 "class.ab_semigroup_idem_mult min"
1509 proof qed (auto simp add: min_def)
1511 lemma ab_semigroup_idem_mult_max:
1512 "class.ab_semigroup_idem_mult max"
1513 proof qed (auto simp add: max_def)
1516 "class.semilattice_inf max (op \<ge>) (op >)"
1517 by (fact min_max.dual_semilattice)
1520 "ord.max (op \<ge>) = min"
1521 by (auto simp add: ord.max_def_raw min_def fun_eq_iff)
1524 "ord.min (op \<ge>) = max"
1525 by (auto simp add: ord.min_def_raw max_def fun_eq_iff)
1527 lemma strict_below_fold1_iff:
1528 assumes "finite A" and "A \<noteq> {}"
1529 shows "x < fold1 min A \<longleftrightarrow> (\<forall>a\<in>A. x < a)"
1531 interpret ab_semigroup_idem_mult min
1532 by (rule ab_semigroup_idem_mult_min)
1533 from assms show ?thesis
1534 by (induct rule: finite_ne_induct)
1535 (simp_all add: fold1_insert)
1538 lemma fold1_below_iff:
1539 assumes "finite A" and "A \<noteq> {}"
1540 shows "fold1 min A \<le> x \<longleftrightarrow> (\<exists>a\<in>A. a \<le> x)"
1542 interpret ab_semigroup_idem_mult min
1543 by (rule ab_semigroup_idem_mult_min)
1544 from assms show ?thesis
1545 by (induct rule: finite_ne_induct)
1546 (simp_all add: fold1_insert min_le_iff_disj)
1549 lemma fold1_strict_below_iff:
1550 assumes "finite A" and "A \<noteq> {}"
1551 shows "fold1 min A < x \<longleftrightarrow> (\<exists>a\<in>A. a < x)"
1553 interpret ab_semigroup_idem_mult min
1554 by (rule ab_semigroup_idem_mult_min)
1555 from assms show ?thesis
1556 by (induct rule: finite_ne_induct)
1557 (simp_all add: fold1_insert min_less_iff_disj)
1560 lemma fold1_antimono:
1561 assumes "A \<noteq> {}" and "A \<subseteq> B" and "finite B"
1562 shows "fold1 min B \<le> fold1 min A"
1564 assume "A = B" thus ?thesis by simp
1566 interpret ab_semigroup_idem_mult min
1567 by (rule ab_semigroup_idem_mult_min)
1568 assume neq: "A \<noteq> B"
1569 have B: "B = A \<union> (B-A)" using `A \<subseteq> B` by blast
1570 have "fold1 min B = fold1 min (A \<union> (B-A))" by(subst B)(rule refl)
1571 also have "\<dots> = min (fold1 min A) (fold1 min (B-A))"
1573 have "finite A" by(rule finite_subset[OF `A \<subseteq> B` `finite B`])
1574 moreover have "finite(B-A)" by(rule finite_Diff[OF `finite B`])
1575 moreover have "(B-A) \<noteq> {}" using assms neq by blast
1576 moreover have "A Int (B-A) = {}" using assms by blast
1577 ultimately show ?thesis using `A \<noteq> {}` by (rule_tac fold1_Un)
1579 also have "\<dots> \<le> fold1 min A" by (simp add: min_le_iff_disj)
1580 finally show ?thesis .
1583 lemma Min_in [simp]:
1584 assumes "finite A" and "A \<noteq> {}"
1585 shows "Min A \<in> A"
1587 interpret ab_semigroup_idem_mult min
1588 by (rule ab_semigroup_idem_mult_min)
1589 from assms fold1_in show ?thesis by (fastforce simp: Min_def min_def)
1592 lemma Max_in [simp]:
1593 assumes "finite A" and "A \<noteq> {}"
1594 shows "Max A \<in> A"
1596 interpret ab_semigroup_idem_mult max
1597 by (rule ab_semigroup_idem_mult_max)
1598 from assms fold1_in [of A] show ?thesis by (fastforce simp: Max_def max_def)
1601 lemma Min_le [simp]:
1602 assumes "finite A" and "x \<in> A"
1603 shows "Min A \<le> x"
1604 using assms by (simp add: Min_def min_max.fold1_belowI)
1606 lemma Max_ge [simp]:
1607 assumes "finite A" and "x \<in> A"
1608 shows "x \<le> Max A"
1609 by (simp add: Max_def semilattice_inf.fold1_belowI [OF max_lattice] assms)
1611 lemma Min_ge_iff [simp, no_atp]:
1612 assumes "finite A" and "A \<noteq> {}"
1613 shows "x \<le> Min A \<longleftrightarrow> (\<forall>a\<in>A. x \<le> a)"
1614 using assms by (simp add: Min_def min_max.below_fold1_iff)
1616 lemma Max_le_iff [simp, no_atp]:
1617 assumes "finite A" and "A \<noteq> {}"
1618 shows "Max A \<le> x \<longleftrightarrow> (\<forall>a\<in>A. a \<le> x)"
1619 by (simp add: Max_def semilattice_inf.below_fold1_iff [OF max_lattice] assms)
1621 lemma Min_gr_iff [simp, no_atp]:
1622 assumes "finite A" and "A \<noteq> {}"
1623 shows "x < Min A \<longleftrightarrow> (\<forall>a\<in>A. x < a)"
1624 using assms by (simp add: Min_def strict_below_fold1_iff)
1626 lemma Max_less_iff [simp, no_atp]:
1627 assumes "finite A" and "A \<noteq> {}"
1628 shows "Max A < x \<longleftrightarrow> (\<forall>a\<in>A. a < x)"
1629 by (simp add: Max_def linorder.dual_max [OF dual_linorder]
1630 linorder.strict_below_fold1_iff [OF dual_linorder] assms)
1632 lemma Min_le_iff [no_atp]:
1633 assumes "finite A" and "A \<noteq> {}"
1634 shows "Min A \<le> x \<longleftrightarrow> (\<exists>a\<in>A. a \<le> x)"
1635 using assms by (simp add: Min_def fold1_below_iff)
1637 lemma Max_ge_iff [no_atp]:
1638 assumes "finite A" and "A \<noteq> {}"
1639 shows "x \<le> Max A \<longleftrightarrow> (\<exists>a\<in>A. x \<le> a)"
1640 by (simp add: Max_def linorder.dual_max [OF dual_linorder]
1641 linorder.fold1_below_iff [OF dual_linorder] assms)
1643 lemma Min_less_iff [no_atp]:
1644 assumes "finite A" and "A \<noteq> {}"
1645 shows "Min A < x \<longleftrightarrow> (\<exists>a\<in>A. a < x)"
1646 using assms by (simp add: Min_def fold1_strict_below_iff)
1648 lemma Max_gr_iff [no_atp]:
1649 assumes "finite A" and "A \<noteq> {}"
1650 shows "x < Max A \<longleftrightarrow> (\<exists>a\<in>A. x < a)"
1651 by (simp add: Max_def linorder.dual_max [OF dual_linorder]
1652 linorder.fold1_strict_below_iff [OF dual_linorder] assms)
1656 assumes "\<And>y. y \<in> A \<Longrightarrow> y \<ge> x"
1659 proof (rule antisym)
1660 from `x \<in> A` have "A \<noteq> {}" by auto
1661 with assms show "Min A \<ge> x" by simp
1663 from assms show "x \<ge> Min A" by simp
1668 assumes "\<And>y. y \<in> A \<Longrightarrow> y \<le> x"
1671 proof (rule antisym)
1672 from `x \<in> A` have "A \<noteq> {}" by auto
1673 with assms show "Max A \<le> x" by simp
1675 from assms show "x \<le> Max A" by simp
1679 assumes "M \<subseteq> N" and "M \<noteq> {}" and "finite N"
1680 shows "Min N \<le> Min M"
1681 using assms by (simp add: Min_def fold1_antimono)
1684 assumes "M \<subseteq> N" and "M \<noteq> {}" and "finite N"
1685 shows "Max M \<le> Max N"
1686 by (simp add: Max_def linorder.dual_max [OF dual_linorder]
1687 linorder.fold1_antimono [OF dual_linorder] assms)
1689 lemma finite_linorder_max_induct[consumes 1, case_names empty insert]:
1690 assumes fin: "finite A"
1692 and insert: "(!!b A. finite A \<Longrightarrow> ALL a:A. a < b \<Longrightarrow> P A \<Longrightarrow> P(insert b A))"
1694 using fin empty insert
1695 proof (induct rule: finite_psubset_induct)
1697 have IH: "\<And>B. \<lbrakk>B < A; P {}; (\<And>A b. \<lbrakk>finite A; \<forall>a\<in>A. a<b; P A\<rbrakk> \<Longrightarrow> P (insert b A))\<rbrakk> \<Longrightarrow> P B" by fact
1698 have fin: "finite A" by fact
1699 have empty: "P {}" by fact
1700 have step: "\<And>b A. \<lbrakk>finite A; \<forall>a\<in>A. a < b; P A\<rbrakk> \<Longrightarrow> P (insert b A)" by fact
1702 proof (cases "A = {}")
1704 then show "P A" using `P {}` by simp
1706 let ?B = "A - {Max A}"
1707 let ?A = "insert (Max A) ?B"
1708 have "finite ?B" using `finite A` by simp
1709 assume "A \<noteq> {}"
1710 with `finite A` have "Max A : A" by auto
1711 then have A: "?A = A" using insert_Diff_single insert_absorb by auto
1712 then have "P ?B" using `P {}` step IH[of ?B] by blast
1714 have "\<forall>a\<in>?B. a < Max A" using Max_ge [OF `finite A`] by fastforce
1715 ultimately show "P A" using A insert_Diff_single step[OF `finite ?B`] by fastforce
1719 lemma finite_linorder_min_induct[consumes 1, case_names empty insert]:
1720 "\<lbrakk>finite A; P {}; \<And>b A. \<lbrakk>finite A; \<forall>a\<in>A. b < a; P A\<rbrakk> \<Longrightarrow> P (insert b A)\<rbrakk> \<Longrightarrow> P A"
1721 by(rule linorder.finite_linorder_max_induct[OF dual_linorder])
1725 context linordered_ab_semigroup_add
1728 lemma add_Min_commute:
1730 assumes "finite N" and "N \<noteq> {}"
1731 shows "k + Min N = Min {k + m | m. m \<in> N}"
1733 have "\<And>x y. k + min x y = min (k + x) (k + y)"
1734 by (simp add: min_def not_le)
1735 (blast intro: antisym less_imp_le add_left_mono)
1736 with assms show ?thesis
1737 using hom_Min_commute [of "plus k" N]
1738 by simp (blast intro: arg_cong [where f = Min])
1741 lemma add_Max_commute:
1743 assumes "finite N" and "N \<noteq> {}"
1744 shows "k + Max N = Max {k + m | m. m \<in> N}"
1746 have "\<And>x y. k + max x y = max (k + x) (k + y)"
1747 by (simp add: max_def not_le)
1748 (blast intro: antisym less_imp_le add_left_mono)
1749 with assms show ?thesis
1750 using hom_Max_commute [of "plus k" N]
1751 by simp (blast intro: arg_cong [where f = Max])
1756 context linordered_ab_group_add
1759 lemma minus_Max_eq_Min [simp]:
1760 "finite S \<Longrightarrow> S \<noteq> {} \<Longrightarrow> - (Max S) = Min (uminus ` S)"
1761 by (induct S rule: finite_ne_induct) (simp_all add: minus_max_eq_min)
1763 lemma minus_Min_eq_Max [simp]:
1764 "finite S \<Longrightarrow> S \<noteq> {} \<Longrightarrow> - (Min S) = Max (uminus ` S)"
1765 by (induct S rule: finite_ne_induct) (simp_all add: minus_min_eq_max)