src/HOL/Big_Operators.thy
author hoelzl
Fri Mar 22 10:41:43 2013 +0100 (2013-03-22)
changeset 51474 1e9e68247ad1
parent 51263 31e786e0e6a7
child 51489 f738e6dbd844
permissions -rw-r--r--
generalize Bfun and Bseq to metric spaces; Bseq is an abbreviation for Bfun
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(*  Title:      HOL/Big_Operators.thy
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    Author:     Tobias Nipkow, Lawrence C Paulson and Markus Wenzel
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                with contributions by Jeremy Avigad
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*)
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header {* Big operators and finite (non-empty) sets *}
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theory Big_Operators
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imports Finite_Set Metis
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begin
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subsection {* Generic monoid operation over a set *}
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no_notation times (infixl "*" 70)
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no_notation Groups.one ("1")
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locale comm_monoid_big = comm_monoid +
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  fixes F :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b set \<Rightarrow> 'a"
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  assumes F_eq: "F g A = (if finite A then fold_image (op *) g 1 A else 1)"
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sublocale comm_monoid_big < folding_image proof
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qed (simp add: F_eq)
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context comm_monoid_big
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begin
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lemma infinite [simp]:
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  "\<not> finite A \<Longrightarrow> F g A = 1"
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  by (simp add: F_eq)
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lemma F_cong:
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  assumes "A = B" "\<And>x. x \<in> B \<Longrightarrow> h x = g x"
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  shows "F h A = F g B"
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proof cases
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  assume "finite A"
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  with assms show ?thesis unfolding `A = B` by (simp cong: cong)
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next
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  assume "\<not> finite A"
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  then show ?thesis unfolding `A = B` by simp
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qed
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lemma strong_F_cong [cong]:
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  "\<lbrakk> A = B; !!x. x:B =simp=> g x = h x \<rbrakk>
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   \<Longrightarrow> F (%x. g x) A = F (%x. h x) B"
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by (rule F_cong) (simp_all add: simp_implies_def)
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lemma F_neutral[simp]: "F (%i. 1) A = 1"
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by (cases "finite A") (simp_all add: neutral)
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lemma F_neutral': "ALL a:A. g a = 1 \<Longrightarrow> F g A = 1"
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by simp
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lemma F_subset_diff: "\<lbrakk> B \<subseteq> A; finite A \<rbrakk> \<Longrightarrow> F g A = F g (A - B) * F g B"
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by (metis Diff_partition union_disjoint Diff_disjoint finite_Un inf_commute sup_commute)
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lemma F_mono_neutral_cong_left:
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  assumes "finite T" and "S \<subseteq> T" and "\<forall>i \<in> T - S. h i = 1"
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  and "\<And>x. x \<in> S \<Longrightarrow> g x = h x" shows "F g S = F h T"
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proof-
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  have eq: "T = S \<union> (T - S)" using `S \<subseteq> T` by blast
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  have d: "S \<inter> (T - S) = {}" using `S \<subseteq> T` by blast
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  from `finite T` `S \<subseteq> T` have f: "finite S" "finite (T - S)"
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    by (auto intro: finite_subset)
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  show ?thesis using assms(4)
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    by (simp add: union_disjoint[OF f d, unfolded eq[symmetric]] F_neutral'[OF assms(3)])
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qed
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lemma F_mono_neutral_cong_right:
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  "\<lbrakk> finite T; S \<subseteq> T; \<forall>i \<in> T - S. g i = 1; \<And>x. x \<in> S \<Longrightarrow> g x = h x \<rbrakk>
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   \<Longrightarrow> F g T = F h S"
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by(auto intro!: F_mono_neutral_cong_left[symmetric])
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lemma F_mono_neutral_left:
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  "\<lbrakk> finite T; S \<subseteq> T; \<forall>i \<in> T - S. g i = 1 \<rbrakk> \<Longrightarrow> F g S = F g T"
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by(blast intro: F_mono_neutral_cong_left)
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lemma F_mono_neutral_right:
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  "\<lbrakk> finite T;  S \<subseteq> T;  \<forall>i \<in> T - S. g i = 1 \<rbrakk> \<Longrightarrow> F g T = F g S"
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by(blast intro!: F_mono_neutral_left[symmetric])
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lemma F_delta: 
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  assumes fS: "finite S"
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  shows "F (\<lambda>k. if k=a then b k else 1) S = (if a \<in> S then b a else 1)"
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proof-
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  let ?f = "(\<lambda>k. if k=a then b k else 1)"
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  { assume a: "a \<notin> S"
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    hence "\<forall>k\<in>S. ?f k = 1" by simp
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    hence ?thesis  using a by simp }
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  moreover
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  { assume a: "a \<in> S"
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    let ?A = "S - {a}"
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    let ?B = "{a}"
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    have eq: "S = ?A \<union> ?B" using a by blast 
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    have dj: "?A \<inter> ?B = {}" by simp
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    from fS have fAB: "finite ?A" "finite ?B" by auto  
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    have "F ?f S = F ?f ?A * F ?f ?B"
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      using union_disjoint[OF fAB dj, of ?f, unfolded eq[symmetric]]
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      by simp
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    then have ?thesis  using a by simp }
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  ultimately show ?thesis by blast
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qed
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lemma F_delta': 
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  assumes fS: "finite S" shows 
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  "F (\<lambda>k. if a = k then b k else 1) S = (if a \<in> S then b a else 1)"
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using F_delta[OF fS, of a b, symmetric] by (auto intro: F_cong)
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lemma F_fun_f: "F (%x. g x * h x) A = (F g A * F h A)"
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by (cases "finite A") (simp_all add: distrib)
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text {* for ad-hoc proofs for @{const fold_image} *}
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lemma comm_monoid_mult:  "class.comm_monoid_mult (op *) 1"
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proof qed (auto intro: assoc commute)
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lemma F_Un_neutral:
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  assumes fS: "finite S" and fT: "finite T"
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  and I1: "\<forall>x \<in> S\<inter>T. g x = 1"
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  shows "F g (S \<union> T) = F g S  * F g T"
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proof -
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  interpret comm_monoid_mult "op *" 1 by (fact comm_monoid_mult)
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  show ?thesis
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  using fS fT
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  apply (simp add: F_eq)
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  apply (rule fold_image_Un_one)
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  using I1 by auto
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qed
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lemma If_cases:
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  fixes P :: "'b \<Rightarrow> bool" and g h :: "'b \<Rightarrow> 'a"
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  assumes fA: "finite A"
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  shows "F (\<lambda>x. if P x then h x else g x) A =
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         F h (A \<inter> {x. P x}) * F g (A \<inter> - {x. P x})"
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proof-
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  have a: "A = A \<inter> {x. P x} \<union> A \<inter> -{x. P x}" 
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          "(A \<inter> {x. P x}) \<inter> (A \<inter> -{x. P x}) = {}" 
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    by blast+
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  from fA 
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  have f: "finite (A \<inter> {x. P x})" "finite (A \<inter> -{x. P x})" by auto
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  let ?g = "\<lambda>x. if P x then h x else g x"
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  from union_disjoint[OF f a(2), of ?g] a(1)
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  show ?thesis
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    by (subst (1 2) F_cong) simp_all
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qed
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end
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text {* for ad-hoc proofs for @{const fold_image} *}
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lemma (in comm_monoid_add) comm_monoid_mult:
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  "class.comm_monoid_mult (op +) 0"
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proof qed (auto intro: add_assoc add_commute)
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notation times (infixl "*" 70)
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notation Groups.one ("1")
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subsection {* Generalized summation over a set *}
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definition (in comm_monoid_add) setsum :: "('b \<Rightarrow> 'a) => 'b set => 'a" where
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  "setsum f A = (if finite A then fold_image (op +) f 0 A else 0)"
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sublocale comm_monoid_add < setsum!: comm_monoid_big "op +" 0 setsum proof
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qed (fact setsum_def)
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abbreviation
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  Setsum  ("\<Sum>_" [1000] 999) where
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  "\<Sum>A == setsum (%x. x) A"
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text{* Now: lot's of fancy syntax. First, @{term "setsum (%x. e) A"} is
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written @{text"\<Sum>x\<in>A. e"}. *}
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syntax
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  "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add"    ("(3SUM _:_. _)" [0, 51, 10] 10)
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syntax (xsymbols)
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  "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add"    ("(3\<Sum>_\<in>_. _)" [0, 51, 10] 10)
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syntax (HTML output)
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  "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add"    ("(3\<Sum>_\<in>_. _)" [0, 51, 10] 10)
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translations -- {* Beware of argument permutation! *}
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  "SUM i:A. b" == "CONST setsum (%i. b) A"
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  "\<Sum>i\<in>A. b" == "CONST setsum (%i. b) A"
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text{* Instead of @{term"\<Sum>x\<in>{x. P}. e"} we introduce the shorter
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 @{text"\<Sum>x|P. e"}. *}
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syntax
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  "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3SUM _ |/ _./ _)" [0,0,10] 10)
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syntax (xsymbols)
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  "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Sum>_ | (_)./ _)" [0,0,10] 10)
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syntax (HTML output)
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  "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Sum>_ | (_)./ _)" [0,0,10] 10)
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translations
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  "SUM x|P. t" => "CONST setsum (%x. t) {x. P}"
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  "\<Sum>x|P. t" => "CONST setsum (%x. t) {x. P}"
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print_translation {*
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let
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  fun setsum_tr' [Abs (x, Tx, t), Const (@{const_syntax Collect}, _) $ Abs (y, Ty, P)] =
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        if x <> y then raise Match
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        else
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          let
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            val x' = Syntax_Trans.mark_bound_body (x, Tx);
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            val t' = subst_bound (x', t);
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            val P' = subst_bound (x', P);
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          in
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            Syntax.const @{syntax_const "_qsetsum"} $ Syntax_Trans.mark_bound_abs (x, Tx) $ P' $ t'
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          end
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    | setsum_tr' _ = raise Match;
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in [(@{const_syntax setsum}, setsum_tr')] end
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*}
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lemma setsum_empty:
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  "setsum f {} = 0"
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  by (fact setsum.empty)
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lemma setsum_insert:
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  "finite F ==> a \<notin> F ==> setsum f (insert a F) = f a + setsum f F"
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  by (fact setsum.insert)
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lemma setsum_infinite:
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  "~ finite A ==> setsum f A = 0"
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  by (fact setsum.infinite)
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lemma (in comm_monoid_add) setsum_reindex:
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  assumes "inj_on f B" shows "setsum h (f ` B) = setsum (h \<circ> f) B"
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proof -
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  interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
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  from assms show ?thesis by (auto simp add: setsum_def fold_image_reindex o_def dest!:finite_imageD)
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qed
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lemma setsum_reindex_id:
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  "inj_on f B ==> setsum f B = setsum id (f ` B)"
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by (simp add: setsum_reindex)
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lemma setsum_reindex_nonzero: 
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  assumes fS: "finite S"
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  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"
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  shows "setsum h (f ` S) = setsum (h o f) S"
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using nz
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proof(induct rule: finite_induct[OF fS])
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  case 1 thus ?case by simp
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next
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  case (2 x F) 
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  { assume fxF: "f x \<in> f ` F" hence "\<exists>y \<in> F . f y = f x" by auto
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    then obtain y where y: "y \<in> F" "f x = f y" by auto 
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    from "2.hyps" y have xy: "x \<noteq> y" by auto
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    from "2.prems"[of x y] "2.hyps" xy y have h0: "h (f x) = 0" by simp
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    have "setsum h (f ` insert x F) = setsum h (f ` F)" using fxF by auto
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    also have "\<dots> = setsum (h o f) (insert x F)" 
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      unfolding setsum.insert[OF `finite F` `x\<notin>F`]
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      using h0
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      apply (simp cong del:setsum.strong_F_cong)
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      apply (rule "2.hyps"(3))
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      apply (rule_tac y="y" in  "2.prems")
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      apply simp_all
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      done
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    finally have ?case . }
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  moreover
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  { assume fxF: "f x \<notin> f ` F"
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    have "setsum h (f ` insert x F) = h (f x) + setsum h (f ` F)" 
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      using fxF "2.hyps" by simp 
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    also have "\<dots> = setsum (h o f) (insert x F)"
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      unfolding setsum.insert[OF `finite F` `x\<notin>F`]
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      apply (simp cong del:setsum.strong_F_cong)
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      apply (rule cong [OF refl [of "op + (h (f x))"]])
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      apply (rule "2.hyps"(3))
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      apply (rule_tac y="y" in  "2.prems")
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      apply simp_all
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      done
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    finally have ?case . }
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  ultimately show ?case by blast
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qed
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lemma setsum_cong:
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  "A = B ==> (!!x. x:B ==> f x = g x) ==> setsum f A = setsum g B"
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by (fact setsum.F_cong)
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lemma strong_setsum_cong:
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  "A = B ==> (!!x. x:B =simp=> f x = g x)
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   ==> setsum (%x. f x) A = setsum (%x. g x) B"
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by (fact setsum.strong_F_cong)
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lemma setsum_cong2: "\<lbrakk>\<And>x. x \<in> A \<Longrightarrow> f x = g x\<rbrakk> \<Longrightarrow> setsum f A = setsum g A"
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by (auto intro: setsum_cong)
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lemma setsum_reindex_cong:
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   "[|inj_on f A; B = f ` A; !!a. a:A \<Longrightarrow> g a = h (f a)|] 
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    ==> setsum h B = setsum g A"
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by (simp add: setsum_reindex)
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lemmas setsum_0 = setsum.F_neutral
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lemmas setsum_0' = setsum.F_neutral'
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lemma setsum_Un_Int: "finite A ==> finite B ==>
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  setsum g (A Un B) + setsum g (A Int B) = setsum g A + setsum g B"
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  -- {* The reversed orientation looks more natural, but LOOPS as a simprule! *}
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by (fact setsum.union_inter)
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lemma setsum_Un_disjoint: "finite A ==> finite B
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  ==> A Int B = {} ==> setsum g (A Un B) = setsum g A + setsum g B"
nipkow@48849
   304
by (fact setsum.union_disjoint)
nipkow@48849
   305
nipkow@48849
   306
lemma setsum_subset_diff: "\<lbrakk> B \<subseteq> A; finite A \<rbrakk> \<Longrightarrow>
nipkow@48849
   307
    setsum f A = setsum f (A - B) + setsum f B"
nipkow@48849
   308
by(fact setsum.F_subset_diff)
nipkow@15402
   309
chaieb@29674
   310
lemma setsum_mono_zero_left: 
nipkow@48849
   311
  "\<lbrakk> finite T; S \<subseteq> T; \<forall>i \<in> T - S. f i = 0 \<rbrakk> \<Longrightarrow> setsum f S = setsum f T"
nipkow@48849
   312
by(fact setsum.F_mono_neutral_left)
chaieb@29674
   313
nipkow@48849
   314
lemmas setsum_mono_zero_right = setsum.F_mono_neutral_right
chaieb@29674
   315
chaieb@29674
   316
lemma setsum_mono_zero_cong_left: 
nipkow@48849
   317
  "\<lbrakk> finite T; S \<subseteq> T; \<forall>i \<in> T - S. g i = 0; \<And>x. x \<in> S \<Longrightarrow> f x = g x \<rbrakk>
nipkow@48849
   318
  \<Longrightarrow> setsum f S = setsum g T"
nipkow@48849
   319
by(fact setsum.F_mono_neutral_cong_left)
chaieb@29674
   320
nipkow@48849
   321
lemmas setsum_mono_zero_cong_right = setsum.F_mono_neutral_cong_right
chaieb@29674
   322
nipkow@48849
   323
lemma setsum_delta: "finite S \<Longrightarrow>
nipkow@48849
   324
  setsum (\<lambda>k. if k=a then b k else 0) S = (if a \<in> S then b a else 0)"
nipkow@48849
   325
by(fact setsum.F_delta)
nipkow@48849
   326
nipkow@48849
   327
lemma setsum_delta': "finite S \<Longrightarrow>
nipkow@48849
   328
  setsum (\<lambda>k. if a = k then b k else 0) S = (if a\<in> S then b a else 0)"
nipkow@48849
   329
by(fact setsum.F_delta')
chaieb@29674
   330
chaieb@30260
   331
lemma setsum_restrict_set:
chaieb@30260
   332
  assumes fA: "finite A"
chaieb@30260
   333
  shows "setsum f (A \<inter> B) = setsum (\<lambda>x. if x \<in> B then f x else 0) A"
chaieb@30260
   334
proof-
chaieb@30260
   335
  from fA have fab: "finite (A \<inter> B)" by auto
chaieb@30260
   336
  have aba: "A \<inter> B \<subseteq> A" by blast
chaieb@30260
   337
  let ?g = "\<lambda>x. if x \<in> A\<inter>B then f x else 0"
chaieb@30260
   338
  from setsum_mono_zero_left[OF fA aba, of ?g]
chaieb@30260
   339
  show ?thesis by simp
chaieb@30260
   340
qed
chaieb@30260
   341
chaieb@30260
   342
lemma setsum_cases:
chaieb@30260
   343
  assumes fA: "finite A"
hoelzl@35577
   344
  shows "setsum (\<lambda>x. if P x then f x else g x) A =
hoelzl@35577
   345
         setsum f (A \<inter> {x. P x}) + setsum g (A \<inter> - {x. P x})"
hoelzl@42986
   346
  using setsum.If_cases[OF fA] .
chaieb@29674
   347
paulson@15409
   348
(*But we can't get rid of finite I. If infinite, although the rhs is 0, 
paulson@15409
   349
  the lhs need not be, since UNION I A could still be finite.*)
haftmann@35816
   350
lemma (in comm_monoid_add) setsum_UN_disjoint:
haftmann@35816
   351
  assumes "finite I" and "ALL i:I. finite (A i)"
haftmann@35816
   352
    and "ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {}"
haftmann@35816
   353
  shows "setsum f (UNION I A) = (\<Sum>i\<in>I. setsum f (A i))"
haftmann@35816
   354
proof -
haftmann@35816
   355
  interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
wenzelm@41550
   356
  from assms show ?thesis by (simp add: setsum_def fold_image_UN_disjoint)
haftmann@35816
   357
qed
nipkow@15402
   358
paulson@15409
   359
text{*No need to assume that @{term C} is finite.  If infinite, the rhs is
paulson@15409
   360
directly 0, and @{term "Union C"} is also infinite, hence the lhs is also 0.*}
nipkow@15402
   361
lemma setsum_Union_disjoint:
hoelzl@44937
   362
  assumes "\<forall>A\<in>C. finite A" "\<forall>A\<in>C. \<forall>B\<in>C. A \<noteq> B \<longrightarrow> A Int B = {}"
hoelzl@44937
   363
  shows "setsum f (Union C) = setsum (setsum f) C"
hoelzl@44937
   364
proof cases
hoelzl@44937
   365
  assume "finite C"
hoelzl@44937
   366
  from setsum_UN_disjoint[OF this assms]
hoelzl@44937
   367
  show ?thesis
hoelzl@44937
   368
    by (simp add: SUP_def)
hoelzl@44937
   369
qed (force dest: finite_UnionD simp add: setsum_def)
nipkow@15402
   370
paulson@15409
   371
(*But we can't get rid of finite A. If infinite, although the lhs is 0, 
paulson@15409
   372
  the rhs need not be, since SIGMA A B could still be finite.*)
haftmann@35816
   373
lemma (in comm_monoid_add) setsum_Sigma:
haftmann@35816
   374
  assumes "finite A" and  "ALL x:A. finite (B x)"
haftmann@35816
   375
  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)"
haftmann@35816
   376
proof -
haftmann@35816
   377
  interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
wenzelm@41550
   378
  from assms show ?thesis by (simp add: setsum_def fold_image_Sigma split_def)
haftmann@35816
   379
qed
nipkow@15402
   380
paulson@15409
   381
text{*Here we can eliminate the finiteness assumptions, by cases.*}
paulson@15409
   382
lemma setsum_cartesian_product: 
paulson@17189
   383
   "(\<Sum>x\<in>A. (\<Sum>y\<in>B. f x y)) = (\<Sum>(x,y) \<in> A <*> B. f x y)"
paulson@15409
   384
apply (cases "finite A") 
paulson@15409
   385
 apply (cases "finite B") 
paulson@15409
   386
  apply (simp add: setsum_Sigma)
paulson@15409
   387
 apply (cases "A={}", simp)
nipkow@15543
   388
 apply (simp) 
paulson@15409
   389
apply (auto simp add: setsum_def
paulson@15409
   390
            dest: finite_cartesian_productD1 finite_cartesian_productD2) 
paulson@15409
   391
done
nipkow@15402
   392
nipkow@48861
   393
lemma setsum_addf: "setsum (%x. f x + g x) A = (setsum f A + setsum g A)"
nipkow@48861
   394
by (fact setsum.F_fun_f)
nipkow@15402
   395
nipkow@48893
   396
lemma setsum_Un_zero:  
nipkow@48893
   397
  "\<lbrakk> finite S; finite T; \<forall>x \<in> S\<inter>T. f x = 0 \<rbrakk> \<Longrightarrow>
nipkow@48893
   398
  setsum f (S \<union> T) = setsum f S + setsum f T"
nipkow@48893
   399
by(fact setsum.F_Un_neutral)
nipkow@48893
   400
nipkow@48893
   401
lemma setsum_UNION_zero: 
nipkow@48893
   402
  assumes fS: "finite S" and fSS: "\<forall>T \<in> S. finite T"
nipkow@48893
   403
  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"
nipkow@48893
   404
  shows "setsum f (\<Union>S) = setsum (\<lambda>T. setsum f T) S"
nipkow@48893
   405
  using fSS f0
nipkow@48893
   406
proof(induct rule: finite_induct[OF fS])
nipkow@48893
   407
  case 1 thus ?case by simp
nipkow@48893
   408
next
nipkow@48893
   409
  case (2 T F)
nipkow@48893
   410
  then have fTF: "finite T" "\<forall>T\<in>F. finite T" "finite F" and TF: "T \<notin> F" 
nipkow@48893
   411
    and H: "setsum f (\<Union> F) = setsum (setsum f) F" by auto
nipkow@48893
   412
  from fTF have fUF: "finite (\<Union>F)" by auto
nipkow@48893
   413
  from "2.prems" TF fTF
nipkow@48893
   414
  show ?case 
nipkow@48893
   415
    by (auto simp add: H[symmetric] intro: setsum_Un_zero[OF fTF(1) fUF, of f])
nipkow@48893
   416
qed
nipkow@48893
   417
nipkow@15402
   418
nipkow@15402
   419
subsubsection {* Properties in more restricted classes of structures *}
nipkow@15402
   420
nipkow@15402
   421
lemma setsum_SucD: "setsum f A = Suc n ==> EX a:A. 0 < f a"
nipkow@28853
   422
apply (case_tac "finite A")
nipkow@28853
   423
 prefer 2 apply (simp add: setsum_def)
nipkow@28853
   424
apply (erule rev_mp)
nipkow@28853
   425
apply (erule finite_induct, auto)
nipkow@28853
   426
done
nipkow@15402
   427
nipkow@15402
   428
lemma setsum_eq_0_iff [simp]:
nipkow@15402
   429
    "finite F ==> (setsum f F = 0) = (ALL a:F. f a = (0::nat))"
nipkow@28853
   430
by (induct set: finite) auto
nipkow@15402
   431
nipkow@30859
   432
lemma setsum_eq_Suc0_iff: "finite A \<Longrightarrow>
nipkow@30859
   433
  (setsum f A = Suc 0) = (EX a:A. f a = Suc 0 & (ALL b:A. a\<noteq>b \<longrightarrow> f b = 0))"
nipkow@30859
   434
apply(erule finite_induct)
nipkow@30859
   435
apply (auto simp add:add_is_1)
nipkow@30859
   436
done
nipkow@30859
   437
nipkow@30859
   438
lemmas setsum_eq_1_iff = setsum_eq_Suc0_iff[simplified One_nat_def[symmetric]]
nipkow@30859
   439
nipkow@15402
   440
lemma setsum_Un_nat: "finite A ==> finite B ==>
nipkow@28853
   441
  (setsum f (A Un B) :: nat) = setsum f A + setsum f B - setsum f (A Int B)"
nipkow@15402
   442
  -- {* For the natural numbers, we have subtraction. *}
nipkow@29667
   443
by (subst setsum_Un_Int [symmetric], auto simp add: algebra_simps)
nipkow@15402
   444
nipkow@15402
   445
lemma setsum_Un: "finite A ==> finite B ==>
nipkow@28853
   446
  (setsum f (A Un B) :: 'a :: ab_group_add) =
nipkow@28853
   447
   setsum f A + setsum f B - setsum f (A Int B)"
nipkow@29667
   448
by (subst setsum_Un_Int [symmetric], auto simp add: algebra_simps)
nipkow@15402
   449
haftmann@49715
   450
lemma setsum_Un2:
haftmann@49715
   451
  assumes "finite (A \<union> B)"
haftmann@49715
   452
  shows "setsum f (A \<union> B) = setsum f (A - B) + setsum f (B - A) + setsum f (A \<inter> B)"
haftmann@49715
   453
proof -
haftmann@49715
   454
  have "A \<union> B = A - B \<union> (B - A) \<union> A \<inter> B"
haftmann@49715
   455
    by auto
haftmann@49715
   456
  with assms show ?thesis by simp (subst setsum_Un_disjoint, auto)+
haftmann@49715
   457
qed
haftmann@49715
   458
haftmann@35816
   459
lemma (in comm_monoid_add) setsum_eq_general_reverses:
chaieb@30260
   460
  assumes fS: "finite S" and fT: "finite T"
chaieb@30260
   461
  and kh: "\<And>y. y \<in> T \<Longrightarrow> k y \<in> S \<and> h (k y) = y"
chaieb@30260
   462
  and hk: "\<And>x. x \<in> S \<Longrightarrow> h x \<in> T \<and> k (h x) = x \<and> g (h x) = f x"
chaieb@30260
   463
  shows "setsum f S = setsum g T"
haftmann@35816
   464
proof -
haftmann@35816
   465
  interpret comm_monoid_mult "op +" 0 by (fact comm_monoid_mult)
haftmann@35816
   466
  show ?thesis
chaieb@30260
   467
  apply (simp add: setsum_def fS fT)
haftmann@35816
   468
  apply (rule fold_image_eq_general_inverses)
haftmann@35816
   469
  apply (rule fS)
chaieb@30260
   470
  apply (erule kh)
chaieb@30260
   471
  apply (erule hk)
chaieb@30260
   472
  done
haftmann@35816
   473
qed
chaieb@30260
   474
nipkow@15402
   475
lemma setsum_diff1_nat: "(setsum f (A - {a}) :: nat) =
nipkow@28853
   476
  (if a:A then setsum f A - f a else setsum f A)"
nipkow@28853
   477
apply (case_tac "finite A")
nipkow@28853
   478
 prefer 2 apply (simp add: setsum_def)
nipkow@28853
   479
apply (erule finite_induct)
nipkow@28853
   480
 apply (auto simp add: insert_Diff_if)
nipkow@28853
   481
apply (drule_tac a = a in mk_disjoint_insert, auto)
nipkow@28853
   482
done
nipkow@15402
   483
nipkow@15402
   484
lemma setsum_diff1: "finite A \<Longrightarrow>
nipkow@15402
   485
  (setsum f (A - {a}) :: ('a::ab_group_add)) =
nipkow@15402
   486
  (if a:A then setsum f A - f a else setsum f A)"
nipkow@28853
   487
by (erule finite_induct) (auto simp add: insert_Diff_if)
nipkow@28853
   488
nipkow@28853
   489
lemma setsum_diff1'[rule_format]:
nipkow@28853
   490
  "finite A \<Longrightarrow> a \<in> A \<longrightarrow> (\<Sum> x \<in> A. f x) = f a + (\<Sum> x \<in> (A - {a}). f x)"
nipkow@28853
   491
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))"])
nipkow@28853
   492
apply (auto simp add: insert_Diff_if add_ac)
nipkow@28853
   493
done
obua@15552
   494
nipkow@31438
   495
lemma setsum_diff1_ring: assumes "finite A" "a \<in> A"
nipkow@31438
   496
  shows "setsum f (A - {a}) = setsum f A - (f a::'a::ring)"
nipkow@31438
   497
unfolding setsum_diff1'[OF assms] by auto
nipkow@31438
   498
nipkow@15402
   499
(* By Jeremy Siek: *)
nipkow@15402
   500
nipkow@15402
   501
lemma setsum_diff_nat: 
nipkow@28853
   502
assumes "finite B" and "B \<subseteq> A"
nipkow@28853
   503
shows "(setsum f (A - B) :: nat) = (setsum f A) - (setsum f B)"
nipkow@28853
   504
using assms
wenzelm@19535
   505
proof induct
nipkow@15402
   506
  show "setsum f (A - {}) = (setsum f A) - (setsum f {})" by simp
nipkow@15402
   507
next
nipkow@15402
   508
  fix F x assume finF: "finite F" and xnotinF: "x \<notin> F"
nipkow@15402
   509
    and xFinA: "insert x F \<subseteq> A"
nipkow@15402
   510
    and IH: "F \<subseteq> A \<Longrightarrow> setsum f (A - F) = setsum f A - setsum f F"
nipkow@15402
   511
  from xnotinF xFinA have xinAF: "x \<in> (A - F)" by simp
nipkow@15402
   512
  from xinAF have A: "setsum f ((A - F) - {x}) = setsum f (A - F) - f x"
nipkow@15402
   513
    by (simp add: setsum_diff1_nat)
nipkow@15402
   514
  from xFinA have "F \<subseteq> A" by simp
nipkow@15402
   515
  with IH have "setsum f (A - F) = setsum f A - setsum f F" by simp
nipkow@15402
   516
  with A have B: "setsum f ((A - F) - {x}) = setsum f A - setsum f F - f x"
nipkow@15402
   517
    by simp
nipkow@15402
   518
  from xnotinF have "A - insert x F = (A - F) - {x}" by auto
nipkow@15402
   519
  with B have C: "setsum f (A - insert x F) = setsum f A - setsum f F - f x"
nipkow@15402
   520
    by simp
nipkow@15402
   521
  from finF xnotinF have "setsum f (insert x F) = setsum f F + f x" by simp
nipkow@15402
   522
  with C have "setsum f (A - insert x F) = setsum f A - setsum f (insert x F)"
nipkow@15402
   523
    by simp
nipkow@15402
   524
  thus "setsum f (A - insert x F) = setsum f A - setsum f (insert x F)" by simp
nipkow@15402
   525
qed
nipkow@15402
   526
nipkow@15402
   527
lemma setsum_diff:
nipkow@15402
   528
  assumes le: "finite A" "B \<subseteq> A"
nipkow@15402
   529
  shows "setsum f (A - B) = setsum f A - ((setsum f B)::('a::ab_group_add))"
nipkow@15402
   530
proof -
nipkow@15402
   531
  from le have finiteB: "finite B" using finite_subset by auto
nipkow@15402
   532
  show ?thesis using finiteB le
wenzelm@21575
   533
  proof induct
wenzelm@19535
   534
    case empty
wenzelm@19535
   535
    thus ?case by auto
wenzelm@19535
   536
  next
wenzelm@19535
   537
    case (insert x F)
wenzelm@19535
   538
    thus ?case using le finiteB 
wenzelm@19535
   539
      by (simp add: Diff_insert[where a=x and B=F] setsum_diff1 insert_absorb)
nipkow@15402
   540
  qed
wenzelm@19535
   541
qed
nipkow@15402
   542
nipkow@15402
   543
lemma setsum_mono:
haftmann@35028
   544
  assumes le: "\<And>i. i\<in>K \<Longrightarrow> f (i::'a) \<le> ((g i)::('b::{comm_monoid_add, ordered_ab_semigroup_add}))"
nipkow@15402
   545
  shows "(\<Sum>i\<in>K. f i) \<le> (\<Sum>i\<in>K. g i)"
nipkow@15402
   546
proof (cases "finite K")
nipkow@15402
   547
  case True
nipkow@15402
   548
  thus ?thesis using le
wenzelm@19535
   549
  proof induct
nipkow@15402
   550
    case empty
nipkow@15402
   551
    thus ?case by simp
nipkow@15402
   552
  next
nipkow@15402
   553
    case insert
nipkow@44890
   554
    thus ?case using add_mono by fastforce
nipkow@15402
   555
  qed
nipkow@15402
   556
next
nipkow@15402
   557
  case False
nipkow@15402
   558
  thus ?thesis
nipkow@15402
   559
    by (simp add: setsum_def)
nipkow@15402
   560
qed
nipkow@15402
   561
nipkow@15554
   562
lemma setsum_strict_mono:
haftmann@35028
   563
  fixes f :: "'a \<Rightarrow> 'b::{ordered_cancel_ab_semigroup_add,comm_monoid_add}"
wenzelm@19535
   564
  assumes "finite A"  "A \<noteq> {}"
wenzelm@19535
   565
    and "!!x. x:A \<Longrightarrow> f x < g x"
wenzelm@19535
   566
  shows "setsum f A < setsum g A"
wenzelm@41550
   567
  using assms
nipkow@15554
   568
proof (induct rule: finite_ne_induct)
nipkow@15554
   569
  case singleton thus ?case by simp
nipkow@15554
   570
next
nipkow@15554
   571
  case insert thus ?case by (auto simp: add_strict_mono)
nipkow@15554
   572
qed
nipkow@15554
   573
nipkow@46699
   574
lemma setsum_strict_mono_ex1:
nipkow@46699
   575
fixes f :: "'a \<Rightarrow> 'b::{comm_monoid_add, ordered_cancel_ab_semigroup_add}"
nipkow@46699
   576
assumes "finite A" and "ALL x:A. f x \<le> g x" and "EX a:A. f a < g a"
nipkow@46699
   577
shows "setsum f A < setsum g A"
nipkow@46699
   578
proof-
nipkow@46699
   579
  from assms(3) obtain a where a: "a:A" "f a < g a" by blast
nipkow@46699
   580
  have "setsum f A = setsum f ((A-{a}) \<union> {a})"
nipkow@46699
   581
    by(simp add:insert_absorb[OF `a:A`])
nipkow@46699
   582
  also have "\<dots> = setsum f (A-{a}) + setsum f {a}"
nipkow@46699
   583
    using `finite A` by(subst setsum_Un_disjoint) auto
nipkow@46699
   584
  also have "setsum f (A-{a}) \<le> setsum g (A-{a})"
nipkow@46699
   585
    by(rule setsum_mono)(simp add: assms(2))
nipkow@46699
   586
  also have "setsum f {a} < setsum g {a}" using a by simp
nipkow@46699
   587
  also have "setsum g (A - {a}) + setsum g {a} = setsum g((A-{a}) \<union> {a})"
nipkow@46699
   588
    using `finite A` by(subst setsum_Un_disjoint[symmetric]) auto
nipkow@46699
   589
  also have "\<dots> = setsum g A" by(simp add:insert_absorb[OF `a:A`])
nipkow@46699
   590
  finally show ?thesis by (metis add_right_mono add_strict_left_mono)
nipkow@46699
   591
qed
nipkow@46699
   592
nipkow@15535
   593
lemma setsum_negf:
wenzelm@19535
   594
  "setsum (%x. - (f x)::'a::ab_group_add) A = - setsum f A"
nipkow@15535
   595
proof (cases "finite A")
berghofe@22262
   596
  case True thus ?thesis by (induct set: finite) auto
nipkow@15535
   597
next
nipkow@15535
   598
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
   599
qed
nipkow@15402
   600
nipkow@15535
   601
lemma setsum_subtractf:
wenzelm@19535
   602
  "setsum (%x. ((f x)::'a::ab_group_add) - g x) A =
wenzelm@19535
   603
    setsum f A - setsum g A"
nipkow@15535
   604
proof (cases "finite A")
nipkow@15535
   605
  case True thus ?thesis by (simp add: diff_minus setsum_addf setsum_negf)
nipkow@15535
   606
next
nipkow@15535
   607
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
   608
qed
nipkow@15402
   609
nipkow@15535
   610
lemma setsum_nonneg:
haftmann@35028
   611
  assumes nn: "\<forall>x\<in>A. (0::'a::{ordered_ab_semigroup_add,comm_monoid_add}) \<le> f x"
wenzelm@19535
   612
  shows "0 \<le> setsum f A"
nipkow@15535
   613
proof (cases "finite A")
nipkow@15535
   614
  case True thus ?thesis using nn
wenzelm@21575
   615
  proof induct
wenzelm@19535
   616
    case empty then show ?case by simp
wenzelm@19535
   617
  next
wenzelm@19535
   618
    case (insert x F)
wenzelm@19535
   619
    then have "0 + 0 \<le> f x + setsum f F" by (blast intro: add_mono)
wenzelm@19535
   620
    with insert show ?case by simp
wenzelm@19535
   621
  qed
nipkow@15535
   622
next
nipkow@15535
   623
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
   624
qed
nipkow@15402
   625
nipkow@15535
   626
lemma setsum_nonpos:
haftmann@35028
   627
  assumes np: "\<forall>x\<in>A. f x \<le> (0::'a::{ordered_ab_semigroup_add,comm_monoid_add})"
wenzelm@19535
   628
  shows "setsum f A \<le> 0"
nipkow@15535
   629
proof (cases "finite A")
nipkow@15535
   630
  case True thus ?thesis using np
wenzelm@21575
   631
  proof induct
wenzelm@19535
   632
    case empty then show ?case by simp
wenzelm@19535
   633
  next
wenzelm@19535
   634
    case (insert x F)
wenzelm@19535
   635
    then have "f x + setsum f F \<le> 0 + 0" by (blast intro: add_mono)
wenzelm@19535
   636
    with insert show ?case by simp
wenzelm@19535
   637
  qed
nipkow@15535
   638
next
nipkow@15535
   639
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
   640
qed
nipkow@15402
   641
hoelzl@36622
   642
lemma setsum_nonneg_leq_bound:
hoelzl@36622
   643
  fixes f :: "'a \<Rightarrow> 'b::{ordered_ab_group_add}"
hoelzl@36622
   644
  assumes "finite s" "\<And>i. i \<in> s \<Longrightarrow> f i \<ge> 0" "(\<Sum>i \<in> s. f i) = B" "i \<in> s"
hoelzl@36622
   645
  shows "f i \<le> B"
hoelzl@36622
   646
proof -
hoelzl@36622
   647
  have "0 \<le> (\<Sum> i \<in> s - {i}. f i)" and "0 \<le> f i"
hoelzl@36622
   648
    using assms by (auto intro!: setsum_nonneg)
hoelzl@36622
   649
  moreover
hoelzl@36622
   650
  have "(\<Sum> i \<in> s - {i}. f i) + f i = B"
hoelzl@36622
   651
    using assms by (simp add: setsum_diff1)
hoelzl@36622
   652
  ultimately show ?thesis by auto
hoelzl@36622
   653
qed
hoelzl@36622
   654
hoelzl@36622
   655
lemma setsum_nonneg_0:
hoelzl@36622
   656
  fixes f :: "'a \<Rightarrow> 'b::{ordered_ab_group_add}"
hoelzl@36622
   657
  assumes "finite s" and pos: "\<And> i. i \<in> s \<Longrightarrow> f i \<ge> 0"
hoelzl@36622
   658
  and "(\<Sum> i \<in> s. f i) = 0" and i: "i \<in> s"
hoelzl@36622
   659
  shows "f i = 0"
hoelzl@36622
   660
  using setsum_nonneg_leq_bound[OF assms] pos[OF i] by auto
hoelzl@36622
   661
nipkow@15539
   662
lemma setsum_mono2:
haftmann@36303
   663
fixes f :: "'a \<Rightarrow> 'b :: ordered_comm_monoid_add"
nipkow@15539
   664
assumes fin: "finite B" and sub: "A \<subseteq> B" and nn: "\<And>b. b \<in> B-A \<Longrightarrow> 0 \<le> f b"
nipkow@15539
   665
shows "setsum f A \<le> setsum f B"
nipkow@15539
   666
proof -
nipkow@15539
   667
  have "setsum f A \<le> setsum f A + setsum f (B-A)"
nipkow@15539
   668
    by(simp add: add_increasing2[OF setsum_nonneg] nn Ball_def)
nipkow@15539
   669
  also have "\<dots> = setsum f (A \<union> (B-A))" using fin finite_subset[OF sub fin]
nipkow@15539
   670
    by (simp add:setsum_Un_disjoint del:Un_Diff_cancel)
nipkow@15539
   671
  also have "A \<union> (B-A) = B" using sub by blast
nipkow@15539
   672
  finally show ?thesis .
nipkow@15539
   673
qed
nipkow@15542
   674
avigad@16775
   675
lemma setsum_mono3: "finite B ==> A <= B ==> 
avigad@16775
   676
    ALL x: B - A. 
haftmann@35028
   677
      0 <= ((f x)::'a::{comm_monoid_add,ordered_ab_semigroup_add}) ==>
avigad@16775
   678
        setsum f A <= setsum f B"
avigad@16775
   679
  apply (subgoal_tac "setsum f B = setsum f A + setsum f (B - A)")
avigad@16775
   680
  apply (erule ssubst)
avigad@16775
   681
  apply (subgoal_tac "setsum f A + 0 <= setsum f A + setsum f (B - A)")
avigad@16775
   682
  apply simp
avigad@16775
   683
  apply (rule add_left_mono)
avigad@16775
   684
  apply (erule setsum_nonneg)
avigad@16775
   685
  apply (subst setsum_Un_disjoint [THEN sym])
avigad@16775
   686
  apply (erule finite_subset, assumption)
avigad@16775
   687
  apply (rule finite_subset)
avigad@16775
   688
  prefer 2
avigad@16775
   689
  apply assumption
haftmann@32698
   690
  apply (auto simp add: sup_absorb2)
avigad@16775
   691
done
avigad@16775
   692
ballarin@19279
   693
lemma setsum_right_distrib: 
huffman@22934
   694
  fixes f :: "'a => ('b::semiring_0)"
nipkow@15402
   695
  shows "r * setsum f A = setsum (%n. r * f n) A"
nipkow@15402
   696
proof (cases "finite A")
nipkow@15402
   697
  case True
nipkow@15402
   698
  thus ?thesis
wenzelm@21575
   699
  proof induct
nipkow@15402
   700
    case empty thus ?case by simp
nipkow@15402
   701
  next
webertj@49962
   702
    case (insert x A) thus ?case by (simp add: distrib_left)
nipkow@15402
   703
  qed
nipkow@15402
   704
next
nipkow@15402
   705
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15402
   706
qed
nipkow@15402
   707
ballarin@17149
   708
lemma setsum_left_distrib:
huffman@22934
   709
  "setsum f A * (r::'a::semiring_0) = (\<Sum>n\<in>A. f n * r)"
ballarin@17149
   710
proof (cases "finite A")
ballarin@17149
   711
  case True
ballarin@17149
   712
  then show ?thesis
ballarin@17149
   713
  proof induct
ballarin@17149
   714
    case empty thus ?case by simp
ballarin@17149
   715
  next
webertj@49962
   716
    case (insert x A) thus ?case by (simp add: distrib_right)
ballarin@17149
   717
  qed
ballarin@17149
   718
next
ballarin@17149
   719
  case False thus ?thesis by (simp add: setsum_def)
ballarin@17149
   720
qed
ballarin@17149
   721
ballarin@17149
   722
lemma setsum_divide_distrib:
ballarin@17149
   723
  "setsum f A / (r::'a::field) = (\<Sum>n\<in>A. f n / r)"
ballarin@17149
   724
proof (cases "finite A")
ballarin@17149
   725
  case True
ballarin@17149
   726
  then show ?thesis
ballarin@17149
   727
  proof induct
ballarin@17149
   728
    case empty thus ?case by simp
ballarin@17149
   729
  next
ballarin@17149
   730
    case (insert x A) thus ?case by (simp add: add_divide_distrib)
ballarin@17149
   731
  qed
ballarin@17149
   732
next
ballarin@17149
   733
  case False thus ?thesis by (simp add: setsum_def)
ballarin@17149
   734
qed
ballarin@17149
   735
nipkow@15535
   736
lemma setsum_abs[iff]: 
haftmann@35028
   737
  fixes f :: "'a => ('b::ordered_ab_group_add_abs)"
nipkow@15402
   738
  shows "abs (setsum f A) \<le> setsum (%i. abs(f i)) A"
nipkow@15535
   739
proof (cases "finite A")
nipkow@15535
   740
  case True
nipkow@15535
   741
  thus ?thesis
wenzelm@21575
   742
  proof induct
nipkow@15535
   743
    case empty thus ?case by simp
nipkow@15535
   744
  next
nipkow@15535
   745
    case (insert x A)
nipkow@15535
   746
    thus ?case by (auto intro: abs_triangle_ineq order_trans)
nipkow@15535
   747
  qed
nipkow@15402
   748
next
nipkow@15535
   749
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15402
   750
qed
nipkow@15402
   751
nipkow@15535
   752
lemma setsum_abs_ge_zero[iff]: 
haftmann@35028
   753
  fixes f :: "'a => ('b::ordered_ab_group_add_abs)"
nipkow@15402
   754
  shows "0 \<le> setsum (%i. abs(f i)) A"
nipkow@15535
   755
proof (cases "finite A")
nipkow@15535
   756
  case True
nipkow@15535
   757
  thus ?thesis
wenzelm@21575
   758
  proof induct
nipkow@15535
   759
    case empty thus ?case by simp
nipkow@15535
   760
  next
huffman@36977
   761
    case (insert x A) thus ?case by auto
nipkow@15535
   762
  qed
nipkow@15402
   763
next
nipkow@15535
   764
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15402
   765
qed
nipkow@15402
   766
nipkow@15539
   767
lemma abs_setsum_abs[simp]: 
haftmann@35028
   768
  fixes f :: "'a => ('b::ordered_ab_group_add_abs)"
nipkow@15539
   769
  shows "abs (\<Sum>a\<in>A. abs(f a)) = (\<Sum>a\<in>A. abs(f a))"
nipkow@15539
   770
proof (cases "finite A")
nipkow@15539
   771
  case True
nipkow@15539
   772
  thus ?thesis
wenzelm@21575
   773
  proof induct
nipkow@15539
   774
    case empty thus ?case by simp
nipkow@15539
   775
  next
nipkow@15539
   776
    case (insert a A)
nipkow@15539
   777
    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
nipkow@15539
   778
    also have "\<dots> = \<bar>\<bar>f a\<bar> + \<bar>\<Sum>a\<in>A. \<bar>f a\<bar>\<bar>\<bar>"  using insert by simp
avigad@16775
   779
    also have "\<dots> = \<bar>f a\<bar> + \<bar>\<Sum>a\<in>A. \<bar>f a\<bar>\<bar>"
avigad@16775
   780
      by (simp del: abs_of_nonneg)
nipkow@15539
   781
    also have "\<dots> = (\<Sum>a\<in>insert a A. \<bar>f a\<bar>)" using insert by simp
nipkow@15539
   782
    finally show ?case .
nipkow@15539
   783
  qed
nipkow@15539
   784
next
nipkow@15539
   785
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15539
   786
qed
nipkow@15539
   787
nipkow@31080
   788
lemma setsum_Plus:
nipkow@31080
   789
  fixes A :: "'a set" and B :: "'b set"
nipkow@31080
   790
  assumes fin: "finite A" "finite B"
nipkow@31080
   791
  shows "setsum f (A <+> B) = setsum (f \<circ> Inl) A + setsum (f \<circ> Inr) B"
nipkow@31080
   792
proof -
nipkow@31080
   793
  have "A <+> B = Inl ` A \<union> Inr ` B" by auto
nipkow@31080
   794
  moreover from fin have "finite (Inl ` A :: ('a + 'b) set)" "finite (Inr ` B :: ('a + 'b) set)"
nipkow@40786
   795
    by auto
nipkow@31080
   796
  moreover have "Inl ` A \<inter> Inr ` B = ({} :: ('a + 'b) set)" by auto
nipkow@31080
   797
  moreover have "inj_on (Inl :: 'a \<Rightarrow> 'a + 'b) A" "inj_on (Inr :: 'b \<Rightarrow> 'a + 'b) B" by(auto intro: inj_onI)
nipkow@31080
   798
  ultimately show ?thesis using fin by(simp add: setsum_Un_disjoint setsum_reindex)
nipkow@31080
   799
qed
nipkow@31080
   800
nipkow@31080
   801
ballarin@17149
   802
text {* Commuting outer and inner summation *}
ballarin@17149
   803
ballarin@17149
   804
lemma setsum_commute:
ballarin@17149
   805
  "(\<Sum>i\<in>A. \<Sum>j\<in>B. f i j) = (\<Sum>j\<in>B. \<Sum>i\<in>A. f i j)"
ballarin@17149
   806
proof (simp add: setsum_cartesian_product)
paulson@17189
   807
  have "(\<Sum>(x,y) \<in> A <*> B. f x y) =
paulson@17189
   808
    (\<Sum>(y,x) \<in> (%(i, j). (j, i)) ` (A \<times> B). f x y)"
ballarin@17149
   809
    (is "?s = _")
ballarin@17149
   810
    apply (simp add: setsum_reindex [where f = "%(i, j). (j, i)"] swap_inj_on)
ballarin@17149
   811
    apply (simp add: split_def)
ballarin@17149
   812
    done
paulson@17189
   813
  also have "... = (\<Sum>(y,x)\<in>B \<times> A. f x y)"
ballarin@17149
   814
    (is "_ = ?t")
ballarin@17149
   815
    apply (simp add: swap_product)
ballarin@17149
   816
    done
ballarin@17149
   817
  finally show "?s = ?t" .
ballarin@17149
   818
qed
ballarin@17149
   819
ballarin@19279
   820
lemma setsum_product:
huffman@22934
   821
  fixes f :: "'a => ('b::semiring_0)"
ballarin@19279
   822
  shows "setsum f A * setsum g B = (\<Sum>i\<in>A. \<Sum>j\<in>B. f i * g j)"
ballarin@19279
   823
  by (simp add: setsum_right_distrib setsum_left_distrib) (rule setsum_commute)
ballarin@19279
   824
nipkow@34223
   825
lemma setsum_mult_setsum_if_inj:
nipkow@34223
   826
fixes f :: "'a => ('b::semiring_0)"
nipkow@34223
   827
shows "inj_on (%(a,b). f a * g b) (A \<times> B) ==>
nipkow@34223
   828
  setsum f A * setsum g B = setsum id {f a * g b|a b. a:A & b:B}"
nipkow@34223
   829
by(auto simp: setsum_product setsum_cartesian_product
nipkow@34223
   830
        intro!:  setsum_reindex_cong[symmetric])
nipkow@34223
   831
haftmann@35722
   832
lemma setsum_constant [simp]: "(\<Sum>x \<in> A. y) = of_nat(card A) * y"
haftmann@35722
   833
apply (cases "finite A")
haftmann@35722
   834
apply (erule finite_induct)
haftmann@35722
   835
apply (auto simp add: algebra_simps)
haftmann@35722
   836
done
haftmann@35722
   837
haftmann@35722
   838
lemma setsum_bounded:
haftmann@35722
   839
  assumes le: "\<And>i. i\<in>A \<Longrightarrow> f i \<le> (K::'a::{semiring_1, ordered_ab_semigroup_add})"
haftmann@35722
   840
  shows "setsum f A \<le> of_nat(card A) * K"
haftmann@35722
   841
proof (cases "finite A")
haftmann@35722
   842
  case True
haftmann@35722
   843
  thus ?thesis using le setsum_mono[where K=A and g = "%x. K"] by simp
haftmann@35722
   844
next
haftmann@35722
   845
  case False thus ?thesis by (simp add: setsum_def)
haftmann@35722
   846
qed
haftmann@35722
   847
haftmann@35722
   848
haftmann@35722
   849
subsubsection {* Cardinality as special case of @{const setsum} *}
haftmann@35722
   850
haftmann@35722
   851
lemma card_eq_setsum:
haftmann@35722
   852
  "card A = setsum (\<lambda>x. 1) A"
haftmann@35722
   853
  by (simp only: card_def setsum_def)
haftmann@35722
   854
haftmann@35722
   855
lemma card_UN_disjoint:
haftmann@46629
   856
  assumes "finite I" and "\<forall>i\<in>I. finite (A i)"
haftmann@46629
   857
    and "\<forall>i\<in>I. \<forall>j\<in>I. i \<noteq> j \<longrightarrow> A i \<inter> A j = {}"
haftmann@46629
   858
  shows "card (UNION I A) = (\<Sum>i\<in>I. card(A i))"
haftmann@46629
   859
proof -
haftmann@46629
   860
  have "(\<Sum>i\<in>I. card (A i)) = (\<Sum>i\<in>I. \<Sum>x\<in>A i. 1)" by simp
haftmann@46629
   861
  with assms show ?thesis by (simp add: card_eq_setsum setsum_UN_disjoint del: setsum_constant)
haftmann@46629
   862
qed
haftmann@35722
   863
haftmann@35722
   864
lemma card_Union_disjoint:
haftmann@35722
   865
  "finite C ==> (ALL A:C. finite A) ==>
haftmann@35722
   866
   (ALL A:C. ALL B:C. A \<noteq> B --> A Int B = {})
haftmann@35722
   867
   ==> card (Union C) = setsum card C"
haftmann@35722
   868
apply (frule card_UN_disjoint [of C id])
hoelzl@44937
   869
apply (simp_all add: SUP_def id_def)
haftmann@35722
   870
done
haftmann@35722
   871
haftmann@35722
   872
text{*The image of a finite set can be expressed using @{term fold_image}.*}
haftmann@35722
   873
lemma image_eq_fold_image:
haftmann@35722
   874
  "finite A ==> f ` A = fold_image (op Un) (%x. {f x}) {} A"
haftmann@35722
   875
proof (induct rule: finite_induct)
haftmann@35722
   876
  case empty then show ?case by simp
haftmann@35722
   877
next
haftmann@35722
   878
  interpret ab_semigroup_mult "op Un"
haftmann@35722
   879
    proof qed auto
haftmann@35722
   880
  case insert 
haftmann@35722
   881
  then show ?case by simp
haftmann@35722
   882
qed
haftmann@35722
   883
haftmann@35722
   884
subsubsection {* Cardinality of products *}
haftmann@35722
   885
haftmann@35722
   886
lemma card_SigmaI [simp]:
haftmann@35722
   887
  "\<lbrakk> finite A; ALL a:A. finite (B a) \<rbrakk>
haftmann@35722
   888
  \<Longrightarrow> card (SIGMA x: A. B x) = (\<Sum>a\<in>A. card (B a))"
haftmann@35722
   889
by(simp add: card_eq_setsum setsum_Sigma del:setsum_constant)
haftmann@35722
   890
haftmann@35722
   891
(*
haftmann@35722
   892
lemma SigmaI_insert: "y \<notin> A ==>
haftmann@35722
   893
  (SIGMA x:(insert y A). B x) = (({y} <*> (B y)) \<union> (SIGMA x: A. B x))"
haftmann@35722
   894
  by auto
haftmann@35722
   895
*)
haftmann@35722
   896
haftmann@35722
   897
lemma card_cartesian_product: "card (A <*> B) = card(A) * card(B)"
haftmann@35722
   898
  by (cases "finite A \<and> finite B")
haftmann@35722
   899
    (auto simp add: card_eq_0_iff dest: finite_cartesian_productD1 finite_cartesian_productD2)
haftmann@35722
   900
haftmann@35722
   901
lemma card_cartesian_product_singleton:  "card({x} <*> A) = card(A)"
haftmann@35722
   902
by (simp add: card_cartesian_product)
haftmann@35722
   903
ballarin@17149
   904
nipkow@15402
   905
subsection {* Generalized product over a set *}
nipkow@15402
   906
haftmann@35816
   907
definition (in comm_monoid_mult) setprod :: "('b \<Rightarrow> 'a) => 'b set => 'a" where
haftmann@35816
   908
  "setprod f A = (if finite A then fold_image (op *) f 1 A else 1)"
haftmann@35816
   909
huffman@35938
   910
sublocale comm_monoid_mult < setprod!: comm_monoid_big "op *" 1 setprod proof
haftmann@35816
   911
qed (fact setprod_def)
nipkow@15402
   912
wenzelm@19535
   913
abbreviation
wenzelm@21404
   914
  Setprod  ("\<Prod>_" [1000] 999) where
wenzelm@19535
   915
  "\<Prod>A == setprod (%x. x) A"
wenzelm@19535
   916
nipkow@15402
   917
syntax
paulson@17189
   918
  "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult"  ("(3PROD _:_. _)" [0, 51, 10] 10)
nipkow@15402
   919
syntax (xsymbols)
paulson@17189
   920
  "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult"  ("(3\<Prod>_\<in>_. _)" [0, 51, 10] 10)
nipkow@15402
   921
syntax (HTML output)
paulson@17189
   922
  "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult"  ("(3\<Prod>_\<in>_. _)" [0, 51, 10] 10)
nipkow@16550
   923
nipkow@16550
   924
translations -- {* Beware of argument permutation! *}
nipkow@28853
   925
  "PROD i:A. b" == "CONST setprod (%i. b) A" 
nipkow@28853
   926
  "\<Prod>i\<in>A. b" == "CONST setprod (%i. b) A" 
nipkow@16550
   927
nipkow@16550
   928
text{* Instead of @{term"\<Prod>x\<in>{x. P}. e"} we introduce the shorter
nipkow@16550
   929
 @{text"\<Prod>x|P. e"}. *}
nipkow@16550
   930
nipkow@16550
   931
syntax
paulson@17189
   932
  "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3PROD _ |/ _./ _)" [0,0,10] 10)
nipkow@16550
   933
syntax (xsymbols)
paulson@17189
   934
  "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Prod>_ | (_)./ _)" [0,0,10] 10)
nipkow@16550
   935
syntax (HTML output)
paulson@17189
   936
  "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Prod>_ | (_)./ _)" [0,0,10] 10)
nipkow@16550
   937
nipkow@15402
   938
translations
nipkow@28853
   939
  "PROD x|P. t" => "CONST setprod (%x. t) {x. P}"
nipkow@28853
   940
  "\<Prod>x|P. t" => "CONST setprod (%x. t) {x. P}"
nipkow@16550
   941
haftmann@35816
   942
lemma setprod_empty: "setprod f {} = 1"
haftmann@35816
   943
  by (fact setprod.empty)
nipkow@15402
   944
haftmann@35816
   945
lemma setprod_insert: "[| finite A; a \<notin> A |] ==>
nipkow@15402
   946
    setprod f (insert a A) = f a * setprod f A"
haftmann@35816
   947
  by (fact setprod.insert)
nipkow@15402
   948
haftmann@35816
   949
lemma setprod_infinite: "~ finite A ==> setprod f A = 1"
haftmann@35816
   950
  by (fact setprod.infinite)
paulson@15409
   951
nipkow@15402
   952
lemma setprod_reindex:
nipkow@28853
   953
   "inj_on f B ==> setprod h (f ` B) = setprod (h \<circ> f) B"
nipkow@48849
   954
by(auto simp: setprod_def fold_image_reindex o_def dest!:finite_imageD)
nipkow@15402
   955
nipkow@15402
   956
lemma setprod_reindex_id: "inj_on f B ==> setprod f B = setprod id (f ` B)"
nipkow@15402
   957
by (auto simp add: setprod_reindex)
nipkow@15402
   958
nipkow@15402
   959
lemma setprod_cong:
nipkow@15402
   960
  "A = B ==> (!!x. x:B ==> f x = g x) ==> setprod f A = setprod g B"
nipkow@48849
   961
by(fact setprod.F_cong)
nipkow@15402
   962
nipkow@48849
   963
lemma strong_setprod_cong:
berghofe@16632
   964
  "A = B ==> (!!x. x:B =simp=> f x = g x) ==> setprod f A = setprod g B"
nipkow@48849
   965
by(fact setprod.strong_F_cong)
berghofe@16632
   966
nipkow@15402
   967
lemma setprod_reindex_cong: "inj_on f A ==>
nipkow@15402
   968
    B = f ` A ==> g = h \<circ> f ==> setprod h B = setprod g A"
nipkow@28853
   969
by (frule setprod_reindex, simp)
nipkow@15402
   970
chaieb@29674
   971
lemma strong_setprod_reindex_cong: assumes i: "inj_on f A"
chaieb@29674
   972
  and B: "B = f ` A" and eq: "\<And>x. x \<in> A \<Longrightarrow> g x = (h \<circ> f) x"
chaieb@29674
   973
  shows "setprod h B = setprod g A"
chaieb@29674
   974
proof-
chaieb@29674
   975
    have "setprod h B = setprod (h o f) A"
chaieb@29674
   976
      by (simp add: B setprod_reindex[OF i, of h])
chaieb@29674
   977
    then show ?thesis apply simp
chaieb@29674
   978
      apply (rule setprod_cong)
chaieb@29674
   979
      apply simp
nipkow@30837
   980
      by (simp add: eq)
chaieb@29674
   981
qed
chaieb@29674
   982
nipkow@48893
   983
lemma setprod_Un_one: "\<lbrakk> finite S; finite T; \<forall>x \<in> S\<inter>T. f x = 1 \<rbrakk>
nipkow@48893
   984
  \<Longrightarrow> setprod f (S \<union> T) = setprod f S  * setprod f T"
nipkow@48893
   985
by(fact setprod.F_Un_neutral)
nipkow@15402
   986
nipkow@48821
   987
lemmas setprod_1 = setprod.F_neutral
nipkow@48821
   988
lemmas setprod_1' = setprod.F_neutral'
nipkow@15402
   989
nipkow@15402
   990
nipkow@15402
   991
lemma setprod_Un_Int: "finite A ==> finite B
nipkow@15402
   992
    ==> setprod g (A Un B) * setprod g (A Int B) = setprod g A * setprod g B"
nipkow@48849
   993
by (fact setprod.union_inter)
nipkow@15402
   994
nipkow@15402
   995
lemma setprod_Un_disjoint: "finite A ==> finite B
nipkow@15402
   996
  ==> A Int B = {} ==> setprod g (A Un B) = setprod g A * setprod g B"
nipkow@48849
   997
by (fact setprod.union_disjoint)
nipkow@48849
   998
nipkow@48849
   999
lemma setprod_subset_diff: "\<lbrakk> B \<subseteq> A; finite A \<rbrakk> \<Longrightarrow>
nipkow@48849
  1000
    setprod f A = setprod f (A - B) * setprod f B"
nipkow@48849
  1001
by(fact setprod.F_subset_diff)
nipkow@15402
  1002
nipkow@48849
  1003
lemma setprod_mono_one_left:
nipkow@48849
  1004
  "\<lbrakk> finite T; S \<subseteq> T; \<forall>i \<in> T - S. f i = 1 \<rbrakk> \<Longrightarrow> setprod f S = setprod f T"
nipkow@48849
  1005
by(fact setprod.F_mono_neutral_left)
nipkow@30837
  1006
nipkow@48849
  1007
lemmas setprod_mono_one_right = setprod.F_mono_neutral_right
nipkow@30837
  1008
nipkow@48849
  1009
lemma setprod_mono_one_cong_left: 
nipkow@48849
  1010
  "\<lbrakk> finite T; S \<subseteq> T; \<forall>i \<in> T - S. g i = 1; \<And>x. x \<in> S \<Longrightarrow> f x = g x \<rbrakk>
nipkow@48849
  1011
  \<Longrightarrow> setprod f S = setprod g T"
nipkow@48849
  1012
by(fact setprod.F_mono_neutral_cong_left)
nipkow@48849
  1013
nipkow@48849
  1014
lemmas setprod_mono_one_cong_right = setprod.F_mono_neutral_cong_right
chaieb@29674
  1015
nipkow@48849
  1016
lemma setprod_delta: "finite S \<Longrightarrow>
nipkow@48849
  1017
  setprod (\<lambda>k. if k=a then b k else 1) S = (if a \<in> S then b a else 1)"
nipkow@48849
  1018
by(fact setprod.F_delta)
chaieb@29674
  1019
nipkow@48849
  1020
lemma setprod_delta': "finite S \<Longrightarrow>
nipkow@48849
  1021
  setprod (\<lambda>k. if a = k then b k else 1) S = (if a\<in> S then b a else 1)"
nipkow@48849
  1022
by(fact setprod.F_delta')
chaieb@29674
  1023
nipkow@15402
  1024
lemma setprod_UN_disjoint:
nipkow@15402
  1025
    "finite I ==> (ALL i:I. finite (A i)) ==>
nipkow@15402
  1026
        (ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {}) ==>
nipkow@15402
  1027
      setprod f (UNION I A) = setprod (%i. setprod f (A i)) I"
wenzelm@41550
  1028
  by (simp add: setprod_def fold_image_UN_disjoint)
nipkow@15402
  1029
nipkow@15402
  1030
lemma setprod_Union_disjoint:
hoelzl@44937
  1031
  assumes "\<forall>A\<in>C. finite A" "\<forall>A\<in>C. \<forall>B\<in>C. A \<noteq> B \<longrightarrow> A Int B = {}" 
hoelzl@44937
  1032
  shows "setprod f (Union C) = setprod (setprod f) C"
hoelzl@44937
  1033
proof cases
hoelzl@44937
  1034
  assume "finite C"
hoelzl@44937
  1035
  from setprod_UN_disjoint[OF this assms]
hoelzl@44937
  1036
  show ?thesis
hoelzl@44937
  1037
    by (simp add: SUP_def)
hoelzl@44937
  1038
qed (force dest: finite_UnionD simp add: setprod_def)
nipkow@15402
  1039
nipkow@15402
  1040
lemma setprod_Sigma: "finite A ==> ALL x:A. finite (B x) ==>
nipkow@16550
  1041
    (\<Prod>x\<in>A. (\<Prod>y\<in> B x. f x y)) =
paulson@17189
  1042
    (\<Prod>(x,y)\<in>(SIGMA x:A. B x). f x y)"
wenzelm@41550
  1043
by(simp add:setprod_def fold_image_Sigma split_def)
nipkow@15402
  1044
paulson@15409
  1045
text{*Here we can eliminate the finiteness assumptions, by cases.*}
paulson@15409
  1046
lemma setprod_cartesian_product: 
paulson@17189
  1047
     "(\<Prod>x\<in>A. (\<Prod>y\<in> B. f x y)) = (\<Prod>(x,y)\<in>(A <*> B). f x y)"
paulson@15409
  1048
apply (cases "finite A") 
paulson@15409
  1049
 apply (cases "finite B") 
paulson@15409
  1050
  apply (simp add: setprod_Sigma)
paulson@15409
  1051
 apply (cases "A={}", simp)
nipkow@48849
  1052
 apply (simp) 
paulson@15409
  1053
apply (auto simp add: setprod_def
paulson@15409
  1054
            dest: finite_cartesian_productD1 finite_cartesian_productD2) 
paulson@15409
  1055
done
nipkow@15402
  1056
nipkow@48861
  1057
lemma setprod_timesf: "setprod (%x. f x * g x) A = (setprod f A * setprod g A)"
nipkow@48861
  1058
by (fact setprod.F_fun_f)
nipkow@15402
  1059
nipkow@15402
  1060
nipkow@15402
  1061
subsubsection {* Properties in more restricted classes of structures *}
nipkow@15402
  1062
nipkow@15402
  1063
lemma setprod_eq_1_iff [simp]:
nipkow@28853
  1064
  "finite F ==> (setprod f F = 1) = (ALL a:F. f a = (1::nat))"
nipkow@28853
  1065
by (induct set: finite) auto
nipkow@15402
  1066
nipkow@15402
  1067
lemma setprod_zero:
huffman@23277
  1068
     "finite A ==> EX x: A. f x = (0::'a::comm_semiring_1) ==> setprod f A = 0"
nipkow@28853
  1069
apply (induct set: finite, force, clarsimp)
nipkow@28853
  1070
apply (erule disjE, auto)
nipkow@28853
  1071
done
nipkow@15402
  1072
nipkow@15402
  1073
lemma setprod_nonneg [rule_format]:
haftmann@35028
  1074
   "(ALL x: A. (0::'a::linordered_semidom) \<le> f x) --> 0 \<le> setprod f A"
huffman@30841
  1075
by (cases "finite A", induct set: finite, simp_all add: mult_nonneg_nonneg)
huffman@30841
  1076
haftmann@35028
  1077
lemma setprod_pos [rule_format]: "(ALL x: A. (0::'a::linordered_semidom) < f x)
nipkow@28853
  1078
  --> 0 < setprod f A"
huffman@30841
  1079
by (cases "finite A", induct set: finite, simp_all add: mult_pos_pos)
nipkow@15402
  1080
nipkow@30843
  1081
lemma setprod_zero_iff[simp]: "finite A ==> 
nipkow@30843
  1082
  (setprod f A = (0::'a::{comm_semiring_1,no_zero_divisors})) =
nipkow@30843
  1083
  (EX x: A. f x = 0)"
nipkow@30843
  1084
by (erule finite_induct, auto simp:no_zero_divisors)
nipkow@30843
  1085
nipkow@30843
  1086
lemma setprod_pos_nat:
nipkow@30843
  1087
  "finite S ==> (ALL x : S. f x > (0::nat)) ==> setprod f S > 0"
nipkow@30843
  1088
using setprod_zero_iff by(simp del:neq0_conv add:neq0_conv[symmetric])
nipkow@15402
  1089
nipkow@30863
  1090
lemma setprod_pos_nat_iff[simp]:
nipkow@30863
  1091
  "finite S ==> (setprod f S > 0) = (ALL x : S. f x > (0::nat))"
nipkow@30863
  1092
using setprod_zero_iff by(simp del:neq0_conv add:neq0_conv[symmetric])
nipkow@30863
  1093
nipkow@15402
  1094
lemma setprod_Un: "finite A ==> finite B ==> (ALL x: A Int B. f x \<noteq> 0) ==>
nipkow@28853
  1095
  (setprod f (A Un B) :: 'a ::{field})
nipkow@28853
  1096
   = setprod f A * setprod f B / setprod f (A Int B)"
nipkow@30843
  1097
by (subst setprod_Un_Int [symmetric], auto)
nipkow@15402
  1098
haftmann@49715
  1099
lemma setprod_Un2:
haftmann@49715
  1100
  assumes "finite (A \<union> B)"
haftmann@49715
  1101
  shows "setprod f (A \<union> B) = setprod f (A - B) * setprod f (B - A) * setprod f (A \<inter> B)"
haftmann@49715
  1102
proof -
haftmann@49715
  1103
  have "A \<union> B = A - B \<union> (B - A) \<union> A \<inter> B"
haftmann@49715
  1104
    by auto
haftmann@49715
  1105
  with assms show ?thesis by simp (subst setprod_Un_disjoint, auto)+
haftmann@49715
  1106
qed
haftmann@49715
  1107
nipkow@15402
  1108
lemma setprod_diff1: "finite A ==> f a \<noteq> 0 ==>
nipkow@28853
  1109
  (setprod f (A - {a}) :: 'a :: {field}) =
nipkow@28853
  1110
  (if a:A then setprod f A / f a else setprod f A)"
haftmann@36303
  1111
  by (erule finite_induct) (auto simp add: insert_Diff_if)
nipkow@15402
  1112
paulson@31906
  1113
lemma setprod_inversef: 
haftmann@36409
  1114
  fixes f :: "'b \<Rightarrow> 'a::field_inverse_zero"
paulson@31906
  1115
  shows "finite A ==> setprod (inverse \<circ> f) A = inverse (setprod f A)"
nipkow@28853
  1116
by (erule finite_induct) auto
nipkow@15402
  1117
nipkow@15402
  1118
lemma setprod_dividef:
haftmann@36409
  1119
  fixes f :: "'b \<Rightarrow> 'a::field_inverse_zero"
wenzelm@31916
  1120
  shows "finite A
nipkow@28853
  1121
    ==> setprod (%x. f x / g x) A = setprod f A / setprod g A"
nipkow@28853
  1122
apply (subgoal_tac
nipkow@15402
  1123
         "setprod (%x. f x / g x) A = setprod (%x. f x * (inverse \<circ> g) x) A")
nipkow@28853
  1124
apply (erule ssubst)
nipkow@28853
  1125
apply (subst divide_inverse)
nipkow@28853
  1126
apply (subst setprod_timesf)
nipkow@28853
  1127
apply (subst setprod_inversef, assumption+, rule refl)
nipkow@28853
  1128
apply (rule setprod_cong, rule refl)
nipkow@28853
  1129
apply (subst divide_inverse, auto)
nipkow@28853
  1130
done
nipkow@28853
  1131
nipkow@29925
  1132
lemma setprod_dvd_setprod [rule_format]: 
nipkow@29925
  1133
    "(ALL x : A. f x dvd g x) \<longrightarrow> setprod f A dvd setprod g A"
nipkow@29925
  1134
  apply (cases "finite A")
nipkow@29925
  1135
  apply (induct set: finite)
nipkow@29925
  1136
  apply (auto simp add: dvd_def)
nipkow@29925
  1137
  apply (rule_tac x = "k * ka" in exI)
nipkow@29925
  1138
  apply (simp add: algebra_simps)
nipkow@29925
  1139
done
nipkow@29925
  1140
nipkow@29925
  1141
lemma setprod_dvd_setprod_subset:
nipkow@29925
  1142
  "finite B \<Longrightarrow> A <= B \<Longrightarrow> setprod f A dvd setprod f B"
nipkow@29925
  1143
  apply (subgoal_tac "setprod f B = setprod f A * setprod f (B - A)")
nipkow@29925
  1144
  apply (unfold dvd_def, blast)
nipkow@29925
  1145
  apply (subst setprod_Un_disjoint [symmetric])
nipkow@29925
  1146
  apply (auto elim: finite_subset intro: setprod_cong)
nipkow@29925
  1147
done
nipkow@29925
  1148
nipkow@29925
  1149
lemma setprod_dvd_setprod_subset2:
nipkow@29925
  1150
  "finite B \<Longrightarrow> A <= B \<Longrightarrow> ALL x : A. (f x::'a::comm_semiring_1) dvd g x \<Longrightarrow> 
nipkow@29925
  1151
      setprod f A dvd setprod g B"
nipkow@29925
  1152
  apply (rule dvd_trans)
nipkow@29925
  1153
  apply (rule setprod_dvd_setprod, erule (1) bspec)
nipkow@29925
  1154
  apply (erule (1) setprod_dvd_setprod_subset)
nipkow@29925
  1155
done
nipkow@29925
  1156
nipkow@29925
  1157
lemma dvd_setprod: "finite A \<Longrightarrow> i:A \<Longrightarrow> 
nipkow@29925
  1158
    (f i ::'a::comm_semiring_1) dvd setprod f A"
nipkow@29925
  1159
by (induct set: finite) (auto intro: dvd_mult)
nipkow@29925
  1160
nipkow@29925
  1161
lemma dvd_setsum [rule_format]: "(ALL i : A. d dvd f i) \<longrightarrow> 
nipkow@29925
  1162
    (d::'a::comm_semiring_1) dvd (SUM x : A. f x)"
nipkow@29925
  1163
  apply (cases "finite A")
nipkow@29925
  1164
  apply (induct set: finite)
nipkow@29925
  1165
  apply auto
nipkow@29925
  1166
done
nipkow@29925
  1167
hoelzl@35171
  1168
lemma setprod_mono:
hoelzl@35171
  1169
  fixes f :: "'a \<Rightarrow> 'b\<Colon>linordered_semidom"
hoelzl@35171
  1170
  assumes "\<forall>i\<in>A. 0 \<le> f i \<and> f i \<le> g i"
hoelzl@35171
  1171
  shows "setprod f A \<le> setprod g A"
hoelzl@35171
  1172
proof (cases "finite A")
hoelzl@35171
  1173
  case True
hoelzl@35171
  1174
  hence ?thesis "setprod f A \<ge> 0" using subset_refl[of A]
hoelzl@35171
  1175
  proof (induct A rule: finite_subset_induct)
hoelzl@35171
  1176
    case (insert a F)
hoelzl@35171
  1177
    thus "setprod f (insert a F) \<le> setprod g (insert a F)" "0 \<le> setprod f (insert a F)"
hoelzl@35171
  1178
      unfolding setprod_insert[OF insert(1,3)]
hoelzl@35171
  1179
      using assms[rule_format,OF insert(2)] insert
hoelzl@35171
  1180
      by (auto intro: mult_mono mult_nonneg_nonneg)
hoelzl@35171
  1181
  qed auto
hoelzl@35171
  1182
  thus ?thesis by simp
hoelzl@35171
  1183
qed auto
hoelzl@35171
  1184
hoelzl@35171
  1185
lemma abs_setprod:
hoelzl@35171
  1186
  fixes f :: "'a \<Rightarrow> 'b\<Colon>{linordered_field,abs}"
hoelzl@35171
  1187
  shows "abs (setprod f A) = setprod (\<lambda>x. abs (f x)) A"
hoelzl@35171
  1188
proof (cases "finite A")
hoelzl@35171
  1189
  case True thus ?thesis
huffman@35216
  1190
    by induct (auto simp add: field_simps abs_mult)
hoelzl@35171
  1191
qed auto
hoelzl@35171
  1192
haftmann@31017
  1193
lemma setprod_constant: "finite A ==> (\<Prod>x\<in> A. (y::'a::{comm_monoid_mult})) = y^(card A)"
nipkow@28853
  1194
apply (erule finite_induct)
huffman@35216
  1195
apply auto
nipkow@28853
  1196
done
nipkow@15402
  1197
chaieb@29674
  1198
lemma setprod_gen_delta:
chaieb@29674
  1199
  assumes fS: "finite S"
haftmann@31017
  1200
  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)"
chaieb@29674
  1201
proof-
chaieb@29674
  1202
  let ?f = "(\<lambda>k. if k=a then b k else c)"
chaieb@29674
  1203
  {assume a: "a \<notin> S"
chaieb@29674
  1204
    hence "\<forall> k\<in> S. ?f k = c" by simp
nipkow@48849
  1205
    hence ?thesis  using a setprod_constant[OF fS, of c] by simp }
chaieb@29674
  1206
  moreover 
chaieb@29674
  1207
  {assume a: "a \<in> S"
chaieb@29674
  1208
    let ?A = "S - {a}"
chaieb@29674
  1209
    let ?B = "{a}"
chaieb@29674
  1210
    have eq: "S = ?A \<union> ?B" using a by blast 
chaieb@29674
  1211
    have dj: "?A \<inter> ?B = {}" by simp
chaieb@29674
  1212
    from fS have fAB: "finite ?A" "finite ?B" by auto  
chaieb@29674
  1213
    have fA0:"setprod ?f ?A = setprod (\<lambda>i. c) ?A"
chaieb@29674
  1214
      apply (rule setprod_cong) by auto
chaieb@29674
  1215
    have cA: "card ?A = card S - 1" using fS a by auto
chaieb@29674
  1216
    have fA1: "setprod ?f ?A = c ^ card ?A"  unfolding fA0 apply (rule setprod_constant) using fS by auto
chaieb@29674
  1217
    have "setprod ?f ?A * setprod ?f ?B = setprod ?f S"
chaieb@29674
  1218
      using setprod_Un_disjoint[OF fAB dj, of ?f, unfolded eq[symmetric]]
chaieb@29674
  1219
      by simp
chaieb@29674
  1220
    then have ?thesis using a cA
haftmann@36349
  1221
      by (simp add: fA1 field_simps cong add: setprod_cong cong del: if_weak_cong)}
chaieb@29674
  1222
  ultimately show ?thesis by blast
chaieb@29674
  1223
qed
chaieb@29674
  1224
chaieb@29674
  1225
haftmann@35816
  1226
subsection {* Versions of @{const inf} and @{const sup} on non-empty sets *}
haftmann@35816
  1227
haftmann@35816
  1228
no_notation times (infixl "*" 70)
haftmann@35816
  1229
no_notation Groups.one ("1")
haftmann@35816
  1230
haftmann@35816
  1231
locale semilattice_big = semilattice +
haftmann@35816
  1232
  fixes F :: "'a set \<Rightarrow> 'a"
haftmann@35816
  1233
  assumes F_eq: "finite A \<Longrightarrow> F A = fold1 (op *) A"
haftmann@35816
  1234
haftmann@35816
  1235
sublocale semilattice_big < folding_one_idem proof
haftmann@35816
  1236
qed (simp_all add: F_eq)
haftmann@35816
  1237
haftmann@35816
  1238
notation times (infixl "*" 70)
haftmann@35816
  1239
notation Groups.one ("1")
haftmann@22917
  1240
haftmann@35816
  1241
context lattice
haftmann@35816
  1242
begin
haftmann@35816
  1243
haftmann@35816
  1244
definition Inf_fin :: "'a set \<Rightarrow> 'a" ("\<Sqinter>\<^bsub>fin\<^esub>_" [900] 900) where
haftmann@35816
  1245
  "Inf_fin = fold1 inf"
haftmann@35816
  1246
haftmann@35816
  1247
definition Sup_fin :: "'a set \<Rightarrow> 'a" ("\<Squnion>\<^bsub>fin\<^esub>_" [900] 900) where
haftmann@35816
  1248
  "Sup_fin = fold1 sup"
haftmann@35816
  1249
haftmann@35816
  1250
end
haftmann@35816
  1251
haftmann@35816
  1252
sublocale lattice < Inf_fin!: semilattice_big inf Inf_fin proof
haftmann@35816
  1253
qed (simp add: Inf_fin_def)
haftmann@35816
  1254
haftmann@35816
  1255
sublocale lattice < Sup_fin!: semilattice_big sup Sup_fin proof
haftmann@35816
  1256
qed (simp add: Sup_fin_def)
haftmann@22917
  1257
haftmann@35028
  1258
context semilattice_inf
haftmann@26041
  1259
begin
haftmann@26041
  1260
haftmann@36635
  1261
lemma ab_semigroup_idem_mult_inf:
haftmann@36635
  1262
  "class.ab_semigroup_idem_mult inf"
haftmann@35816
  1263
proof qed (rule inf_assoc inf_commute inf_idem)+
haftmann@35816
  1264
haftmann@46033
  1265
lemma fold_inf_insert[simp]: "finite A \<Longrightarrow> Finite_Set.fold inf b (insert a A) = inf a (Finite_Set.fold inf b A)"
haftmann@42871
  1266
by(rule comp_fun_idem.fold_insert_idem[OF ab_semigroup_idem_mult.comp_fun_idem[OF ab_semigroup_idem_mult_inf]])
haftmann@35816
  1267
haftmann@46033
  1268
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"
haftmann@35816
  1269
by (induct pred: finite) (auto intro: le_infI1)
haftmann@35816
  1270
haftmann@46033
  1271
lemma fold_inf_le_inf: "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> Finite_Set.fold inf b A \<le> inf a b"
haftmann@35816
  1272
proof(induct arbitrary: a pred:finite)
haftmann@35816
  1273
  case empty thus ?case by simp
haftmann@35816
  1274
next
haftmann@35816
  1275
  case (insert x A)
haftmann@35816
  1276
  show ?case
haftmann@35816
  1277
  proof cases
haftmann@35816
  1278
    assume "A = {}" thus ?thesis using insert by simp
haftmann@35816
  1279
  next
haftmann@35816
  1280
    assume "A \<noteq> {}" thus ?thesis using insert by (auto intro: le_infI2)
haftmann@35816
  1281
  qed
haftmann@35816
  1282
qed
haftmann@35816
  1283
haftmann@26041
  1284
lemma below_fold1_iff:
haftmann@26041
  1285
  assumes "finite A" "A \<noteq> {}"
haftmann@26041
  1286
  shows "x \<le> fold1 inf A \<longleftrightarrow> (\<forall>a\<in>A. x \<le> a)"
haftmann@26041
  1287
proof -
haftmann@29509
  1288
  interpret ab_semigroup_idem_mult inf
haftmann@26041
  1289
    by (rule ab_semigroup_idem_mult_inf)
haftmann@26041
  1290
  show ?thesis using assms by (induct rule: finite_ne_induct) simp_all
haftmann@26041
  1291
qed
haftmann@26041
  1292
haftmann@26041
  1293
lemma fold1_belowI:
haftmann@26757
  1294
  assumes "finite A"
haftmann@26041
  1295
    and "a \<in> A"
haftmann@26041
  1296
  shows "fold1 inf A \<le> a"
haftmann@26757
  1297
proof -
haftmann@26757
  1298
  from assms have "A \<noteq> {}" by auto
haftmann@26757
  1299
  from `finite A` `A \<noteq> {}` `a \<in> A` show ?thesis
haftmann@26757
  1300
  proof (induct rule: finite_ne_induct)
haftmann@26757
  1301
    case singleton thus ?case by simp
haftmann@26041
  1302
  next
haftmann@29509
  1303
    interpret ab_semigroup_idem_mult inf
haftmann@26757
  1304
      by (rule ab_semigroup_idem_mult_inf)
haftmann@26757
  1305
    case (insert x F)
haftmann@26757
  1306
    from insert(5) have "a = x \<or> a \<in> F" by simp
haftmann@26757
  1307
    thus ?case
haftmann@26757
  1308
    proof
haftmann@26757
  1309
      assume "a = x" thus ?thesis using insert
nipkow@29667
  1310
        by (simp add: mult_ac)
haftmann@26757
  1311
    next
haftmann@26757
  1312
      assume "a \<in> F"
haftmann@26757
  1313
      hence bel: "fold1 inf F \<le> a" by (rule insert)
haftmann@26757
  1314
      have "inf (fold1 inf (insert x F)) a = inf x (inf (fold1 inf F) a)"
nipkow@29667
  1315
        using insert by (simp add: mult_ac)
haftmann@26757
  1316
      also have "inf (fold1 inf F) a = fold1 inf F"
haftmann@26757
  1317
        using bel by (auto intro: antisym)
haftmann@26757
  1318
      also have "inf x \<dots> = fold1 inf (insert x F)"
nipkow@29667
  1319
        using insert by (simp add: mult_ac)
haftmann@26757
  1320
      finally have aux: "inf (fold1 inf (insert x F)) a = fold1 inf (insert x F)" .
haftmann@26757
  1321
      moreover have "inf (fold1 inf (insert x F)) a \<le> a" by simp
haftmann@26757
  1322
      ultimately show ?thesis by simp
haftmann@26757
  1323
    qed
haftmann@26041
  1324
  qed
haftmann@26041
  1325
qed
haftmann@26041
  1326
haftmann@26041
  1327
end
haftmann@26041
  1328
haftmann@35816
  1329
context semilattice_sup
haftmann@22917
  1330
begin
haftmann@22917
  1331
haftmann@36635
  1332
lemma ab_semigroup_idem_mult_sup: "class.ab_semigroup_idem_mult sup"
haftmann@35816
  1333
by (rule semilattice_inf.ab_semigroup_idem_mult_inf)(rule dual_semilattice)
haftmann@35816
  1334
haftmann@46033
  1335
lemma fold_sup_insert[simp]: "finite A \<Longrightarrow> Finite_Set.fold sup b (insert a A) = sup a (Finite_Set.fold sup b A)"
haftmann@35816
  1336
by(rule semilattice_inf.fold_inf_insert)(rule dual_semilattice)
haftmann@22917
  1337
haftmann@46033
  1338
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"
haftmann@35816
  1339
by(rule semilattice_inf.inf_le_fold_inf)(rule dual_semilattice)
haftmann@35816
  1340
haftmann@46033
  1341
lemma sup_le_fold_sup: "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> sup a b \<le> Finite_Set.fold sup b A"
haftmann@35816
  1342
by(rule semilattice_inf.fold_inf_le_inf)(rule dual_semilattice)
haftmann@35816
  1343
haftmann@35816
  1344
end
haftmann@35816
  1345
haftmann@35816
  1346
context lattice
haftmann@35816
  1347
begin
haftmann@25062
  1348
wenzelm@31916
  1349
lemma Inf_le_Sup [simp]: "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> \<Sqinter>\<^bsub>fin\<^esub>A \<le> \<Squnion>\<^bsub>fin\<^esub>A"
haftmann@24342
  1350
apply(unfold Sup_fin_def Inf_fin_def)
nipkow@15500
  1351
apply(subgoal_tac "EX a. a:A")
nipkow@15500
  1352
prefer 2 apply blast
nipkow@15500
  1353
apply(erule exE)
haftmann@22388
  1354
apply(rule order_trans)
haftmann@26757
  1355
apply(erule (1) fold1_belowI)
haftmann@35028
  1356
apply(erule (1) semilattice_inf.fold1_belowI [OF dual_semilattice])
nipkow@15500
  1357
done
nipkow@15500
  1358
haftmann@24342
  1359
lemma sup_Inf_absorb [simp]:
wenzelm@31916
  1360
  "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> sup a (\<Sqinter>\<^bsub>fin\<^esub>A) = a"
nipkow@15512
  1361
apply(subst sup_commute)
haftmann@26041
  1362
apply(simp add: Inf_fin_def sup_absorb2 fold1_belowI)
nipkow@15504
  1363
done
nipkow@15504
  1364
haftmann@24342
  1365
lemma inf_Sup_absorb [simp]:
wenzelm@31916
  1366
  "finite A \<Longrightarrow> a \<in> A \<Longrightarrow> inf a (\<Squnion>\<^bsub>fin\<^esub>A) = a"
haftmann@26041
  1367
by (simp add: Sup_fin_def inf_absorb1
haftmann@35028
  1368
  semilattice_inf.fold1_belowI [OF dual_semilattice])
haftmann@24342
  1369
haftmann@24342
  1370
end
haftmann@24342
  1371
haftmann@24342
  1372
context distrib_lattice
haftmann@24342
  1373
begin
haftmann@24342
  1374
haftmann@24342
  1375
lemma sup_Inf1_distrib:
haftmann@26041
  1376
  assumes "finite A"
haftmann@26041
  1377
    and "A \<noteq> {}"
wenzelm@31916
  1378
  shows "sup x (\<Sqinter>\<^bsub>fin\<^esub>A) = \<Sqinter>\<^bsub>fin\<^esub>{sup x a|a. a \<in> A}"
haftmann@26041
  1379
proof -
haftmann@29509
  1380
  interpret ab_semigroup_idem_mult inf
haftmann@26041
  1381
    by (rule ab_semigroup_idem_mult_inf)
haftmann@26041
  1382
  from assms show ?thesis
haftmann@26041
  1383
    by (simp add: Inf_fin_def image_def
haftmann@26041
  1384
      hom_fold1_commute [where h="sup x", OF sup_inf_distrib1])
berghofe@26792
  1385
        (rule arg_cong [where f="fold1 inf"], blast)
haftmann@26041
  1386
qed
nipkow@18423
  1387
haftmann@24342
  1388
lemma sup_Inf2_distrib:
haftmann@24342
  1389
  assumes A: "finite A" "A \<noteq> {}" and B: "finite B" "B \<noteq> {}"
wenzelm@31916
  1390
  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}"
haftmann@24342
  1391
using A proof (induct rule: finite_ne_induct)
nipkow@15500
  1392
  case singleton thus ?case
wenzelm@41550
  1393
    by (simp add: sup_Inf1_distrib [OF B])
nipkow@15500
  1394
next
haftmann@29509
  1395
  interpret ab_semigroup_idem_mult inf
haftmann@26041
  1396
    by (rule ab_semigroup_idem_mult_inf)
nipkow@15500
  1397
  case (insert x A)
haftmann@25062
  1398
  have finB: "finite {sup x b |b. b \<in> B}"
haftmann@25062
  1399
    by(rule finite_surj[where f = "sup x", OF B(1)], auto)
haftmann@25062
  1400
  have finAB: "finite {sup a b |a b. a \<in> A \<and> b \<in> B}"
nipkow@15500
  1401
  proof -
haftmann@25062
  1402
    have "{sup a b |a b. a \<in> A \<and> b \<in> B} = (UN a:A. UN b:B. {sup a b})"
nipkow@15500
  1403
      by blast
berghofe@15517
  1404
    thus ?thesis by(simp add: insert(1) B(1))
nipkow@15500
  1405
  qed
haftmann@25062
  1406
  have ne: "{sup a b |a b. a \<in> A \<and> b \<in> B} \<noteq> {}" using insert B by blast
wenzelm@31916
  1407
  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)"
wenzelm@41550
  1408
    using insert by simp
wenzelm@31916
  1409
  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)
wenzelm@31916
  1410
  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})"
nipkow@15500
  1411
    using insert by(simp add:sup_Inf1_distrib[OF B])
wenzelm@31916
  1412
  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})"
wenzelm@31916
  1413
    (is "_ = \<Sqinter>\<^bsub>fin\<^esub>?M")
nipkow@15500
  1414
    using B insert
haftmann@26041
  1415
    by (simp add: Inf_fin_def fold1_Un2 [OF finB _ finAB ne])
haftmann@25062
  1416
  also have "?M = {sup a b |a b. a \<in> insert x A \<and> b \<in> B}"
nipkow@15500
  1417
    by blast
nipkow@15500
  1418
  finally show ?case .
nipkow@15500
  1419
qed
nipkow@15500
  1420
haftmann@24342
  1421
lemma inf_Sup1_distrib:
haftmann@26041
  1422
  assumes "finite A" and "A \<noteq> {}"
wenzelm@31916
  1423
  shows "inf x (\<Squnion>\<^bsub>fin\<^esub>A) = \<Squnion>\<^bsub>fin\<^esub>{inf x a|a. a \<in> A}"
haftmann@26041
  1424
proof -
haftmann@29509
  1425
  interpret ab_semigroup_idem_mult sup
haftmann@26041
  1426
    by (rule ab_semigroup_idem_mult_sup)
haftmann@26041
  1427
  from assms show ?thesis
haftmann@26041
  1428
    by (simp add: Sup_fin_def image_def hom_fold1_commute [where h="inf x", OF inf_sup_distrib1])
berghofe@26792
  1429
      (rule arg_cong [where f="fold1 sup"], blast)
haftmann@26041
  1430
qed
nipkow@18423
  1431
haftmann@24342
  1432
lemma inf_Sup2_distrib:
haftmann@24342
  1433
  assumes A: "finite A" "A \<noteq> {}" and B: "finite B" "B \<noteq> {}"
wenzelm@31916
  1434
  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}"
haftmann@24342
  1435
using A proof (induct rule: finite_ne_induct)
nipkow@18423
  1436
  case singleton thus ?case
huffman@44921
  1437
    by(simp add: inf_Sup1_distrib [OF B])
nipkow@18423
  1438
next
nipkow@18423
  1439
  case (insert x A)
haftmann@25062
  1440
  have finB: "finite {inf x b |b. b \<in> B}"
haftmann@25062
  1441
    by(rule finite_surj[where f = "%b. inf x b", OF B(1)], auto)
haftmann@25062
  1442
  have finAB: "finite {inf a b |a b. a \<in> A \<and> b \<in> B}"
nipkow@18423
  1443
  proof -
haftmann@25062
  1444
    have "{inf a b |a b. a \<in> A \<and> b \<in> B} = (UN a:A. UN b:B. {inf a b})"
nipkow@18423
  1445
      by blast
nipkow@18423
  1446
    thus ?thesis by(simp add: insert(1) B(1))
nipkow@18423
  1447
  qed
haftmann@25062
  1448
  have ne: "{inf a b |a b. a \<in> A \<and> b \<in> B} \<noteq> {}" using insert B by blast
haftmann@29509
  1449
  interpret ab_semigroup_idem_mult sup
haftmann@26041
  1450
    by (rule ab_semigroup_idem_mult_sup)
wenzelm@31916
  1451
  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)"
wenzelm@41550
  1452
    using insert by simp
wenzelm@31916
  1453
  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)
wenzelm@31916
  1454
  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})"
nipkow@18423
  1455
    using insert by(simp add:inf_Sup1_distrib[OF B])
wenzelm@31916
  1456
  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})"
wenzelm@31916
  1457
    (is "_ = \<Squnion>\<^bsub>fin\<^esub>?M")
nipkow@18423
  1458
    using B insert
haftmann@26041
  1459
    by (simp add: Sup_fin_def fold1_Un2 [OF finB _ finAB ne])
haftmann@25062
  1460
  also have "?M = {inf a b |a b. a \<in> insert x A \<and> b \<in> B}"
nipkow@18423
  1461
    by blast
nipkow@18423
  1462
  finally show ?case .
nipkow@18423
  1463
qed
nipkow@18423
  1464
haftmann@24342
  1465
end
haftmann@24342
  1466
haftmann@35719
  1467
context complete_lattice
haftmann@35719
  1468
begin
haftmann@35719
  1469
haftmann@35719
  1470
lemma Inf_fin_Inf:
haftmann@35719
  1471
  assumes "finite A" and "A \<noteq> {}"
haftmann@35719
  1472
  shows "\<Sqinter>\<^bsub>fin\<^esub>A = Inf A"
haftmann@35719
  1473
proof -
haftmann@35719
  1474
  interpret ab_semigroup_idem_mult inf
haftmann@35719
  1475
    by (rule ab_semigroup_idem_mult_inf)
noschinl@44918
  1476
  from `A \<noteq> {}` obtain b B where "A = {b} \<union> B" by auto
haftmann@35719
  1477
  moreover with `finite A` have "finite B" by simp
noschinl@44918
  1478
  ultimately show ?thesis
noschinl@44918
  1479
    by (simp add: Inf_fin_def fold1_eq_fold_idem inf_Inf_fold_inf [symmetric])
haftmann@35719
  1480
qed
haftmann@35719
  1481
haftmann@35719
  1482
lemma Sup_fin_Sup:
haftmann@35719
  1483
  assumes "finite A" and "A \<noteq> {}"
haftmann@35719
  1484
  shows "\<Squnion>\<^bsub>fin\<^esub>A = Sup A"
haftmann@35719
  1485
proof -
haftmann@35719
  1486
  interpret ab_semigroup_idem_mult sup
haftmann@35719
  1487
    by (rule ab_semigroup_idem_mult_sup)
noschinl@44918
  1488
  from `A \<noteq> {}` obtain b B where "A = {b} \<union> B" by auto
haftmann@35719
  1489
  moreover with `finite A` have "finite B" by simp
haftmann@35719
  1490
  ultimately show ?thesis  
haftmann@35719
  1491
  by (simp add: Sup_fin_def fold1_eq_fold_idem sup_Sup_fold_sup [symmetric])
haftmann@35719
  1492
qed
haftmann@35719
  1493
haftmann@35719
  1494
end
haftmann@35719
  1495
haftmann@22917
  1496
haftmann@35816
  1497
subsection {* Versions of @{const min} and @{const max} on non-empty sets *}
haftmann@35816
  1498
haftmann@35816
  1499
definition (in linorder) Min :: "'a set \<Rightarrow> 'a" where
haftmann@35816
  1500
  "Min = fold1 min"
haftmann@22917
  1501
haftmann@35816
  1502
definition (in linorder) Max :: "'a set \<Rightarrow> 'a" where
haftmann@35816
  1503
  "Max = fold1 max"
haftmann@35816
  1504
haftmann@35816
  1505
sublocale linorder < Min!: semilattice_big min Min proof
haftmann@35816
  1506
qed (simp add: Min_def)
haftmann@35816
  1507
haftmann@35816
  1508
sublocale linorder < Max!: semilattice_big max Max proof
haftmann@35816
  1509
qed (simp add: Max_def)
haftmann@22917
  1510
haftmann@24342
  1511
context linorder
haftmann@22917
  1512
begin
haftmann@22917
  1513
haftmann@35816
  1514
lemmas Min_singleton = Min.singleton
haftmann@35816
  1515
lemmas Max_singleton = Max.singleton
haftmann@35816
  1516
haftmann@35816
  1517
lemma Min_insert:
haftmann@35816
  1518
  assumes "finite A" and "A \<noteq> {}"
haftmann@35816
  1519
  shows "Min (insert x A) = min x (Min A)"
haftmann@35816
  1520
  using assms by simp
haftmann@35816
  1521
haftmann@35816
  1522
lemma Max_insert:
haftmann@35816
  1523
  assumes "finite A" and "A \<noteq> {}"
haftmann@35816
  1524
  shows "Max (insert x A) = max x (Max A)"
haftmann@35816
  1525
  using assms by simp
haftmann@35816
  1526
haftmann@35816
  1527
lemma Min_Un:
haftmann@35816
  1528
  assumes "finite A" and "A \<noteq> {}" and "finite B" and "B \<noteq> {}"
haftmann@35816
  1529
  shows "Min (A \<union> B) = min (Min A) (Min B)"
haftmann@35816
  1530
  using assms by (rule Min.union_idem)
haftmann@35816
  1531
haftmann@35816
  1532
lemma Max_Un:
haftmann@35816
  1533
  assumes "finite A" and "A \<noteq> {}" and "finite B" and "B \<noteq> {}"
haftmann@35816
  1534
  shows "Max (A \<union> B) = max (Max A) (Max B)"
haftmann@35816
  1535
  using assms by (rule Max.union_idem)
haftmann@35816
  1536
haftmann@35816
  1537
lemma hom_Min_commute:
haftmann@35816
  1538
  assumes "\<And>x y. h (min x y) = min (h x) (h y)"
haftmann@35816
  1539
    and "finite N" and "N \<noteq> {}"
haftmann@35816
  1540
  shows "h (Min N) = Min (h ` N)"
haftmann@35816
  1541
  using assms by (rule Min.hom_commute)
haftmann@35816
  1542
haftmann@35816
  1543
lemma hom_Max_commute:
haftmann@35816
  1544
  assumes "\<And>x y. h (max x y) = max (h x) (h y)"
haftmann@35816
  1545
    and "finite N" and "N \<noteq> {}"
haftmann@35816
  1546
  shows "h (Max N) = Max (h ` N)"
haftmann@35816
  1547
  using assms by (rule Max.hom_commute)
haftmann@35816
  1548
haftmann@26041
  1549
lemma ab_semigroup_idem_mult_min:
haftmann@36635
  1550
  "class.ab_semigroup_idem_mult min"
haftmann@28823
  1551
  proof qed (auto simp add: min_def)
haftmann@26041
  1552
haftmann@26041
  1553
lemma ab_semigroup_idem_mult_max:
haftmann@36635
  1554
  "class.ab_semigroup_idem_mult max"
haftmann@28823
  1555
  proof qed (auto simp add: max_def)
haftmann@26041
  1556
haftmann@26041
  1557
lemma max_lattice:
krauss@44845
  1558
  "class.semilattice_inf max (op \<ge>) (op >)"
haftmann@32203
  1559
  by (fact min_max.dual_semilattice)
haftmann@26041
  1560
haftmann@26041
  1561
lemma dual_max:
haftmann@26041
  1562
  "ord.max (op \<ge>) = min"
wenzelm@46904
  1563
  by (auto simp add: ord.max_def min_def fun_eq_iff)
haftmann@26041
  1564
haftmann@26041
  1565
lemma dual_min:
haftmann@26041
  1566
  "ord.min (op \<ge>) = max"
wenzelm@46904
  1567
  by (auto simp add: ord.min_def max_def fun_eq_iff)
haftmann@26041
  1568
haftmann@26041
  1569
lemma strict_below_fold1_iff:
haftmann@26041
  1570
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1571
  shows "x < fold1 min A \<longleftrightarrow> (\<forall>a\<in>A. x < a)"
haftmann@26041
  1572
proof -
haftmann@29509
  1573
  interpret ab_semigroup_idem_mult min
haftmann@26041
  1574
    by (rule ab_semigroup_idem_mult_min)
haftmann@26041
  1575
  from assms show ?thesis
haftmann@26041
  1576
  by (induct rule: finite_ne_induct)
haftmann@26041
  1577
    (simp_all add: fold1_insert)
haftmann@26041
  1578
qed
haftmann@26041
  1579
haftmann@26041
  1580
lemma fold1_below_iff:
haftmann@26041
  1581
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1582
  shows "fold1 min A \<le> x \<longleftrightarrow> (\<exists>a\<in>A. a \<le> x)"
haftmann@26041
  1583
proof -
haftmann@29509
  1584
  interpret ab_semigroup_idem_mult min
haftmann@26041
  1585
    by (rule ab_semigroup_idem_mult_min)
haftmann@26041
  1586
  from assms show ?thesis
haftmann@26041
  1587
  by (induct rule: finite_ne_induct)
haftmann@26041
  1588
    (simp_all add: fold1_insert min_le_iff_disj)
haftmann@26041
  1589
qed
haftmann@26041
  1590
haftmann@26041
  1591
lemma fold1_strict_below_iff:
haftmann@26041
  1592
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1593
  shows "fold1 min A < x \<longleftrightarrow> (\<exists>a\<in>A. a < x)"
haftmann@26041
  1594
proof -
haftmann@29509
  1595
  interpret ab_semigroup_idem_mult min
haftmann@26041
  1596
    by (rule ab_semigroup_idem_mult_min)
haftmann@26041
  1597
  from assms show ?thesis
haftmann@26041
  1598
  by (induct rule: finite_ne_induct)
haftmann@26041
  1599
    (simp_all add: fold1_insert min_less_iff_disj)
haftmann@26041
  1600
qed
haftmann@26041
  1601
haftmann@26041
  1602
lemma fold1_antimono:
haftmann@26041
  1603
  assumes "A \<noteq> {}" and "A \<subseteq> B" and "finite B"
haftmann@26041
  1604
  shows "fold1 min B \<le> fold1 min A"
haftmann@26041
  1605
proof cases
haftmann@26041
  1606
  assume "A = B" thus ?thesis by simp
haftmann@26041
  1607
next
haftmann@29509
  1608
  interpret ab_semigroup_idem_mult min
haftmann@26041
  1609
    by (rule ab_semigroup_idem_mult_min)
wenzelm@41550
  1610
  assume neq: "A \<noteq> B"
haftmann@26041
  1611
  have B: "B = A \<union> (B-A)" using `A \<subseteq> B` by blast
haftmann@26041
  1612
  have "fold1 min B = fold1 min (A \<union> (B-A))" by(subst B)(rule refl)
haftmann@26041
  1613
  also have "\<dots> = min (fold1 min A) (fold1 min (B-A))"
haftmann@26041
  1614
  proof -
haftmann@26041
  1615
    have "finite A" by(rule finite_subset[OF `A \<subseteq> B` `finite B`])
wenzelm@41550
  1616
    moreover have "finite(B-A)" by(rule finite_Diff[OF `finite B`])
wenzelm@41550
  1617
    moreover have "(B-A) \<noteq> {}" using assms neq by blast
wenzelm@41550
  1618
    moreover have "A Int (B-A) = {}" using assms by blast
haftmann@26041
  1619
    ultimately show ?thesis using `A \<noteq> {}` by (rule_tac fold1_Un)
haftmann@26041
  1620
  qed
haftmann@26041
  1621
  also have "\<dots> \<le> fold1 min A" by (simp add: min_le_iff_disj)
haftmann@26041
  1622
  finally show ?thesis .
haftmann@26041
  1623
qed
haftmann@26041
  1624
paulson@24427
  1625
lemma Min_in [simp]:
haftmann@26041
  1626
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1627
  shows "Min A \<in> A"
haftmann@26041
  1628
proof -
haftmann@29509
  1629
  interpret ab_semigroup_idem_mult min
haftmann@26041
  1630
    by (rule ab_semigroup_idem_mult_min)
nipkow@44890
  1631
  from assms fold1_in show ?thesis by (fastforce simp: Min_def min_def)
haftmann@26041
  1632
qed
nipkow@15392
  1633
paulson@24427
  1634
lemma Max_in [simp]:
haftmann@26041
  1635
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1636
  shows "Max A \<in> A"
haftmann@26041
  1637
proof -
haftmann@29509
  1638
  interpret ab_semigroup_idem_mult max
haftmann@26041
  1639
    by (rule ab_semigroup_idem_mult_max)
nipkow@44890
  1640
  from assms fold1_in [of A] show ?thesis by (fastforce simp: Max_def max_def)
haftmann@26041
  1641
qed
haftmann@26041
  1642
haftmann@26041
  1643
lemma Min_le [simp]:
haftmann@26757
  1644
  assumes "finite A" and "x \<in> A"
haftmann@26041
  1645
  shows "Min A \<le> x"
haftmann@32203
  1646
  using assms by (simp add: Min_def min_max.fold1_belowI)
haftmann@26041
  1647
haftmann@26041
  1648
lemma Max_ge [simp]:
haftmann@26757
  1649
  assumes "finite A" and "x \<in> A"
haftmann@26041
  1650
  shows "x \<le> Max A"
huffman@44921
  1651
  by (simp add: Max_def semilattice_inf.fold1_belowI [OF max_lattice] assms)
haftmann@26041
  1652
blanchet@35828
  1653
lemma Min_ge_iff [simp, no_atp]:
haftmann@26041
  1654
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1655
  shows "x \<le> Min A \<longleftrightarrow> (\<forall>a\<in>A. x \<le> a)"
haftmann@32203
  1656
  using assms by (simp add: Min_def min_max.below_fold1_iff)
haftmann@26041
  1657
blanchet@35828
  1658
lemma Max_le_iff [simp, no_atp]:
haftmann@26041
  1659
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1660
  shows "Max A \<le> x \<longleftrightarrow> (\<forall>a\<in>A. a \<le> x)"
huffman@44921
  1661
  by (simp add: Max_def semilattice_inf.below_fold1_iff [OF max_lattice] assms)
haftmann@26041
  1662
blanchet@35828
  1663
lemma Min_gr_iff [simp, no_atp]:
haftmann@26041
  1664
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1665
  shows "x < Min A \<longleftrightarrow> (\<forall>a\<in>A. x < a)"
haftmann@32203
  1666
  using assms by (simp add: Min_def strict_below_fold1_iff)
haftmann@26041
  1667
blanchet@35828
  1668
lemma Max_less_iff [simp, no_atp]:
haftmann@26041
  1669
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1670
  shows "Max A < x \<longleftrightarrow> (\<forall>a\<in>A. a < x)"
huffman@44921
  1671
  by (simp add: Max_def linorder.dual_max [OF dual_linorder]
huffman@44921
  1672
    linorder.strict_below_fold1_iff [OF dual_linorder] assms)
nipkow@18493
  1673
blanchet@35828
  1674
lemma Min_le_iff [no_atp]:
haftmann@26041
  1675
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1676
  shows "Min A \<le> x \<longleftrightarrow> (\<exists>a\<in>A. a \<le> x)"
haftmann@32203
  1677
  using assms by (simp add: Min_def fold1_below_iff)
nipkow@15497
  1678
blanchet@35828
  1679
lemma Max_ge_iff [no_atp]:
haftmann@26041
  1680
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1681
  shows "x \<le> Max A \<longleftrightarrow> (\<exists>a\<in>A. x \<le> a)"
huffman@44921
  1682
  by (simp add: Max_def linorder.dual_max [OF dual_linorder]
huffman@44921
  1683
    linorder.fold1_below_iff [OF dual_linorder] assms)
haftmann@22917
  1684
blanchet@35828
  1685
lemma Min_less_iff [no_atp]:
haftmann@26041
  1686
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1687
  shows "Min A < x \<longleftrightarrow> (\<exists>a\<in>A. a < x)"
haftmann@32203
  1688
  using assms by (simp add: Min_def fold1_strict_below_iff)
haftmann@22917
  1689
blanchet@35828
  1690
lemma Max_gr_iff [no_atp]:
haftmann@26041
  1691
  assumes "finite A" and "A \<noteq> {}"
haftmann@26041
  1692
  shows "x < Max A \<longleftrightarrow> (\<exists>a\<in>A. x < a)"
huffman@44921
  1693
  by (simp add: Max_def linorder.dual_max [OF dual_linorder]
huffman@44921
  1694
    linorder.fold1_strict_below_iff [OF dual_linorder] assms)
haftmann@26041
  1695
haftmann@30325
  1696
lemma Min_eqI:
haftmann@30325
  1697
  assumes "finite A"
haftmann@30325
  1698
  assumes "\<And>y. y \<in> A \<Longrightarrow> y \<ge> x"
haftmann@30325
  1699
    and "x \<in> A"
haftmann@30325
  1700
  shows "Min A = x"
haftmann@30325
  1701
proof (rule antisym)
haftmann@30325
  1702
  from `x \<in> A` have "A \<noteq> {}" by auto
haftmann@30325
  1703
  with assms show "Min A \<ge> x" by simp
haftmann@30325
  1704
next
haftmann@30325
  1705
  from assms show "x \<ge> Min A" by simp
haftmann@30325
  1706
qed
haftmann@30325
  1707
haftmann@30325
  1708
lemma Max_eqI:
haftmann@30325
  1709
  assumes "finite A"
haftmann@30325
  1710
  assumes "\<And>y. y \<in> A \<Longrightarrow> y \<le> x"
haftmann@30325
  1711
    and "x \<in> A"
haftmann@30325
  1712
  shows "Max A = x"
haftmann@30325
  1713
proof (rule antisym)
haftmann@30325
  1714
  from `x \<in> A` have "A \<noteq> {}" by auto
haftmann@30325
  1715
  with assms show "Max A \<le> x" by simp
haftmann@30325
  1716
next
haftmann@30325
  1717
  from assms show "x \<le> Max A" by simp
haftmann@30325
  1718
qed
haftmann@30325
  1719
haftmann@26041
  1720
lemma Min_antimono:
haftmann@26041
  1721
  assumes "M \<subseteq> N" and "M \<noteq> {}" and "finite N"
haftmann@26041
  1722
  shows "Min N \<le> Min M"
haftmann@32203
  1723
  using assms by (simp add: Min_def fold1_antimono)
haftmann@26041
  1724
haftmann@26041
  1725
lemma Max_mono:
haftmann@26041
  1726
  assumes "M \<subseteq> N" and "M \<noteq> {}" and "finite N"
haftmann@26041
  1727
  shows "Max M \<le> Max N"
huffman@44921
  1728
  by (simp add: Max_def linorder.dual_max [OF dual_linorder]
huffman@44921
  1729
    linorder.fold1_antimono [OF dual_linorder] assms)
haftmann@22917
  1730
nipkow@32006
  1731
lemma finite_linorder_max_induct[consumes 1, case_names empty insert]:
urbanc@36079
  1732
 assumes fin: "finite A"
urbanc@36079
  1733
 and   empty: "P {}" 
urbanc@36079
  1734
 and  insert: "(!!b A. finite A \<Longrightarrow> ALL a:A. a < b \<Longrightarrow> P A \<Longrightarrow> P(insert b A))"
urbanc@36079
  1735
 shows "P A"
urbanc@36079
  1736
using fin empty insert
nipkow@32006
  1737
proof (induct rule: finite_psubset_induct)
urbanc@36079
  1738
  case (psubset A)
urbanc@36079
  1739
  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 
urbanc@36079
  1740
  have fin: "finite A" by fact 
urbanc@36079
  1741
  have empty: "P {}" by fact
urbanc@36079
  1742
  have step: "\<And>b A. \<lbrakk>finite A; \<forall>a\<in>A. a < b; P A\<rbrakk> \<Longrightarrow> P (insert b A)" by fact
krauss@26748
  1743
  show "P A"
haftmann@26757
  1744
  proof (cases "A = {}")
urbanc@36079
  1745
    assume "A = {}" 
urbanc@36079
  1746
    then show "P A" using `P {}` by simp
krauss@26748
  1747
  next
urbanc@36079
  1748
    let ?B = "A - {Max A}" 
urbanc@36079
  1749
    let ?A = "insert (Max A) ?B"
urbanc@36079
  1750
    have "finite ?B" using `finite A` by simp
krauss@26748
  1751
    assume "A \<noteq> {}"
krauss@26748
  1752
    with `finite A` have "Max A : A" by auto
urbanc@36079
  1753
    then have A: "?A = A" using insert_Diff_single insert_absorb by auto
urbanc@36079
  1754
    then have "P ?B" using `P {}` step IH[of ?B] by blast
urbanc@36079
  1755
    moreover 
nipkow@44890
  1756
    have "\<forall>a\<in>?B. a < Max A" using Max_ge [OF `finite A`] by fastforce
nipkow@44890
  1757
    ultimately show "P A" using A insert_Diff_single step[OF `finite ?B`] by fastforce
krauss@26748
  1758
  qed
krauss@26748
  1759
qed
krauss@26748
  1760
nipkow@32006
  1761
lemma finite_linorder_min_induct[consumes 1, case_names empty insert]:
nipkow@33434
  1762
 "\<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"
nipkow@32006
  1763
by(rule linorder.finite_linorder_max_induct[OF dual_linorder])
nipkow@32006
  1764
haftmann@22917
  1765
end
haftmann@22917
  1766
haftmann@35028
  1767
context linordered_ab_semigroup_add
haftmann@22917
  1768
begin
haftmann@22917
  1769
haftmann@22917
  1770
lemma add_Min_commute:
haftmann@22917
  1771
  fixes k
haftmann@25062
  1772
  assumes "finite N" and "N \<noteq> {}"
haftmann@25062
  1773
  shows "k + Min N = Min {k + m | m. m \<in> N}"
haftmann@25062
  1774
proof -
haftmann@25062
  1775
  have "\<And>x y. k + min x y = min (k + x) (k + y)"
haftmann@25062
  1776
    by (simp add: min_def not_le)
haftmann@25062
  1777
      (blast intro: antisym less_imp_le add_left_mono)
haftmann@25062
  1778
  with assms show ?thesis
haftmann@25062
  1779
    using hom_Min_commute [of "plus k" N]
haftmann@25062
  1780
    by simp (blast intro: arg_cong [where f = Min])
haftmann@25062
  1781
qed
haftmann@22917
  1782
haftmann@22917
  1783
lemma add_Max_commute:
haftmann@22917
  1784
  fixes k
haftmann@25062
  1785
  assumes "finite N" and "N \<noteq> {}"
haftmann@25062
  1786
  shows "k + Max N = Max {k + m | m. m \<in> N}"
haftmann@25062
  1787
proof -
haftmann@25062
  1788
  have "\<And>x y. k + max x y = max (k + x) (k + y)"
haftmann@25062
  1789
    by (simp add: max_def not_le)
haftmann@25062
  1790
      (blast intro: antisym less_imp_le add_left_mono)
haftmann@25062
  1791
  with assms show ?thesis
haftmann@25062
  1792
    using hom_Max_commute [of "plus k" N]
haftmann@25062
  1793
    by simp (blast intro: arg_cong [where f = Max])
haftmann@25062
  1794
qed
haftmann@22917
  1795
haftmann@22917
  1796
end
haftmann@22917
  1797
haftmann@35034
  1798
context linordered_ab_group_add
haftmann@35034
  1799
begin
haftmann@35034
  1800
haftmann@35034
  1801
lemma minus_Max_eq_Min [simp]:
haftmann@35034
  1802
  "finite S \<Longrightarrow> S \<noteq> {} \<Longrightarrow> - (Max S) = Min (uminus ` S)"
haftmann@35034
  1803
  by (induct S rule: finite_ne_induct) (simp_all add: minus_max_eq_min)
haftmann@35034
  1804
haftmann@35034
  1805
lemma minus_Min_eq_Max [simp]:
haftmann@35034
  1806
  "finite S \<Longrightarrow> S \<noteq> {} \<Longrightarrow> - (Min S) = Max (uminus ` S)"
haftmann@35034
  1807
  by (induct S rule: finite_ne_induct) (simp_all add: minus_min_eq_max)
haftmann@35034
  1808
haftmann@35034
  1809
end
haftmann@35034
  1810
haftmann@51263
  1811
lemma (in linorder) mono_Max_commute:
haftmann@51263
  1812
  assumes "mono f"
haftmann@51263
  1813
  assumes "finite A" and "A \<noteq> {}"
haftmann@51263
  1814
  shows "f (Max A) = Max (f ` A)"
haftmann@51263
  1815
proof (rule linorder_class.Max_eqI [symmetric])
haftmann@51263
  1816
  from `finite A` show "finite (f ` A)" by simp
haftmann@51263
  1817
  from assms show "f (Max A) \<in> f ` A" by simp
haftmann@51263
  1818
  fix x
haftmann@51263
  1819
  assume "x \<in> f ` A"
haftmann@51263
  1820
  then obtain y where "y \<in> A" and "x = f y" ..
haftmann@51263
  1821
  with assms have "y \<le> Max A" by auto
haftmann@51263
  1822
  with `mono f` have "f y \<le> f (Max A)" by (rule monoE)
haftmann@51263
  1823
  with `x = f y` show "x \<le> f (Max A)" by simp
haftmann@51263
  1824
qed (* FIXME augment also dual rule mono_Min_commute *)
haftmann@51263
  1825
haftmann@25571
  1826
end
haftmann@51263
  1827