clasohm@1475
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(* Title: HOL/Fun.thy
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clasohm@1475
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Author: Tobias Nipkow, Cambridge University Computer Laboratory
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clasohm@923
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Copyright 1994 University of Cambridge
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huffman@18154
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*)
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clasohm@923
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huffman@18154
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header {* Notions about functions *}
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clasohm@923
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paulson@15510
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theory Fun
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haftmann@22886
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imports Set
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nipkow@15131
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begin
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nipkow@2912
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haftmann@26147
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text{*As a simplification rule, it replaces all function equalities by
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haftmann@26147
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first-order equalities.*}
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haftmann@26147
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lemma expand_fun_eq: "f = g \<longleftrightarrow> (\<forall>x. f x = g x)"
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haftmann@26147
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apply (rule iffI)
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haftmann@26147
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apply (simp (no_asm_simp))
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haftmann@26147
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apply (rule ext)
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haftmann@26147
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apply (simp (no_asm_simp))
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haftmann@26147
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done
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paulson@6171
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haftmann@26147
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lemma apply_inverse:
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haftmann@26357
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"f x = u \<Longrightarrow> (\<And>x. P x \<Longrightarrow> g (f x) = x) \<Longrightarrow> P x \<Longrightarrow> x = g u"
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haftmann@26147
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by auto
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oheimb@5305
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nipkow@2912
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haftmann@26147
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subsection {* The Identity Function @{text id} *}
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nipkow@2912
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haftmann@22744
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definition
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haftmann@22744
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id :: "'a \<Rightarrow> 'a"
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haftmann@22744
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where
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haftmann@22744
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"id = (\<lambda>x. x)"
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nipkow@13910
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haftmann@26147
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lemma id_apply [simp]: "id x = x"
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haftmann@26147
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by (simp add: id_def)
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haftmann@26147
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haftmann@26147
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lemma image_ident [simp]: "(%x. x) ` Y = Y"
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haftmann@26147
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by blast
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haftmann@26147
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haftmann@26147
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lemma image_id [simp]: "id ` Y = Y"
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haftmann@26147
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by (simp add: id_def)
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haftmann@26147
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haftmann@26147
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lemma vimage_ident [simp]: "(%x. x) -` Y = Y"
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haftmann@26147
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by blast
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haftmann@26147
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haftmann@26147
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lemma vimage_id [simp]: "id -` A = A"
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haftmann@26147
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by (simp add: id_def)
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haftmann@26147
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haftmann@26147
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haftmann@26147
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subsection {* The Composition Operator @{text "f \<circ> g"} *}
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haftmann@26147
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haftmann@22744
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definition
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haftmann@22744
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comp :: "('b \<Rightarrow> 'c) \<Rightarrow> ('a \<Rightarrow> 'b) \<Rightarrow> 'a \<Rightarrow> 'c" (infixl "o" 55)
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haftmann@22744
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where
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haftmann@22744
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"f o g = (\<lambda>x. f (g x))"
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oheimb@11123
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wenzelm@21210
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notation (xsymbols)
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wenzelm@19656
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comp (infixl "\<circ>" 55)
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wenzelm@19656
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wenzelm@21210
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notation (HTML output)
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wenzelm@19656
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comp (infixl "\<circ>" 55)
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wenzelm@19656
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paulson@13585
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text{*compatibility*}
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lemmas o_def = comp_def
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paulson@13585
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paulson@13585
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lemma o_apply [simp]: "(f o g) x = f (g x)"
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paulson@13585
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by (simp add: comp_def)
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paulson@13585
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paulson@13585
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lemma o_assoc: "f o (g o h) = f o g o h"
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paulson@13585
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by (simp add: comp_def)
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paulson@13585
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paulson@13585
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lemma id_o [simp]: "id o g = g"
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paulson@13585
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by (simp add: comp_def)
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paulson@13585
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paulson@13585
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lemma o_id [simp]: "f o id = f"
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paulson@13585
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by (simp add: comp_def)
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paulson@13585
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paulson@13585
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lemma image_compose: "(f o g) ` r = f`(g`r)"
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paulson@13585
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by (simp add: comp_def, blast)
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paulson@13585
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paulson@13585
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lemma UN_o: "UNION A (g o f) = UNION (f`A) g"
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paulson@13585
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by (unfold comp_def, blast)
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paulson@13585
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paulson@13585
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haftmann@26588
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subsection {* The Forward Composition Operator @{text fcomp} *}
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haftmann@26357
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haftmann@26357
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definition
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haftmann@26357
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fcomp :: "('a \<Rightarrow> 'b) \<Rightarrow> ('b \<Rightarrow> 'c) \<Rightarrow> 'a \<Rightarrow> 'c" (infixl "o>" 60)
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haftmann@26357
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where
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haftmann@26357
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"f o> g = (\<lambda>x. g (f x))"
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haftmann@26357
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haftmann@26357
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lemma fcomp_apply: "(f o> g) x = g (f x)"
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haftmann@26357
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by (simp add: fcomp_def)
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haftmann@26357
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haftmann@26357
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lemma fcomp_assoc: "(f o> g) o> h = f o> (g o> h)"
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haftmann@26357
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by (simp add: fcomp_def)
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haftmann@26357
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haftmann@26357
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lemma id_fcomp [simp]: "id o> g = g"
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haftmann@26357
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by (simp add: fcomp_def)
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haftmann@26357
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haftmann@26357
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lemma fcomp_id [simp]: "f o> id = f"
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haftmann@26357
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by (simp add: fcomp_def)
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haftmann@26357
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haftmann@31202
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code_const fcomp
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haftmann@31202
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(Eval infixl 1 "#>")
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haftmann@31202
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haftmann@26588
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no_notation fcomp (infixl "o>" 60)
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haftmann@26588
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haftmann@26357
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haftmann@26147
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subsection {* Injectivity and Surjectivity *}
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paulson@13585
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haftmann@26147
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constdefs
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haftmann@26147
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inj_on :: "['a => 'b, 'a set] => bool" -- "injective"
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haftmann@26147
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"inj_on f A == ! x:A. ! y:A. f(x)=f(y) --> x=y"
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paulson@13585
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haftmann@26147
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text{*A common special case: functions injective over the entire domain type.*}
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haftmann@26147
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haftmann@26147
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abbreviation
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haftmann@26147
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"inj f == inj_on f UNIV"
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haftmann@26147
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haftmann@26147
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definition
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haftmann@26147
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bij_betw :: "('a => 'b) => 'a set => 'b set => bool" where -- "bijective"
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haftmann@28562
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[code del]: "bij_betw f A B \<longleftrightarrow> inj_on f A & f ` A = B"
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haftmann@26147
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haftmann@26147
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constdefs
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haftmann@26147
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surj :: "('a => 'b) => bool" (*surjective*)
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haftmann@26147
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"surj f == ! y. ? x. y=f(x)"
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haftmann@26147
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haftmann@26147
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bij :: "('a => 'b) => bool" (*bijective*)
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haftmann@26147
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"bij f == inj f & surj f"
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haftmann@26147
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haftmann@26147
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lemma injI:
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haftmann@26147
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assumes "\<And>x y. f x = f y \<Longrightarrow> x = y"
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haftmann@26147
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shows "inj f"
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haftmann@26147
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using assms unfolding inj_on_def by auto
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paulson@13585
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paulson@13585
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text{*For Proofs in @{text "Tools/datatype_rep_proofs"}*}
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paulson@13585
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lemma datatype_injI:
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paulson@13585
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"(!! x. ALL y. f(x) = f(y) --> x=y) ==> inj(f)"
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paulson@13585
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by (simp add: inj_on_def)
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paulson@13585
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berghofe@13637
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theorem range_ex1_eq: "inj f \<Longrightarrow> b : range f = (EX! x. b = f x)"
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berghofe@13637
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by (unfold inj_on_def, blast)
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berghofe@13637
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paulson@13585
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lemma injD: "[| inj(f); f(x) = f(y) |] ==> x=y"
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paulson@13585
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by (simp add: inj_on_def)
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paulson@13585
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paulson@13585
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(*Useful with the simplifier*)
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paulson@13585
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lemma inj_eq: "inj(f) ==> (f(x) = f(y)) = (x=y)"
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paulson@13585
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by (force simp add: inj_on_def)
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paulson@13585
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haftmann@26147
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lemma inj_on_id[simp]: "inj_on id A"
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haftmann@26147
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by (simp add: inj_on_def)
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paulson@13585
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haftmann@26147
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lemma inj_on_id2[simp]: "inj_on (%x. x) A"
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haftmann@26147
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by (simp add: inj_on_def)
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haftmann@26147
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haftmann@26147
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lemma surj_id[simp]: "surj id"
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haftmann@26147
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by (simp add: surj_def)
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haftmann@26147
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haftmann@26147
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lemma bij_id[simp]: "bij id"
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haftmann@26147
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by (simp add: bij_def inj_on_id surj_id)
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paulson@13585
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paulson@13585
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lemma inj_onI:
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paulson@13585
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"(!! x y. [| x:A; y:A; f(x) = f(y) |] ==> x=y) ==> inj_on f A"
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paulson@13585
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by (simp add: inj_on_def)
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paulson@13585
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paulson@13585
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lemma inj_on_inverseI: "(!!x. x:A ==> g(f(x)) = x) ==> inj_on f A"
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paulson@13585
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by (auto dest: arg_cong [of concl: g] simp add: inj_on_def)
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paulson@13585
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paulson@13585
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lemma inj_onD: "[| inj_on f A; f(x)=f(y); x:A; y:A |] ==> x=y"
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paulson@13585
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by (unfold inj_on_def, blast)
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paulson@13585
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paulson@13585
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lemma inj_on_iff: "[| inj_on f A; x:A; y:A |] ==> (f(x)=f(y)) = (x=y)"
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paulson@13585
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by (blast dest!: inj_onD)
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paulson@13585
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paulson@13585
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lemma comp_inj_on:
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paulson@13585
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"[| inj_on f A; inj_on g (f`A) |] ==> inj_on (g o f) A"
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paulson@13585
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by (simp add: comp_def inj_on_def)
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paulson@13585
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nipkow@15303
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lemma inj_on_imageI: "inj_on (g o f) A \<Longrightarrow> inj_on g (f ` A)"
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nipkow@15303
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apply(simp add:inj_on_def image_def)
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nipkow@15303
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apply blast
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nipkow@15303
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done
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nipkow@15303
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nipkow@15439
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lemma inj_on_image_iff: "\<lbrakk> ALL x:A. ALL y:A. (g(f x) = g(f y)) = (g x = g y);
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nipkow@15439
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inj_on f A \<rbrakk> \<Longrightarrow> inj_on g (f ` A) = inj_on g A"
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nipkow@15439
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apply(unfold inj_on_def)
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nipkow@15439
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apply blast
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nipkow@15439
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done
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nipkow@15439
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paulson@13585
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lemma inj_on_contraD: "[| inj_on f A; ~x=y; x:A; y:A |] ==> ~ f(x)=f(y)"
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paulson@13585
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by (unfold inj_on_def, blast)
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paulson@13585
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paulson@13585
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lemma inj_singleton: "inj (%s. {s})"
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paulson@13585
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by (simp add: inj_on_def)
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paulson@13585
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nipkow@15111
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lemma inj_on_empty[iff]: "inj_on f {}"
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nipkow@15111
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by(simp add: inj_on_def)
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nipkow@15111
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nipkow@15303
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lemma subset_inj_on: "[| inj_on f B; A <= B |] ==> inj_on f A"
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paulson@13585
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by (unfold inj_on_def, blast)
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paulson@13585
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nipkow@15111
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lemma inj_on_Un:
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nipkow@15111
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"inj_on f (A Un B) =
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nipkow@15111
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(inj_on f A & inj_on f B & f`(A-B) Int f`(B-A) = {})"
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nipkow@15111
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apply(unfold inj_on_def)
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nipkow@15111
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apply (blast intro:sym)
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nipkow@15111
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done
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nipkow@15111
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nipkow@15111
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lemma inj_on_insert[iff]:
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nipkow@15111
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"inj_on f (insert a A) = (inj_on f A & f a ~: f`(A-{a}))"
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nipkow@15111
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apply(unfold inj_on_def)
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nipkow@15111
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apply (blast intro:sym)
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nipkow@15111
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done
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nipkow@15111
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nipkow@15111
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lemma inj_on_diff: "inj_on f A ==> inj_on f (A-B)"
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nipkow@15111
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apply(unfold inj_on_def)
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nipkow@15111
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apply (blast)
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nipkow@15111
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219 |
done
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nipkow@15111
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220 |
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paulson@13585
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lemma surjI: "(!! x. g(f x) = x) ==> surj g"
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paulson@13585
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apply (simp add: surj_def)
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paulson@13585
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apply (blast intro: sym)
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paulson@13585
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224 |
done
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paulson@13585
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225 |
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paulson@13585
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226 |
lemma surj_range: "surj f ==> range f = UNIV"
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paulson@13585
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227 |
by (auto simp add: surj_def)
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paulson@13585
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228 |
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paulson@13585
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229 |
lemma surjD: "surj f ==> EX x. y = f x"
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paulson@13585
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by (simp add: surj_def)
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paulson@13585
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paulson@13585
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lemma surjE: "surj f ==> (!!x. y = f x ==> C) ==> C"
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paulson@13585
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by (simp add: surj_def, blast)
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paulson@13585
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234 |
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paulson@13585
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lemma comp_surj: "[| surj f; surj g |] ==> surj (g o f)"
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paulson@13585
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236 |
apply (simp add: comp_def surj_def, clarify)
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paulson@13585
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237 |
apply (drule_tac x = y in spec, clarify)
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paulson@13585
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238 |
apply (drule_tac x = x in spec, blast)
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paulson@13585
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239 |
done
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paulson@13585
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240 |
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paulson@13585
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241 |
lemma bijI: "[| inj f; surj f |] ==> bij f"
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paulson@13585
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242 |
by (simp add: bij_def)
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paulson@13585
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243 |
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paulson@13585
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244 |
lemma bij_is_inj: "bij f ==> inj f"
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paulson@13585
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245 |
by (simp add: bij_def)
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paulson@13585
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246 |
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paulson@13585
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247 |
lemma bij_is_surj: "bij f ==> surj f"
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paulson@13585
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248 |
by (simp add: bij_def)
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paulson@13585
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249 |
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nipkow@26105
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250 |
lemma bij_betw_imp_inj_on: "bij_betw f A B \<Longrightarrow> inj_on f A"
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nipkow@26105
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251 |
by (simp add: bij_betw_def)
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nipkow@26105
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252 |
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nipkow@26105
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253 |
lemma bij_betw_inv: assumes "bij_betw f A B" shows "EX g. bij_betw g B A"
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nipkow@26105
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254 |
proof -
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nipkow@26105
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255 |
have i: "inj_on f A" and s: "f ` A = B"
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nipkow@26105
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256 |
using assms by(auto simp:bij_betw_def)
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nipkow@26105
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257 |
let ?P = "%b a. a:A \<and> f a = b" let ?g = "%b. The (?P b)"
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nipkow@26105
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{ fix a b assume P: "?P b a"
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nipkow@26105
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259 |
hence ex1: "\<exists>a. ?P b a" using s unfolding image_def by blast
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nipkow@26105
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260 |
hence uex1: "\<exists>!a. ?P b a" by(blast dest:inj_onD[OF i])
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nipkow@26105
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261 |
hence " ?g b = a" using the1_equality[OF uex1, OF P] P by simp
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nipkow@26105
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262 |
} note g = this
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nipkow@26105
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263 |
have "inj_on ?g B"
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nipkow@26105
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264 |
proof(rule inj_onI)
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nipkow@26105
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265 |
fix x y assume "x:B" "y:B" "?g x = ?g y"
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nipkow@26105
|
266 |
from s `x:B` obtain a1 where a1: "?P x a1" unfolding image_def by blast
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nipkow@26105
|
267 |
from s `y:B` obtain a2 where a2: "?P y a2" unfolding image_def by blast
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nipkow@26105
|
268 |
from g[OF a1] a1 g[OF a2] a2 `?g x = ?g y` show "x=y" by simp
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nipkow@26105
|
269 |
qed
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nipkow@26105
|
270 |
moreover have "?g ` B = A"
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nipkow@26105
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271 |
proof(auto simp:image_def)
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nipkow@26105
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272 |
fix b assume "b:B"
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nipkow@26105
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273 |
with s obtain a where P: "?P b a" unfolding image_def by blast
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nipkow@26105
|
274 |
thus "?g b \<in> A" using g[OF P] by auto
|
nipkow@26105
|
275 |
next
|
nipkow@26105
|
276 |
fix a assume "a:A"
|
nipkow@26105
|
277 |
then obtain b where P: "?P b a" using s unfolding image_def by blast
|
nipkow@26105
|
278 |
then have "b:B" using s unfolding image_def by blast
|
nipkow@26105
|
279 |
with g[OF P] show "\<exists>b\<in>B. a = ?g b" by blast
|
nipkow@26105
|
280 |
qed
|
nipkow@26105
|
281 |
ultimately show ?thesis by(auto simp:bij_betw_def)
|
nipkow@26105
|
282 |
qed
|
nipkow@26105
|
283 |
|
paulson@13585
|
284 |
lemma surj_image_vimage_eq: "surj f ==> f ` (f -` A) = A"
|
paulson@13585
|
285 |
by (simp add: surj_range)
|
paulson@13585
|
286 |
|
paulson@13585
|
287 |
lemma inj_vimage_image_eq: "inj f ==> f -` (f ` A) = A"
|
paulson@13585
|
288 |
by (simp add: inj_on_def, blast)
|
paulson@13585
|
289 |
|
paulson@13585
|
290 |
lemma vimage_subsetD: "surj f ==> f -` B <= A ==> B <= f ` A"
|
paulson@13585
|
291 |
apply (unfold surj_def)
|
paulson@13585
|
292 |
apply (blast intro: sym)
|
paulson@13585
|
293 |
done
|
paulson@13585
|
294 |
|
paulson@13585
|
295 |
lemma vimage_subsetI: "inj f ==> B <= f ` A ==> f -` B <= A"
|
paulson@13585
|
296 |
by (unfold inj_on_def, blast)
|
paulson@13585
|
297 |
|
paulson@13585
|
298 |
lemma vimage_subset_eq: "bij f ==> (f -` B <= A) = (B <= f ` A)"
|
paulson@13585
|
299 |
apply (unfold bij_def)
|
paulson@13585
|
300 |
apply (blast del: subsetI intro: vimage_subsetI vimage_subsetD)
|
paulson@13585
|
301 |
done
|
paulson@13585
|
302 |
|
paulson@13585
|
303 |
lemma inj_on_image_Int:
|
paulson@13585
|
304 |
"[| inj_on f C; A<=C; B<=C |] ==> f`(A Int B) = f`A Int f`B"
|
paulson@13585
|
305 |
apply (simp add: inj_on_def, blast)
|
paulson@13585
|
306 |
done
|
paulson@13585
|
307 |
|
paulson@13585
|
308 |
lemma inj_on_image_set_diff:
|
paulson@13585
|
309 |
"[| inj_on f C; A<=C; B<=C |] ==> f`(A-B) = f`A - f`B"
|
paulson@13585
|
310 |
apply (simp add: inj_on_def, blast)
|
paulson@13585
|
311 |
done
|
paulson@13585
|
312 |
|
paulson@13585
|
313 |
lemma image_Int: "inj f ==> f`(A Int B) = f`A Int f`B"
|
paulson@13585
|
314 |
by (simp add: inj_on_def, blast)
|
paulson@13585
|
315 |
|
paulson@13585
|
316 |
lemma image_set_diff: "inj f ==> f`(A-B) = f`A - f`B"
|
paulson@13585
|
317 |
by (simp add: inj_on_def, blast)
|
paulson@13585
|
318 |
|
paulson@13585
|
319 |
lemma inj_image_mem_iff: "inj f ==> (f a : f`A) = (a : A)"
|
paulson@13585
|
320 |
by (blast dest: injD)
|
paulson@13585
|
321 |
|
paulson@13585
|
322 |
lemma inj_image_subset_iff: "inj f ==> (f`A <= f`B) = (A<=B)"
|
paulson@13585
|
323 |
by (simp add: inj_on_def, blast)
|
paulson@13585
|
324 |
|
paulson@13585
|
325 |
lemma inj_image_eq_iff: "inj f ==> (f`A = f`B) = (A = B)"
|
paulson@13585
|
326 |
by (blast dest: injD)
|
paulson@13585
|
327 |
|
paulson@13585
|
328 |
(*injectivity's required. Left-to-right inclusion holds even if A is empty*)
|
paulson@13585
|
329 |
lemma image_INT:
|
paulson@13585
|
330 |
"[| inj_on f C; ALL x:A. B x <= C; j:A |]
|
paulson@13585
|
331 |
==> f ` (INTER A B) = (INT x:A. f ` B x)"
|
paulson@13585
|
332 |
apply (simp add: inj_on_def, blast)
|
paulson@13585
|
333 |
done
|
paulson@13585
|
334 |
|
paulson@13585
|
335 |
(*Compare with image_INT: no use of inj_on, and if f is surjective then
|
paulson@13585
|
336 |
it doesn't matter whether A is empty*)
|
paulson@13585
|
337 |
lemma bij_image_INT: "bij f ==> f ` (INTER A B) = (INT x:A. f ` B x)"
|
paulson@13585
|
338 |
apply (simp add: bij_def)
|
paulson@13585
|
339 |
apply (simp add: inj_on_def surj_def, blast)
|
paulson@13585
|
340 |
done
|
paulson@13585
|
341 |
|
paulson@13585
|
342 |
lemma surj_Compl_image_subset: "surj f ==> -(f`A) <= f`(-A)"
|
paulson@13585
|
343 |
by (auto simp add: surj_def)
|
paulson@13585
|
344 |
|
paulson@13585
|
345 |
lemma inj_image_Compl_subset: "inj f ==> f`(-A) <= -(f`A)"
|
paulson@13585
|
346 |
by (auto simp add: inj_on_def)
|
paulson@13585
|
347 |
|
paulson@13585
|
348 |
lemma bij_image_Compl_eq: "bij f ==> f`(-A) = -(f`A)"
|
paulson@13585
|
349 |
apply (simp add: bij_def)
|
paulson@13585
|
350 |
apply (rule equalityI)
|
paulson@13585
|
351 |
apply (simp_all (no_asm_simp) add: inj_image_Compl_subset surj_Compl_image_subset)
|
paulson@13585
|
352 |
done
|
paulson@13585
|
353 |
|
paulson@13585
|
354 |
|
paulson@13585
|
355 |
subsection{*Function Updating*}
|
paulson@13585
|
356 |
|
haftmann@26147
|
357 |
constdefs
|
haftmann@26147
|
358 |
fun_upd :: "('a => 'b) => 'a => 'b => ('a => 'b)"
|
haftmann@26147
|
359 |
"fun_upd f a b == % x. if x=a then b else f x"
|
haftmann@26147
|
360 |
|
haftmann@26147
|
361 |
nonterminals
|
haftmann@26147
|
362 |
updbinds updbind
|
haftmann@26147
|
363 |
syntax
|
haftmann@26147
|
364 |
"_updbind" :: "['a, 'a] => updbind" ("(2_ :=/ _)")
|
haftmann@26147
|
365 |
"" :: "updbind => updbinds" ("_")
|
haftmann@26147
|
366 |
"_updbinds":: "[updbind, updbinds] => updbinds" ("_,/ _")
|
haftmann@26147
|
367 |
"_Update" :: "['a, updbinds] => 'a" ("_/'((_)')" [1000,0] 900)
|
haftmann@26147
|
368 |
|
haftmann@26147
|
369 |
translations
|
haftmann@26147
|
370 |
"_Update f (_updbinds b bs)" == "_Update (_Update f b) bs"
|
haftmann@26147
|
371 |
"f(x:=y)" == "fun_upd f x y"
|
haftmann@26147
|
372 |
|
haftmann@26147
|
373 |
(* Hint: to define the sum of two functions (or maps), use sum_case.
|
haftmann@26147
|
374 |
A nice infix syntax could be defined (in Datatype.thy or below) by
|
haftmann@26147
|
375 |
consts
|
haftmann@26147
|
376 |
fun_sum :: "('a => 'c) => ('b => 'c) => (('a+'b) => 'c)" (infixr "'(+')"80)
|
haftmann@26147
|
377 |
translations
|
haftmann@26147
|
378 |
"fun_sum" == sum_case
|
haftmann@26147
|
379 |
*)
|
haftmann@26147
|
380 |
|
paulson@13585
|
381 |
lemma fun_upd_idem_iff: "(f(x:=y) = f) = (f x = y)"
|
paulson@13585
|
382 |
apply (simp add: fun_upd_def, safe)
|
paulson@13585
|
383 |
apply (erule subst)
|
paulson@13585
|
384 |
apply (rule_tac [2] ext, auto)
|
paulson@13585
|
385 |
done
|
paulson@13585
|
386 |
|
paulson@13585
|
387 |
(* f x = y ==> f(x:=y) = f *)
|
paulson@13585
|
388 |
lemmas fun_upd_idem = fun_upd_idem_iff [THEN iffD2, standard]
|
paulson@13585
|
389 |
|
paulson@13585
|
390 |
(* f(x := f x) = f *)
|
paulson@17084
|
391 |
lemmas fun_upd_triv = refl [THEN fun_upd_idem]
|
paulson@17084
|
392 |
declare fun_upd_triv [iff]
|
paulson@13585
|
393 |
|
paulson@13585
|
394 |
lemma fun_upd_apply [simp]: "(f(x:=y))z = (if z=x then y else f z)"
|
paulson@17084
|
395 |
by (simp add: fun_upd_def)
|
paulson@13585
|
396 |
|
paulson@13585
|
397 |
(* fun_upd_apply supersedes these two, but they are useful
|
paulson@13585
|
398 |
if fun_upd_apply is intentionally removed from the simpset *)
|
paulson@13585
|
399 |
lemma fun_upd_same: "(f(x:=y)) x = y"
|
paulson@13585
|
400 |
by simp
|
paulson@13585
|
401 |
|
paulson@13585
|
402 |
lemma fun_upd_other: "z~=x ==> (f(x:=y)) z = f z"
|
paulson@13585
|
403 |
by simp
|
paulson@13585
|
404 |
|
paulson@13585
|
405 |
lemma fun_upd_upd [simp]: "f(x:=y,x:=z) = f(x:=z)"
|
paulson@13585
|
406 |
by (simp add: expand_fun_eq)
|
paulson@13585
|
407 |
|
paulson@13585
|
408 |
lemma fun_upd_twist: "a ~= c ==> (m(a:=b))(c:=d) = (m(c:=d))(a:=b)"
|
paulson@13585
|
409 |
by (rule ext, auto)
|
paulson@13585
|
410 |
|
nipkow@15303
|
411 |
lemma inj_on_fun_updI: "\<lbrakk> inj_on f A; y \<notin> f`A \<rbrakk> \<Longrightarrow> inj_on (f(x:=y)) A"
|
nipkow@15303
|
412 |
by(fastsimp simp:inj_on_def image_def)
|
nipkow@15303
|
413 |
|
paulson@15510
|
414 |
lemma fun_upd_image:
|
paulson@15510
|
415 |
"f(x:=y) ` A = (if x \<in> A then insert y (f ` (A-{x})) else f ` A)"
|
paulson@15510
|
416 |
by auto
|
paulson@15510
|
417 |
|
nipkow@31080
|
418 |
lemma fun_upd_comp: "f \<circ> (g(x := y)) = (f \<circ> g)(x := f y)"
|
nipkow@31080
|
419 |
by(auto intro: ext)
|
nipkow@31080
|
420 |
|
haftmann@26147
|
421 |
|
haftmann@26147
|
422 |
subsection {* @{text override_on} *}
|
haftmann@26147
|
423 |
|
haftmann@26147
|
424 |
definition
|
haftmann@26147
|
425 |
override_on :: "('a \<Rightarrow> 'b) \<Rightarrow> ('a \<Rightarrow> 'b) \<Rightarrow> 'a set \<Rightarrow> 'a \<Rightarrow> 'b"
|
haftmann@26147
|
426 |
where
|
haftmann@26147
|
427 |
"override_on f g A = (\<lambda>a. if a \<in> A then g a else f a)"
|
nipkow@13910
|
428 |
|
nipkow@15691
|
429 |
lemma override_on_emptyset[simp]: "override_on f g {} = f"
|
nipkow@15691
|
430 |
by(simp add:override_on_def)
|
nipkow@13910
|
431 |
|
nipkow@15691
|
432 |
lemma override_on_apply_notin[simp]: "a ~: A ==> (override_on f g A) a = f a"
|
nipkow@15691
|
433 |
by(simp add:override_on_def)
|
nipkow@13910
|
434 |
|
nipkow@15691
|
435 |
lemma override_on_apply_in[simp]: "a : A ==> (override_on f g A) a = g a"
|
nipkow@15691
|
436 |
by(simp add:override_on_def)
|
nipkow@13910
|
437 |
|
haftmann@26147
|
438 |
|
haftmann@26147
|
439 |
subsection {* @{text swap} *}
|
paulson@15510
|
440 |
|
haftmann@22744
|
441 |
definition
|
haftmann@22744
|
442 |
swap :: "'a \<Rightarrow> 'a \<Rightarrow> ('a \<Rightarrow> 'b) \<Rightarrow> ('a \<Rightarrow> 'b)"
|
haftmann@22744
|
443 |
where
|
haftmann@22744
|
444 |
"swap a b f = f (a := f b, b:= f a)"
|
paulson@15510
|
445 |
|
paulson@15510
|
446 |
lemma swap_self: "swap a a f = f"
|
nipkow@15691
|
447 |
by (simp add: swap_def)
|
paulson@15510
|
448 |
|
paulson@15510
|
449 |
lemma swap_commute: "swap a b f = swap b a f"
|
paulson@15510
|
450 |
by (rule ext, simp add: fun_upd_def swap_def)
|
paulson@15510
|
451 |
|
paulson@15510
|
452 |
lemma swap_nilpotent [simp]: "swap a b (swap a b f) = f"
|
paulson@15510
|
453 |
by (rule ext, simp add: fun_upd_def swap_def)
|
paulson@15510
|
454 |
|
paulson@15510
|
455 |
lemma inj_on_imp_inj_on_swap:
|
haftmann@22744
|
456 |
"[|inj_on f A; a \<in> A; b \<in> A|] ==> inj_on (swap a b f) A"
|
paulson@15510
|
457 |
by (simp add: inj_on_def swap_def, blast)
|
paulson@15510
|
458 |
|
paulson@15510
|
459 |
lemma inj_on_swap_iff [simp]:
|
paulson@15510
|
460 |
assumes A: "a \<in> A" "b \<in> A" shows "inj_on (swap a b f) A = inj_on f A"
|
paulson@15510
|
461 |
proof
|
paulson@15510
|
462 |
assume "inj_on (swap a b f) A"
|
paulson@15510
|
463 |
with A have "inj_on (swap a b (swap a b f)) A"
|
nipkow@17589
|
464 |
by (iprover intro: inj_on_imp_inj_on_swap)
|
paulson@15510
|
465 |
thus "inj_on f A" by simp
|
paulson@15510
|
466 |
next
|
paulson@15510
|
467 |
assume "inj_on f A"
|
nipkow@27165
|
468 |
with A show "inj_on (swap a b f) A" by(iprover intro: inj_on_imp_inj_on_swap)
|
paulson@15510
|
469 |
qed
|
paulson@15510
|
470 |
|
paulson@15510
|
471 |
lemma surj_imp_surj_swap: "surj f ==> surj (swap a b f)"
|
paulson@15510
|
472 |
apply (simp add: surj_def swap_def, clarify)
|
wenzelm@27125
|
473 |
apply (case_tac "y = f b", blast)
|
wenzelm@27125
|
474 |
apply (case_tac "y = f a", auto)
|
paulson@15510
|
475 |
done
|
paulson@15510
|
476 |
|
paulson@15510
|
477 |
lemma surj_swap_iff [simp]: "surj (swap a b f) = surj f"
|
paulson@15510
|
478 |
proof
|
paulson@15510
|
479 |
assume "surj (swap a b f)"
|
paulson@15510
|
480 |
hence "surj (swap a b (swap a b f))" by (rule surj_imp_surj_swap)
|
paulson@15510
|
481 |
thus "surj f" by simp
|
paulson@15510
|
482 |
next
|
paulson@15510
|
483 |
assume "surj f"
|
paulson@15510
|
484 |
thus "surj (swap a b f)" by (rule surj_imp_surj_swap)
|
paulson@15510
|
485 |
qed
|
paulson@15510
|
486 |
|
paulson@15510
|
487 |
lemma bij_swap_iff: "bij (swap a b f) = bij f"
|
paulson@15510
|
488 |
by (simp add: bij_def)
|
haftmann@21547
|
489 |
|
nipkow@27188
|
490 |
hide (open) const swap
|
haftmann@21547
|
491 |
|
haftmann@22845
|
492 |
subsection {* Proof tool setup *}
|
haftmann@22845
|
493 |
|
haftmann@22845
|
494 |
text {* simplifies terms of the form
|
haftmann@22845
|
495 |
f(...,x:=y,...,x:=z,...) to f(...,x:=z,...) *}
|
haftmann@22845
|
496 |
|
wenzelm@24017
|
497 |
simproc_setup fun_upd2 ("f(v := w, x := y)") = {* fn _ =>
|
haftmann@22845
|
498 |
let
|
haftmann@22845
|
499 |
fun gen_fun_upd NONE T _ _ = NONE
|
wenzelm@24017
|
500 |
| gen_fun_upd (SOME f) T x y = SOME (Const (@{const_name fun_upd}, T) $ f $ x $ y)
|
haftmann@22845
|
501 |
fun dest_fun_T1 (Type (_, T :: Ts)) = T
|
haftmann@22845
|
502 |
fun find_double (t as Const (@{const_name fun_upd},T) $ f $ x $ y) =
|
haftmann@22845
|
503 |
let
|
haftmann@22845
|
504 |
fun find (Const (@{const_name fun_upd},T) $ g $ v $ w) =
|
haftmann@22845
|
505 |
if v aconv x then SOME g else gen_fun_upd (find g) T v w
|
haftmann@22845
|
506 |
| find t = NONE
|
haftmann@22845
|
507 |
in (dest_fun_T1 T, gen_fun_upd (find f) T x y) end
|
wenzelm@24017
|
508 |
|
wenzelm@24017
|
509 |
fun proc ss ct =
|
wenzelm@24017
|
510 |
let
|
wenzelm@24017
|
511 |
val ctxt = Simplifier.the_context ss
|
wenzelm@24017
|
512 |
val t = Thm.term_of ct
|
wenzelm@24017
|
513 |
in
|
wenzelm@24017
|
514 |
case find_double t of
|
wenzelm@24017
|
515 |
(T, NONE) => NONE
|
wenzelm@24017
|
516 |
| (T, SOME rhs) =>
|
wenzelm@27330
|
517 |
SOME (Goal.prove ctxt [] [] (Logic.mk_equals (t, rhs))
|
wenzelm@24017
|
518 |
(fn _ =>
|
wenzelm@24017
|
519 |
rtac eq_reflection 1 THEN
|
wenzelm@24017
|
520 |
rtac ext 1 THEN
|
wenzelm@24017
|
521 |
simp_tac (Simplifier.inherit_context ss @{simpset}) 1))
|
wenzelm@24017
|
522 |
end
|
wenzelm@24017
|
523 |
in proc end
|
haftmann@22845
|
524 |
*}
|
haftmann@22845
|
525 |
|
haftmann@22845
|
526 |
|
haftmann@21870
|
527 |
subsection {* Code generator setup *}
|
haftmann@21870
|
528 |
|
berghofe@25886
|
529 |
types_code
|
berghofe@25886
|
530 |
"fun" ("(_ ->/ _)")
|
berghofe@25886
|
531 |
attach (term_of) {*
|
berghofe@25886
|
532 |
fun term_of_fun_type _ aT _ bT _ = Free ("<function>", aT --> bT);
|
berghofe@25886
|
533 |
*}
|
berghofe@25886
|
534 |
attach (test) {*
|
berghofe@25886
|
535 |
fun gen_fun_type aF aT bG bT i =
|
berghofe@25886
|
536 |
let
|
berghofe@25886
|
537 |
val tab = ref [];
|
berghofe@25886
|
538 |
fun mk_upd (x, (_, y)) t = Const ("Fun.fun_upd",
|
berghofe@25886
|
539 |
(aT --> bT) --> aT --> bT --> aT --> bT) $ t $ aF x $ y ()
|
berghofe@25886
|
540 |
in
|
berghofe@25886
|
541 |
(fn x =>
|
berghofe@25886
|
542 |
case AList.lookup op = (!tab) x of
|
berghofe@25886
|
543 |
NONE =>
|
berghofe@25886
|
544 |
let val p as (y, _) = bG i
|
berghofe@25886
|
545 |
in (tab := (x, p) :: !tab; y) end
|
berghofe@25886
|
546 |
| SOME (y, _) => y,
|
berghofe@28711
|
547 |
fn () => Basics.fold mk_upd (!tab) (Const ("HOL.undefined", aT --> bT)))
|
berghofe@25886
|
548 |
end;
|
berghofe@25886
|
549 |
*}
|
berghofe@25886
|
550 |
|
haftmann@21870
|
551 |
code_const "op \<circ>"
|
haftmann@21870
|
552 |
(SML infixl 5 "o")
|
haftmann@21870
|
553 |
(Haskell infixr 9 ".")
|
haftmann@21870
|
554 |
|
haftmann@21906
|
555 |
code_const "id"
|
haftmann@21906
|
556 |
(Haskell "id")
|
haftmann@21906
|
557 |
|
nipkow@2912
|
558 |
end
|