src/HOL/Library/Quotient_Sum.thy
author haftmann
Fri Mar 22 19:18:08 2019 +0000 (4 months ago)
changeset 69946 494934c30f38
parent 67399 eab6ce8368fa
permissions -rw-r--r--
improved code equations taken over from AFP
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(*  Title:      HOL/Library/Quotient_Sum.thy
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    Author:     Cezary Kaliszyk and Christian Urban
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*)
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section \<open>Quotient infrastructure for the sum type\<close>
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theory Quotient_Sum
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imports Quotient_Syntax
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begin
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subsection \<open>Rules for the Quotient package\<close>
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lemma rel_sum_map1:
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  "rel_sum R1 R2 (map_sum f1 f2 x) y \<longleftrightarrow> rel_sum (\<lambda>x. R1 (f1 x)) (\<lambda>x. R2 (f2 x)) x y"
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  by (rule sum.rel_map(1))
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lemma rel_sum_map2:
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  "rel_sum R1 R2 x (map_sum f1 f2 y) \<longleftrightarrow> rel_sum (\<lambda>x y. R1 x (f1 y)) (\<lambda>x y. R2 x (f2 y)) x y"
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  by (rule sum.rel_map(2))
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lemma map_sum_id [id_simps]:
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  "map_sum id id = id"
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  by (simp add: id_def map_sum.identity fun_eq_iff)
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lemma rel_sum_eq [id_simps]:
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  "rel_sum (=) (=) = (=)"
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  by (rule sum.rel_eq)
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lemma reflp_rel_sum:
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  "reflp R1 \<Longrightarrow> reflp R2 \<Longrightarrow> reflp (rel_sum R1 R2)"
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  unfolding reflp_def split_sum_all rel_sum_simps by fast
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lemma sum_symp:
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  "symp R1 \<Longrightarrow> symp R2 \<Longrightarrow> symp (rel_sum R1 R2)"
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  unfolding symp_def split_sum_all rel_sum_simps by fast
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lemma sum_transp:
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  "transp R1 \<Longrightarrow> transp R2 \<Longrightarrow> transp (rel_sum R1 R2)"
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  unfolding transp_def split_sum_all rel_sum_simps by fast
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lemma sum_equivp [quot_equiv]:
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  "equivp R1 \<Longrightarrow> equivp R2 \<Longrightarrow> equivp (rel_sum R1 R2)"
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  by (blast intro: equivpI reflp_rel_sum sum_symp sum_transp elim: equivpE)
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lemma sum_quotient [quot_thm]:
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  assumes q1: "Quotient3 R1 Abs1 Rep1"
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  assumes q2: "Quotient3 R2 Abs2 Rep2"
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  shows "Quotient3 (rel_sum R1 R2) (map_sum Abs1 Abs2) (map_sum Rep1 Rep2)"
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  apply (rule Quotient3I)
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  apply (simp_all add: map_sum.compositionality comp_def map_sum.identity rel_sum_eq rel_sum_map1 rel_sum_map2
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    Quotient3_abs_rep [OF q1] Quotient3_rel_rep [OF q1] Quotient3_abs_rep [OF q2] Quotient3_rel_rep [OF q2])
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  using Quotient3_rel [OF q1] Quotient3_rel [OF q2]
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  apply (fastforce elim!: rel_sum.cases simp add: comp_def split: sum.split)
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  done
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declare [[mapQ3 sum = (rel_sum, sum_quotient)]]
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lemma sum_Inl_rsp [quot_respect]:
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  assumes q1: "Quotient3 R1 Abs1 Rep1"
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  assumes q2: "Quotient3 R2 Abs2 Rep2"
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  shows "(R1 ===> rel_sum R1 R2) Inl Inl"
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  by auto
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lemma sum_Inr_rsp [quot_respect]:
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  assumes q1: "Quotient3 R1 Abs1 Rep1"
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  assumes q2: "Quotient3 R2 Abs2 Rep2"
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  shows "(R2 ===> rel_sum R1 R2) Inr Inr"
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  by auto
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lemma sum_Inl_prs [quot_preserve]:
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  assumes q1: "Quotient3 R1 Abs1 Rep1"
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  assumes q2: "Quotient3 R2 Abs2 Rep2"
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  shows "(Rep1 ---> map_sum Abs1 Abs2) Inl = Inl"
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  apply(simp add: fun_eq_iff)
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  apply(simp add: Quotient3_abs_rep[OF q1])
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  done
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lemma sum_Inr_prs [quot_preserve]:
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  assumes q1: "Quotient3 R1 Abs1 Rep1"
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  assumes q2: "Quotient3 R2 Abs2 Rep2"
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  shows "(Rep2 ---> map_sum Abs1 Abs2) Inr = Inr"
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  apply(simp add: fun_eq_iff)
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  apply(simp add: Quotient3_abs_rep[OF q2])
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  done
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end