(* Title: HOL/Cardinals/Order_Union.thy
Author: Andrei Popescu, TU Muenchen
The ordinal-like sum of two orders with disjoint fields
*)
section \<open>Order Union\<close>
theory Order_Union
imports Main
begin
definition Osum :: "'a rel \<Rightarrow> 'a rel \<Rightarrow> 'a rel" (infix "Osum" 60) where
"r Osum r' = r \<union> r' \<union> {(a, a'). a \<in> Field r \<and> a' \<in> Field r'}"
notation Osum (infix "\<union>o" 60)
lemma Field_Osum: "Field (r \<union>o r') = Field r \<union> Field r'"
unfolding Osum_def Field_def by blast
lemma Osum_wf:
assumes FLD: "Field r Int Field r' = {}" and
WF: "wf r" and WF': "wf r'"
shows "wf (r Osum r')"
unfolding wf_eq_minimal2 unfolding Field_Osum
proof(intro allI impI, elim conjE)
fix A assume *: "A \<subseteq> Field r \<union> Field r'" and **: "A \<noteq> {}"
obtain B where B_def: "B = A Int Field r" by blast
show "\<exists>a\<in>A. \<forall>a'\<in>A. (a', a) \<notin> r \<union>o r'"
proof(cases "B = {}")
assume Case1: "B \<noteq> {}"
hence "B \<noteq> {} \<and> B \<le> Field r" using B_def by auto
then obtain a where 1: "a \<in> B" and 2: "\<forall>a1 \<in> B. (a1,a) \<notin> r"
using WF unfolding wf_eq_minimal2 by blast
hence 3: "a \<in> Field r \<and> a \<notin> Field r'" using B_def FLD by auto
(* *)
have "\<forall>a1 \<in> A. (a1,a) \<notin> r Osum r'"
proof(intro ballI)
fix a1 assume **: "a1 \<in> A"
{assume Case11: "a1 \<in> Field r"
hence "(a1,a) \<notin> r" using B_def ** 2 by auto
moreover
have "(a1,a) \<notin> r'" using 3 by (auto simp add: Field_def)
ultimately have "(a1,a) \<notin> r Osum r'"
using 3 unfolding Osum_def by auto
}
moreover
{assume Case12: "a1 \<notin> Field r"
hence "(a1,a) \<notin> r" unfolding Field_def by auto
moreover
have "(a1,a) \<notin> r'" using 3 unfolding Field_def by auto
ultimately have "(a1,a) \<notin> r Osum r'"
using 3 unfolding Osum_def by auto
}
ultimately show "(a1,a) \<notin> r Osum r'" by blast
qed
thus ?thesis using 1 B_def by auto
next
assume Case2: "B = {}"
hence 1: "A \<noteq> {} \<and> A \<le> Field r'" using * ** B_def by auto
then obtain a' where 2: "a' \<in> A" and 3: "\<forall>a1' \<in> A. (a1',a') \<notin> r'"
using WF' unfolding wf_eq_minimal2 by blast
hence 4: "a' \<in> Field r' \<and> a' \<notin> Field r" using 1 FLD by blast
(* *)
have "\<forall>a1' \<in> A. (a1',a') \<notin> r Osum r'"
proof(unfold Osum_def, auto simp add: 3)
fix a1' assume "(a1', a') \<in> r"
thus False using 4 unfolding Field_def by blast
next
fix a1' assume "a1' \<in> A" and "a1' \<in> Field r"
thus False using Case2 B_def by auto
qed
thus ?thesis using 2 by blast
qed
qed
lemma Osum_Refl:
assumes FLD: "Field r Int Field r' = {}" and
REFL: "Refl r" and REFL': "Refl r'"
shows "Refl (r Osum r')"
using assms
unfolding refl_on_def Field_Osum unfolding Osum_def by blast
lemma Osum_trans:
assumes FLD: "Field r Int Field r' = {}" and
TRANS: "trans r" and TRANS': "trans r'"
shows "trans (r Osum r')"
using assms unfolding Osum_def trans_def disjoint_iff Field_iff by blast
lemma Osum_Preorder:
"\<lbrakk>Field r Int Field r' = {}; Preorder r; Preorder r'\<rbrakk> \<Longrightarrow> Preorder (r Osum r')"
unfolding preorder_on_def using Osum_Refl Osum_trans by blast
lemma Osum_antisym:
assumes FLD: "Field r Int Field r' = {}" and
AN: "antisym r" and AN': "antisym r'"
shows "antisym (r Osum r')"
using assms by (auto simp: disjoint_iff antisym_def Osum_def Field_def)
lemma Osum_Partial_order:
"\<lbrakk>Field r Int Field r' = {}; Partial_order r; Partial_order r'\<rbrakk> \<Longrightarrow>
Partial_order (r Osum r')"
unfolding partial_order_on_def using Osum_Preorder Osum_antisym by blast
lemma Osum_Total:
assumes FLD: "Field r Int Field r' = {}" and
TOT: "Total r" and TOT': "Total r'"
shows "Total (r Osum r')"
using assms
unfolding total_on_def Field_Osum unfolding Osum_def by blast
lemma Osum_Linear_order:
"\<lbrakk>Field r Int Field r' = {}; Linear_order r; Linear_order r'\<rbrakk> \<Longrightarrow> Linear_order (r Osum r')"
by (simp add: Osum_Partial_order Osum_Total linear_order_on_def)
lemma Osum_minus_Id1:
assumes "r \<le> Id"
shows "(r Osum r') - Id \<le> (r' - Id) \<union> (Field r \<times> Field r')"
using assms by (force simp: Osum_def)
lemma Osum_minus_Id2:
assumes "r' \<le> Id"
shows "(r Osum r') - Id \<le> (r - Id) \<union> (Field r \<times> Field r')"
using assms by (force simp: Osum_def)
lemma Osum_minus_Id:
assumes TOT: "Total r" and TOT': "Total r'" and
NID: "\<not> (r \<le> Id)" and NID': "\<not> (r' \<le> Id)"
shows "(r Osum r') - Id \<le> (r - Id) Osum (r' - Id)"
using assms Total_Id_Field by (force simp: Osum_def)
lemma wf_Int_Times:
assumes "A Int B = {}"
shows "wf(A \<times> B)"
unfolding wf_def using assms by blast
lemma Osum_wf_Id:
assumes TOT: "Total r" and TOT': "Total r'" and
FLD: "Field r Int Field r' = {}" and
WF: "wf(r - Id)" and WF': "wf(r' - Id)"
shows "wf ((r Osum r') - Id)"
proof(cases "r \<le> Id \<or> r' \<le> Id")
assume Case1: "\<not>(r \<le> Id \<or> r' \<le> Id)"
have "Field(r - Id) Int Field(r' - Id) = {}"
using Case1 FLD TOT TOT' Total_Id_Field by blast
thus ?thesis
by (meson Case1 Osum_minus_Id Osum_wf TOT TOT' WF WF' wf_subset)
next
have 1: "wf(Field r \<times> Field r')"
using FLD by (auto simp add: wf_Int_Times)
assume Case2: "r \<le> Id \<or> r' \<le> Id"
moreover
{assume Case21: "r \<le> Id"
hence "(r Osum r') - Id \<le> (r' - Id) \<union> (Field r \<times> Field r')"
using Osum_minus_Id1[of r r'] by simp
moreover
{have "Domain(Field r \<times> Field r') Int Range(r' - Id) = {}"
using FLD unfolding Field_def by blast
hence "wf((r' - Id) \<union> (Field r \<times> Field r'))"
using 1 WF' wf_Un[of "Field r \<times> Field r'" "r' - Id"]
by (auto simp add: Un_commute)
}
ultimately have ?thesis using wf_subset by blast
}
moreover
{assume Case22: "r' \<le> Id"
hence "(r Osum r') - Id \<le> (r - Id) \<union> (Field r \<times> Field r')"
using Osum_minus_Id2[of r' r] by simp
moreover
{have "Range(Field r \<times> Field r') Int Domain(r - Id) = {}"
using FLD unfolding Field_def by blast
hence "wf((r - Id) \<union> (Field r \<times> Field r'))"
using 1 WF wf_Un[of "r - Id" "Field r \<times> Field r'"]
by (auto simp add: Un_commute)
}
ultimately have ?thesis using wf_subset by blast
}
ultimately show ?thesis by blast
qed
lemma Osum_Well_order:
assumes FLD: "Field r Int Field r' = {}" and
WELL: "Well_order r" and WELL': "Well_order r'"
shows "Well_order (r Osum r')"
proof-
have "Total r \<and> Total r'" using WELL WELL'
by (auto simp add: order_on_defs)
thus ?thesis using assms unfolding well_order_on_def
using Osum_Linear_order Osum_wf_Id by blast
qed
end