(* ID : $Id$
Author : Tobias Nipkow
*)
header {* Orders as Relations *}
theory Order_Relation
imports Plain "~~/src/HOL/Hilbert_Choice" "~~/src/HOL/ATP_Linkup"
begin
text{* This prelude could be moved to theory Relation: *}
definition "irrefl r \<equiv> \<forall>x. (x,x) \<notin> r"
definition "total_on A r \<equiv> \<forall>x\<in>A.\<forall>y\<in>A. x\<noteq>y \<longrightarrow> (x,y)\<in>r \<or> (y,x)\<in>r"
abbreviation "total \<equiv> total_on UNIV"
lemma total_on_empty[simp]: "total_on {} r"
by(simp add:total_on_def)
lemma refl_on_converse[simp]: "refl A (r^-1) = refl A r"
by(auto simp add:refl_def)
lemma total_on_converse[simp]: "total_on A (r^-1) = total_on A r"
by (auto simp: total_on_def)
lemma irrefl_diff_Id[simp]: "irrefl(r-Id)"
by(simp add:irrefl_def)
declare [[simp_depth_limit = 2]]
lemma trans_diff_Id: " trans r \<Longrightarrow> antisym r \<Longrightarrow> trans (r-Id)"
by(simp add: antisym_def trans_def) blast
declare [[simp_depth_limit = 50]]
lemma total_on_diff_Id[simp]: "total_on A (r-Id) = total_on A r"
by(simp add: total_on_def)
subsection{* Orders on a set *}
definition "preorder_on A r \<equiv> refl A r \<and> trans r"
definition "partial_order_on A r \<equiv> preorder_on A r \<and> antisym r"
definition "linear_order_on A r \<equiv> partial_order_on A r \<and> total_on A r"
definition "strict_linear_order_on A r \<equiv> trans r \<and> irrefl r \<and> total_on A r"
definition "well_order_on A r \<equiv> linear_order_on A r \<and> wf(r - Id)"
lemmas order_on_defs =
preorder_on_def partial_order_on_def linear_order_on_def
strict_linear_order_on_def well_order_on_def
lemma preorder_on_empty[simp]: "preorder_on {} {}"
by(simp add:preorder_on_def trans_def)
lemma partial_order_on_empty[simp]: "partial_order_on {} {}"
by(simp add:partial_order_on_def)
lemma lnear_order_on_empty[simp]: "linear_order_on {} {}"
by(simp add:linear_order_on_def)
lemma well_order_on_empty[simp]: "well_order_on {} {}"
by(simp add:well_order_on_def)
lemma preorder_on_converse[simp]: "preorder_on A (r^-1) = preorder_on A r"
by (simp add:preorder_on_def)
lemma partial_order_on_converse[simp]:
"partial_order_on A (r^-1) = partial_order_on A r"
by (simp add: partial_order_on_def)
lemma linear_order_on_converse[simp]:
"linear_order_on A (r^-1) = linear_order_on A r"
by (simp add: linear_order_on_def)
lemma strict_linear_order_on_diff_Id:
"linear_order_on A r \<Longrightarrow> strict_linear_order_on A (r-Id)"
by(simp add: order_on_defs trans_diff_Id)
subsection{* Orders on the field *}
abbreviation "Refl r \<equiv> refl (Field r) r"
abbreviation "Preorder r \<equiv> preorder_on (Field r) r"
abbreviation "Partial_order r \<equiv> partial_order_on (Field r) r"
abbreviation "Total r \<equiv> total_on (Field r) r"
abbreviation "Linear_order r \<equiv> linear_order_on (Field r) r"
abbreviation "Well_order r \<equiv> well_order_on (Field r) r"
lemma subset_Image_Image_iff:
"\<lbrakk> Preorder r; A \<subseteq> Field r; B \<subseteq> Field r\<rbrakk> \<Longrightarrow>
r `` A \<subseteq> r `` B \<longleftrightarrow> (\<forall>a\<in>A.\<exists>b\<in>B. (b,a):r)"
apply(auto simp add: subset_eq preorder_on_def refl_def Image_def)
apply metis
by(metis trans_def)
lemma subset_Image1_Image1_iff:
"\<lbrakk> Preorder r; a : Field r; b : Field r\<rbrakk> \<Longrightarrow> r `` {a} \<subseteq> r `` {b} \<longleftrightarrow> (b,a):r"
by(simp add:subset_Image_Image_iff)
lemma Refl_antisym_eq_Image1_Image1_iff:
"\<lbrakk>Refl r; antisym r; a:Field r; b:Field r\<rbrakk> \<Longrightarrow> r `` {a} = r `` {b} \<longleftrightarrow> a=b"
by(simp add: expand_set_eq antisym_def refl_def) metis
lemma Partial_order_eq_Image1_Image1_iff:
"\<lbrakk>Partial_order r; a:Field r; b:Field r\<rbrakk> \<Longrightarrow> r `` {a} = r `` {b} \<longleftrightarrow> a=b"
by(auto simp:order_on_defs Refl_antisym_eq_Image1_Image1_iff)
subsection{* Orders on a type *}
abbreviation "strict_linear_order \<equiv> strict_linear_order_on UNIV"
abbreviation "linear_order \<equiv> linear_order_on UNIV"
abbreviation "well_order r \<equiv> well_order_on UNIV"
end