header {* Order on product types *}
theory Product_ord
imports Main
begin
instantiation "*" :: (ord, ord) ord
begin
definition
prod_le_def [code del]: "x ≤ y <-> fst x < fst y ∨ fst x = fst y ∧ snd x ≤ snd y"
definition
prod_less_def [code del]: "x < y <-> fst x < fst y ∨ fst x = fst y ∧ snd x < snd y"
instance ..
end
lemma [code]:
"(x1::'a::{ord, eq}, y1) ≤ (x2, y2) <-> x1 < x2 ∨ x1 = x2 ∧ y1 ≤ y2"
"(x1::'a::{ord, eq}, y1) < (x2, y2) <-> x1 < x2 ∨ x1 = x2 ∧ y1 < y2"
unfolding prod_le_def prod_less_def by simp_all
instance * :: (order, order) order
by default (auto simp: prod_le_def prod_less_def intro: order_less_trans)
instance * :: (linorder, linorder) linorder
by default (auto simp: prod_le_def)
instantiation * :: (linorder, linorder) distrib_lattice
begin
definition
inf_prod_def: "(inf :: 'a × 'b => _ => _) = min"
definition
sup_prod_def: "(sup :: 'a × 'b => _ => _) = max"
instance
by intro_classes
(auto simp add: inf_prod_def sup_prod_def min_max.sup_inf_distrib1)
end
end