Date: Sep 18, 2013 12:20 AM
Author: William Elliot
Subject: Homomorphism of posets and lattices
What's your opinion about the following except from a manuscript?

I consider the Definition 2.92 to be in error unless the domain

of the function is a linear order. For example, the identity

function from a two point antichain { a,b } to the chain a < b.

Comments? Are not antichains preserved by order isomorphisms?

2,1,12 Homomorphism of posets and lattices

Definition 2.90. A monotone function (also called order homomorphism) from

a poset A to a poset B is such a function f that x <= y --> f(x) <= f(y).

Definition 2.91. Order embedding is an injective monotone function.

Definition 2.92. Order isomorphism is an surjective order embadding

(= bijective monotone function).

Order isomorphism preserves properties of posets, such as

order, joins and meets, etc.

Definition 2.93.