Definition usual [local-0] A partial order is a preorder such that anti-symmetric, which means if A≤BA \le BA≤B and B≤AB \le AB≤A, then A=BA = BA=B. Definition as category [local-1] A category version is a preorder such that each isomorphism is identical (equality).
A partial order is a preorder such that anti-symmetric, which means if A≤BA \le BA≤B and B≤AB \le AB≤A, then A=BA = BA=B.