proposition: Lemma ordinal_o_isu2 r x: worder r -> ordinalp x -> r \Is (ordinal_o x) -> ordinal r = x.
proof: Proof. move=> wo ox oi. by rewrite (ordinal_o_isu1 wo (ordinal_o_wor ox) oi) (ordinal_o_o ox). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)