proposition: Lemma supdomeqUh h1 h2 h : def (h2 :+ h) -> (def h2 -> supdom h2 h1) -> supdom (h2 :+ h) (h1 :+ h).
proof: Proof. by rewrite (unC h1); apply: sexit1. Qed.
imports: mathcomp(ssreflect ssrfun ssrnat div ssrbool seq) LemmaOverloading(prelude finmap ordtype) mathcomp(path eqtype) Eqdep