proposition: Lemma loweqK h1 h2 t1 t2 : def (h1 :+ t1) -> def (h2 :+ t2) -> h1 =~ h2 -> h1 :+ t1 =~ h2 :+ t2 -> t1 =~ t2.
proof: Proof. move=>D1 D2. case: loweqP=>// E1 _; case: loweqP=>// E2 _; apply/loweqP. by apply: ldomK E2. Qed.
imports: mathcomp(ssreflect ssrfun ssrnat div ssrbool seq) LemmaOverloading(prelude finmap ordtype) mathcomp(path eqtype) Eqdep