fact: Definition subdom h1 h2 := if (h1, h2) is (Def hs1 _, Def hs2 _) then all (fun x => x \in supp hs2) (supp hs1) else false.
imports: mathcomp(ssreflect ssrfun ssrnat div ssrbool seq) LemmaOverloading(prelude finmap ordtype) mathcomp(path eqtype) Eqdep