proposition: Fact lex1 (x : T * T') : x <= (\top, \top) :> T * T'.
proof: Proof. by case: x => // x1 x2; rewrite leEprodlexi/= !lex1 implybT. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)