proposition: Lemma ltz1D x y : (x < 1 + y) = (x <= y).
proof: Proof. by rewrite -lez1D lerD2l. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)