proposition: Lemma ltPR x : x - 1 < x.
proof: Proof. by rewrite -subR_le0 oppRB addRCA subRR addR0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)