proposition: Lemma mulIR x y z : x != 0 -> y * x == z * x -> y == z.
proof: Proof. by rewrite -!(mulRC x); apply: mulRI. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)