proposition: Lemma invR_gt0 x : x > 0 -> x^-1 > 0.
proof: Proof. by move=> x_gt0 /(leMl x_gt0); rewrite (divRR (gtR_neq x_gt0)) mulR0 => /ltR01. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)