proposition: Lemma oppR0 : - (0 : R) == 0.
proof: Proof. by apply: (@addRI 0); rewrite subRR add0R. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div order) mathcomp(ssralg ssrnum ssrint rat intdiv) Coq(Morphisms Setoid) fourcolor(real realsyntax)