proposition: Lemma intrD m n : (m + n)%:~R = m%:~R + n%:~R :> R.
proof: Proof. exact: mulrzDr_tmp. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)