proposition: Lemma leq_trunc_divp d m : size (m %/ d * d) <= size m.
proof: Proof. have [-> | dn0] := eqVneq d 0; first by rewrite mulr0 size_poly0. by apply: IdomainUnit.leq_trunc_divp; rewrite unitfE lead_coef_eq0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop ssralg poly)