proposition: Lemma mdeg_eq0I m : mdeg m = 0%N -> m = 1%M.
proof: Proof. move=> h; apply/eqP/cmP=> i; move: h; rewrite mdegE cm1. by case: mdomP=> // ki /eqP; rewrite (big_fsetD1 i) //= addn_eq0 => /andP[/eqP]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap