fact: Definition nds_type X n k := (opos_below X n) /\ (exists m, [/\ ordinalp m, (forall i, i<c n -> m <=o odegree (X i)) & cardinal (Zo n (fun i => odegree (X i) = m)) = k]).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)