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