proposition: Lemma deg_Knm_r n m (y : 'I_m) : #|N(inr y : 'K_n,m)| = n.
proof: Proof. by rewrite opn_Knm_r card_imset ?cardsT ?card_ord //; exact: inl_inj. Qed.
imports: Coq(Setoid CMorphisms) mathcomp(all_ssreflect) GraphTheory(edone preliminaries bij digraph) GraphTheory(set_tac)