proposition: Lemma clos_trans_imm2 : forall A (r : relation A) (I: irreflexive r) (T: transitive r) L a b (D: forall c, r a c -> r c b -> In c L) (REL: r a b), (immediate r)⁺ a b.
proof: Proof. ins; eapply clos_trans_imm with (L := undup L); ins; try rewrite in_undup_iff; eauto using nodup_undup. Qed.
imports: Program.Basics Arith micromega.Lia Permutation List Setoid HahnBase HahnList HahnRelationsBasic HahnSets