(* Compatibility *)
Notation sym_JMeq := JMeq_sym (only parsing).Notation trans_JMeq := JMeq_trans (only parsing).

Lemma JMeq_sumtype_ll: forall (A: Type) (B: Type) (C: Type) (D: Type) (x: A) (y: C), @eq Type A C -> @eq Type B D -> (@JMeq (A + B) (inl x) (C + D) (inl y)) -> JMeq x y.