(* Compatibility *)
Notation sym_JMeq := JMeq_sym (only parsing).
Notation trans_JMeq := JMeq_trans (only parsing).
(******************************************  The following is the original floyd/jmeq_lemmas.v  ******************************************)

Lemma JMeq_fst: forall (A: Type) (B: Type) (C: Type) (D: Type) (x: A*B) (y: C*D), @eq Type A C -> @eq Type B D -> JMeq x y -> JMeq (fst x) (fst y).