Lemma split_4eq: forall (T : Type) (c0 c1 c2 c3 c0' c1' c2' c3' : T),
(c0, c1, c2, c3) = (c0', c1', c2', c3') ->
c0 = c0' /\ c1 = c1' /\ c2 = c2' /\ c3 = c3'.