free c:channel.
free a:bitstring.
free b:bitstring.

event A(bitstring).
event B(bitstring).
event C.

lemma i:time, j:time, x:bitstring; event(A(x))@i && inj-event(B(x)) ==> inj-event(C)@j || j < i.

process
  event C;
  event A(a);
  event A(b);
  event B(a);
  event B(b)

(* EXPECTPV
Error: Declared lemmas, axioms, and restrictions should not contain injective events in their premise.
xtime: error in child process (status : 2)
END *)
