free c:channel.

event A(nat).


query x:nat, x':nat;
  event(A(x)) ==> attacker(x') && x' <> x.

query x:nat, x':nat;
  event(A(x)) ==> attacker(x').

process
  event A(3)

(* EXPECTPV
RESULT event(A(x)) ==> attacker(x') && x' ≠ x cannot be proved.
RESULT event(A(x)) ==> attacker(x') is true.
0.012s (user 0.008s + system 0.004s), max rss 7716K
END *)
