free c:channel.

event A.
event B.

fun couple(nat,nat):bitstring.
fun proj(bitstring,nat):nat
reduc forall i:nat,j:nat; proj(couple(i,j),1) = i
otherwise forall i:nat,j:nat; proj(couple(i,j),2) = i.

query event(A); event(B).

process
  in(c,i:nat);
  let j:nat suchthat proj(couple(i,i),1) <= j in
    event A
  else
    event B

(* EXPECTPV
Error: <= should be a predicate.
xtime: error in child process (status : 2)
END *)
