free c:channel.

event A.
event B.

free a:bitstring[private].
free b:bitstring[private].

free d:bitstring.
free e:bitstring.

process
  in(c,(i:nat,x:bitstring));
  in(c,(j:nat,y:bitstring));
  if is_nat(i) then
  if is_nat(j) then
  if (i - 5) > j
  then out(c,choice[a,b])
  else out(c,choice[e,d])

(* EXPECTPV
RESULT Observational equivalence cannot be proved.
RESULT Observational equivalence cannot be proved.
0.080s (user 0.064s + system 0.016s), max rss 9352K
END *)
