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 x = e
  then
    (if is_nat(j) then
    if is_nat(i) then
    if i > j -5
    then out(c,choice[a,b])
    else out(c,choice[e,d])
    )
  else
  (if is_nat(i) then
  if is_nat(j) then
  if j > i - 3
  then out(c,choice[e,a])
  else out(c,choice[b,d])
  )

(* EXPECTPV
RESULT Observational equivalence cannot be proved.
RESULT Observational equivalence cannot be proved.
0.216s (user 0.164s + system 0.052s), max rss 9428K
END *)
