(* Equivalence is true because the computation of r(a,b) always fails *)

free c, a, b. 786787777777777777777777777777777777777777777777777

reduc r(x,x) = x.

process
        let x = r(a,b) in let y = choice[x,a] in out(c,y)

(* EXPECTPV
Error: Incorrect integer.
xtime: error in child process (status : 2)
END *)
