(VAR x y z )
(RULES 
        cond1(true, x, y, z) -> cond2(gr(y, z), x, y, z)
        cond2(true, x, y, z) -> cond2(gr(y, z), x, p(y), z)
        cond2(false, x, y, z) -> cond1(gr(x, z), p(x), y, z)
        gr(0, x) -> false
        gr(s(x), 0) -> true
        gr(s(x), s(y)) -> gr(x, y)
        p(0) -> 0
        p(s(x)) -> x
        
)