(VAR x y )
(RULES 
        cond1(true, x, y) -> cond2(gr(x, y), x, y)
        cond2(true, x, y) -> cond1(gr0(x), y, y)
        cond2(false, x, y) -> cond1(gr0(x), p(x), y)
        gr(0, x) -> false
        gr(s(x), 0) -> true
        gr(s(x), s(y)) -> gr(x, y)
        gr0(0) -> false
        gr0(s(x)) -> true
        p(0) -> 0
        p(s(x)) -> x
        
)