(VAR x y )
(RULES 
        cond1(true, x, y) -> cond2(gr(x, 0), x, y)
        cond2(true, x, y) -> cond1(or(gr(x, 0), gr(y, 0)), p(x), y)
        cond2(false, x, y) -> cond3(gr(y, 0), x, y)
        cond3(true, x, y) -> cond1(or(gr(x, 0), gr(y, 0)), x, p(y))
        cond3(false, x, y) -> cond1(or(gr(x, 0), gr(y, 0)), x, y)
        gr(0, x) -> false
        gr(s(x), 0) -> true
        gr(s(x), s(y)) -> gr(x, y)
        or(false, false) -> false
        or(true, x) -> true
        or(x, true) -> true
        p(0) -> 0
        p(s(x)) -> x
        
)