(VAR x y z v u)
(RULES
f(true, x, y, z) -> g(gt(x, y), x, y, z)
g(true, x, y, z) -> f(gt(x, z), x, s(y), z)
g(true, x, y, z) -> f(gt(x, z), x, y, s(z))
gt(0, v) -> false
gt(s(u), 0) -> true
gt(s(u), s(v)) -> gt(u, v)
)