(VAR x y z )
(RULES 
        h(e(x), y) -> h(d(x, y), s(y))
        d(g(g(0, x), y), s(z)) -> g(e(x), d(g(g(0, x), y), z))
        d(g(g(0, x), y), 0) -> e(y)
        d(g(0, x), y) -> e(x)
        d(g(x, y), z) -> g(d(x, z), e(y))
        g(e(x), e(y)) -> e(g(x, y))
        
)