(VAR x y )
(RULES 
        g(x, x) -> g(a, b)
        g(c, g(c, x)) -> g(e, g(d, x))
        g(d, g(d, x)) -> g(c, g(e, x))
        g(e, g(e, x)) -> g(d, g(c, x))
        f(g(x, y)) -> g(y, g(f(f(x)), a))
        
)