(VAR x y )
(RULES 
        f(x, y) -> g1(x, x, y)
        f(x, y) -> g1(y, x, x)
        f(x, y) -> g2(x, y, y)
        f(x, y) -> g2(y, y, x)
        g1(x, x, y) -> h(x, y)
        g1(y, x, x) -> h(x, y)
        g2(x, y, y) -> h(x, y)
        g2(y, y, x) -> h(x, y)
        h(x, x) -> x
        
)