(VAR x y z v)
(RULES
h(x,x) -> h(a,b)
g(g(x,a),y) -> g(g(a,y),g(a,x))
f(g(x,y)) -> g(g(f(f(y)),h(a,a)),x)
h(h(f(f(x)),y),h(z,v)) -> h(h(f(z),f(f(f(y)))),h(v,x))
)