(SIG
   (a   -> o)
   (c   -> o)
   (f   o -> o)
   (h   o o -> o)
   (b   -> o)
)
(RULES
   a -> c
   f(f(c)) -> h(a,h(h(c,c),b))
   f(f(a)) -> b
   b -> f(f(b))
)