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