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