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