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