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