Problem:
 b() -> h(b(),a())
 b() -> h(f(b()),f(h(b(),a())))

Proof:
 Uncurry Processor:
  b() -> f4(f4(h(),b()),a())
  b() -> f4(f4(h(),f4(f(),b())),f4(f(),f4(f4(h(),b()),a())))
  Ground Confluence Processor:
   non-confluent by decision procedure.