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

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