MAYBE
* Step 1: Failure MAYBE
  + Considered Problem:
      - Strict TRS:
          ack(Cons(x,xs),Nil()) -> ack(xs,Cons(Nil(),Nil()))
          ack(Cons(x',xs'),Cons(x,xs)) -> ack(xs',ack(Cons(x',xs'),xs))
          ack(Nil(),n) -> Cons(Cons(Nil(),Nil()),n)
          goal(m,n) -> ack(m,n)
      - Signature:
          {ack/2,goal/2} / {Cons/2,Nil/0}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {ack,goal} and constructors {Cons,Nil}
  + Applied Processor:
      NaturalPI {shape = Mixed 3, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
  + Details:
      Incompatible
MAYBE