MAYBE
* Step 1: Failure MAYBE
  + Considered Problem:
      - Strict TRS:
          a__b() -> a()
          a__b() -> b()
          a__f(X,X) -> a__f(a(),b())
          a__f(X1,X2) -> f(X1,X2)
          mark(a()) -> a()
          mark(b()) -> a__b()
          mark(f(X1,X2)) -> a__f(mark(X1),X2)
      - Signature:
          {a__b/0,a__f/2,mark/1} / {a/0,b/0,f/2}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {a__b,a__f,mark} and constructors {a,b,f}
  + Applied Processor:
      NaturalPI {shape = Mixed 3, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
  + Details:
      Incompatible
MAYBE