MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  U11(tt(), M, N) -> U12(tt(), M, N)
     , U12(tt(), M, N) -> s(plus(N, M))
     , U21(tt(), M, N) -> U22(tt(), M, N)
     , U22(tt(), M, N) -> plus(x(N, M), N)
     , plus(N, 0()) -> N
     , plus(N, s(M)) -> U11(tt(), M, N)
     , x(N, 0()) -> 0()
     , x(N, s(M)) -> U21(tt(), M, N)}

Proof Output:    
  The input cannot be shown compatible