MAYBE

'Pop* with parameter subtitution (timeout of 60.0 seconds)'
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Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  -(x, 0()) -> x
     , -(s(x), s(y)) -> -(x, y)
     , <=(0(), y) -> true()
     , <=(s(x), 0()) -> false()
     , <=(s(x), s(y)) -> <=(x, y)
     , if(true(), x, y) -> x
     , if(false(), x, y) -> y
     , perfectp(0()) -> false()
     , perfectp(s(x)) -> f(x, s(0()), s(x), s(x))
     , f(0(), y, 0(), u) -> true()
     , f(0(), y, s(z), u) -> false()
     , f(s(x), 0(), z, u) -> f(x, u, -(z, s(x)), u)
     , f(s(x), s(y), z, u) ->
       if(<=(x, y), f(s(x), -(y, x), z, u), f(x, u, z, u))}

Proof Output:    
  The input cannot be shown compatible