MAYBE

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  f(x, y) -> cond(and(isNat(x), isNat(y)), x, y)
     , cond(tt(), x, y) -> f(s(x), s(y))
     , isNat(s(x)) -> isNat(x)
     , isNat(0()) -> tt()
     , and(tt(), tt()) -> tt()
     , and(ff(), x) -> ff()
     , and(x, ff()) -> ff()}

Proof Output:    
  The input cannot be shown compatible