YES(?,ELEMENTARY)

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           YES(?,ELEMENTARY)
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  +(0(), y) -> y
     , +(s(x), y) -> s(+(x, y))
     , +(s(x), y) -> +(x, s(y))}

Proof Output:    
  Strict Rules in Predicative Notation:
   {  +(0(); y) -> y
    , +(s(; x); y) -> s(; +(x; y))
    , +(s(; x); y) -> +(x; s(; y))}
  Safe Mapping:
   safe(+) = {2}, safe(0) = {}, safe(s) = {1}
  Argument Permutation:
   mu(+) = [1, 2]
  Precedence:
   + ~ +