YES(?,ELEMENTARY)

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

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