YES(?,ELEMENTARY)

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

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