YES(?,ELEMENTARY)

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

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