YES(?,ELEMENTARY)

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           YES(?,ELEMENTARY)
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  rev(xs) -> revtl(xs, nil())
     , revtl(nil(), ys) -> ys
     , revtl(cons(x, xs), ys) -> revtl(xs, cons(x, ys))}

Proof Output:    
  Strict Rules in Predicative Notation:
   {  rev(xs;) -> revtl(xs; nil())
    , revtl(nil(); ys) -> ys
    , revtl(cons(; x, xs); ys) -> revtl(xs; cons(; x, ys))}
  Safe Mapping:
   safe(rev) = {}, safe(revtl) = {2}, safe(nil) = {},
   safe(cons) = {1, 2}
  Argument Permutation:
   mu(rev) = [1], mu(revtl) = [1, 2]
  Precedence:
   revtl ~ revtl, rev > revtl, rev ~ rev