YES(?,ELEMENTARY)

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           YES(?,ELEMENTARY)
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  zeros() -> cons(0(), n__zeros())
     , tail(cons(X, XS)) -> activate(XS)
     , zeros() -> n__zeros()
     , activate(n__zeros()) -> zeros()
     , activate(X) -> X}

Proof Output:    
  Strict Rules in Predicative Notation:
   {  zeros() -> cons(; 0(), n__zeros())
    , tail(cons(; X, XS);) -> activate(; XS)
    , zeros() -> n__zeros()
    , activate(; n__zeros()) -> zeros()
    , activate(; X) -> X}
  Safe Mapping:
   safe(zeros) = {}, safe(cons) = {1, 2}, safe(0) = {},
   safe(n__zeros) = {}, safe(tail) = {}, safe(activate) = {1}
  Argument Permutation:
   mu(zeros) = [], mu(tail) = [1], mu(activate) = [1]
  Precedence:
   activate ~ activate, activate > zeros, tail > activate,
   tail ~ tail, tail > zeros, zeros ~ zeros