YES(?,ELEMENTARY)

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           YES(?,ELEMENTARY)
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  d(x) -> e(u(x))
     , d(u(x)) -> c(x)
     , c(u(x)) -> b(x)
     , v(e(x)) -> x
     , b(u(x)) -> a(e(x))}

Proof Output:    
  Strict Rules in Predicative Notation:
   {  d(x;) -> e(; u(; x))
    , d(u(; x);) -> c(x;)
    , c(u(; x);) -> b(; x)
    , v(; e(; x)) -> x
    , b(; u(; x)) -> a(; e(; x))}
  Safe Mapping:
   safe(d) = {}, safe(e) = {1}, safe(u) = {1}, safe(c) = {},
   safe(b) = {1}, safe(v) = {1}, safe(a) = {1}
  Argument Permutation:
   mu(d) = [1], mu(c) = [1], mu(b) = [1], mu(v) = [1]
  Precedence:
   v ~ v, v ~ b, b ~ v, b ~ b, c > v, c > b, c ~ c, c ~ d, d > v,
   d > b, d ~ c, d ~ d