MAYBE
MAYBE
TRS:
 {
                     from(X) -> cons(X, n__from(n__s(X))),
                     from(X) -> n__from(X),
               first(X1, X2) -> n__first(X1, X2),
               first(0(), Z) -> nil(),
     first(s(X), cons(Y, Z)) -> cons(Y, n__first(X, activate(Z))),
                 activate(X) -> X,
        activate(n__from(X)) -> from(activate(X)),
           activate(n__s(X)) -> s(activate(X)),
  activate(n__first(X1, X2)) -> first(activate(X1), activate(X2)),
                        s(X) -> n__s(X),
        sel(0(), cons(X, Z)) -> X,
       sel(s(X), cons(Y, Z)) -> sel(X, activate(Z))
 }
 DUP: We consider a duplicating system.
  Trs:
   {
                       from(X) -> cons(X, n__from(n__s(X))),
                       from(X) -> n__from(X),
                 first(X1, X2) -> n__first(X1, X2),
                 first(0(), Z) -> nil(),
       first(s(X), cons(Y, Z)) -> cons(Y, n__first(X, activate(Z))),
                   activate(X) -> X,
          activate(n__from(X)) -> from(activate(X)),
             activate(n__s(X)) -> s(activate(X)),
    activate(n__first(X1, X2)) -> first(activate(X1), activate(X2)),
                          s(X) -> n__s(X),
          sel(0(), cons(X, Z)) -> X,
         sel(s(X), cons(Y, Z)) -> sel(X, activate(Z))
   }
  Fail