MAYBE
MAYBE
TRS:
 {
          dbl(0()) -> 0(),
          dbl(s()) -> s(),
       dbls(nil()) -> nil(),
      dbls(cons()) -> cons(),
  sel(0(), cons()) -> X,
  sel(s(), cons()) -> sel(X, Z),
       indx(nil()) -> nil(),
      indx(cons()) -> cons(),
            from() -> cons()
 }
 DUP: We consider a duplicating system.
  Trs:
   {
            dbl(0()) -> 0(),
            dbl(s()) -> s(),
         dbls(nil()) -> nil(),
        dbls(cons()) -> cons(),
    sel(0(), cons()) -> X,
    sel(s(), cons()) -> sel(X, Z),
         indx(nil()) -> nil(),
        indx(cons()) -> cons(),
              from() -> cons()
   }
  Fail