MAYBE
MAYBE
TRS:
 {
                 :(x, x) -> e(),
               :(x, e()) -> x,
  :(x, :(y, :(i(x), z))) -> :(i(z), y),
        :(x, :(y, i(x))) -> i(y),
               :(e(), x) -> i(x),
           :(:(x, y), z) -> :(x, :(z, i(y))),
        :(i(x), :(y, x)) -> i(y),
  :(i(x), :(y, :(x, z))) -> :(i(z), y),
                  i(e()) -> e(),
              i(:(x, y)) -> :(y, x),
                 i(i(x)) -> x
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
                   :(x, x) -> e(),
                 :(x, e()) -> x,
    :(x, :(y, :(i(x), z))) -> :(i(z), y),
          :(x, :(y, i(x))) -> i(y),
                 :(e(), x) -> i(x),
             :(:(x, y), z) -> :(x, :(z, i(y))),
          :(i(x), :(y, x)) -> i(y),
    :(i(x), :(y, :(x, z))) -> :(i(z), y),
                    i(e()) -> e(),
                i(:(x, y)) -> :(y, x),
                   i(i(x)) -> x
   }
  Fail