YES
O(n)
TRS:
 {
         .(x, 1()) -> x,
        .(x, i(x)) -> 1(),
  .(y, .(i(y), z)) -> z,
         .(1(), x) -> x,
        .(i(x), x) -> 1(),
  .(i(y), .(y, z)) -> z,
            i(1()) -> 1(),
           i(i(x)) -> x
 }
 Natural interpretation:
  Strict:
   {
           .(x, 1()) -> x,
          .(x, i(x)) -> 1(),
    .(y, .(i(y), z)) -> z,
           .(1(), x) -> x,
          .(i(x), x) -> 1(),
    .(i(y), .(y, z)) -> z,
              i(1()) -> 1(),
             i(i(x)) -> x
   }
  Weak:
   {}
  Interpretation class: stronglylinear
  [i](X0) = + 1*X0 + 1
  [1] = + 0
  [.](X1, X0) = + 1*X0 + 1*X1 + 1
  
  Qed