YES O(n^2) 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 } DUP: We consider a non-duplicating system. 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 } Matrix Interpretation: Interpretation class: triangular [X1] [1 1][X1] [0] [i]([X0]) = [0 1][X0] + [1] [0] [1] = [1] [X3] [X1] [1 0][X3] [1 0][X1] [1] [.]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [0] Qed