YES(?,O(n^2)) TRS: { __(X, nil()) -> X, __(nil(), X) -> X, __(__(X, Y), Z) -> __(X, __(Y, Z)), activate X -> X, and(tt(), X) -> activate X, isNePal __(I, __(P, I)) -> tt() } DUP: We consider a non-duplicating system. Trs: { __(X, nil()) -> X, __(nil(), X) -> X, __(__(X, Y), Z) -> __(X, __(Y, Z)), activate X -> X, and(tt(), X) -> activate X, isNePal __(I, __(P, I)) -> tt() } Matrix Interpretation: Interpretation class: triangular [X1] [1 1][X1] [0] [isNePal]([X0]) = [0 1][X0] + [1] [0] [tt] = [0] [X3] [X1] [1 0][X3] [1 0][X1] [2] [and]([X2], [X0]) = [0 0][X2] + [0 1][X0] + [0] [X1] [1 0][X1] [1] [activate]([X0]) = [0 1][X0] + [0] [X3] [X1] [1 2][X3] [1 0][X1] [0] [__]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [2] [1] [nil] = [0] Qed