YES(?,O(n^2)) TRS: { f mark X -> mark f X, f ok X -> ok f X, g ok X -> ok g X, h mark X -> mark h X, h ok X -> ok h X, active f X -> f active X, active f X -> mark g h f X, active h X -> h active X, proper f X -> f proper X, proper g X -> g proper X, proper h X -> h proper X, top mark X -> top proper X, top ok X -> top active X } DUP: We consider a non-duplicating system. Trs: { f mark X -> mark f X, f ok X -> ok f X, g ok X -> ok g X, h mark X -> mark h X, h ok X -> ok h X, active f X -> f active X, active f X -> mark g h f X, active h X -> h active X, proper f X -> f proper X, proper g X -> g proper X, proper h X -> h proper X, top mark X -> top proper X, top ok X -> top active X } Matrix Interpretation: Interpretation class: triangular [X1] [1 5][X1] [0] [top]([X0]) = [0 0][X0] + [0] [X1] [1 6][X1] [0] [ok]([X0]) = [0 1][X0] + [7] [X1] [1 1][X1] [0] [proper]([X0]) = [0 1][X0] + [0] [X1] [1 6][X1] [4] [active]([X0]) = [0 1][X0] + [5] [X1] [1 1][X1] [4] [mark]([X0]) = [0 1][X0] + [2] [X1] [1 2][X1] [0] [h]([X0]) = [0 1][X0] + [2] [X1] [1 1][X1] [0] [g]([X0]) = [0 1][X0] + [1] [X1] [1 4][X1] [7] [f]([X0]) = [0 1][X0] + [4] Qed