YES(?,O(n^2)) TRS: { f mark X -> f X, f active X -> f X, g mark X -> g X, g active X -> g X, h mark X -> h X, h active X -> h X, mark f X -> active f mark X, mark g X -> active g X, mark h X -> active h mark X, mark c X -> active c X, mark d X -> active d X, c mark X -> c X, c active X -> c X, active f f X -> mark c f g f X, active h X -> mark c d X, active c X -> mark d X, d mark X -> d X, d active X -> d X } DUP: We consider a non-duplicating system. Trs: { f mark X -> f X, f active X -> f X, g mark X -> g X, g active X -> g X, h mark X -> h X, h active X -> h X, mark f X -> active f mark X, mark g X -> active g X, mark h X -> active h mark X, mark c X -> active c X, mark d X -> active d X, c mark X -> c X, c active X -> c X, active f f X -> mark c f g f X, active h X -> mark c d X, active c X -> mark d X, d mark X -> d X, d active X -> d X } Matrix Interpretation: Interpretation class: triangular [X1] [1 0][X1] [0] [d]([X0]) = [0 0][X0] + [0] [X1] [1 0][X1] [4] [active]([X0]) = [0 1][X0] + [0] [X1] [1 0][X1] [3] [c]([X0]) = [0 0][X0] + [0] [X1] [1 4][X1] [6] [mark]([X0]) = [0 1][X0] + [0] [X1] [1 0][X1] [6] [h]([X0]) = [0 1][X0] + [2] [X1] [1 0][X1] [0] [g]([X0]) = [0 0][X0] + [0] [X1] [1 7][X1] [2] [f]([X0]) = [0 1][X0] + [2] Qed