YES(?,O(n^2)) TRS: { f(a x, a y) -> a f(x, y), f(b x, b y) -> b f(x, y), a a f(x, y) -> f(a b a b a x, a b a b a y) } DUP: We consider a non-duplicating system. Trs: { f(a x, a y) -> a f(x, y), f(b x, b y) -> b f(x, y), a a f(x, y) -> f(a b a b a x, a b a b a y) } Matrix Interpretation: Interpretation class: triangular [X1] [1 0][X1] [1] [b]([X0]) = [0 0][X0] + [0] [X1] [1 3][X1] [1] [a]([X0]) = [0 1][X0] + [3] [X3] [X1] [1 0][X3] [1 0][X1] [2] [f]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [0] Qed