YES(?,O(n^1)) Problem: f(j(x,y),y) -> g(f(x,k(y))) f(x,h1(y,z)) -> h2(0(),x,h1(y,z)) g(h2(x,y,h1(z,u))) -> h2(s(x),y,h1(z,u)) h2(x,j(y,h1(z,u)),h1(z,u)) -> h2(s(x),y,h1(s(z),u)) i(f(x,h(y))) -> y i(h2(s(x),y,h1(x,z))) -> z k(h(x)) -> h1(0(),x) k(h1(x,y)) -> h1(s(x),y) Proof: Matrix Interpretation Processor: dimension: 1 interpretation: [i](x0) = x0 + 2, [h](x0) = x0 + 4, [s](x0) = x0, [h2](x0, x1, x2) = x0 + x1 + x2 + 9, [0] = 2, [h1](x0, x1) = x0 + x1, [g](x0) = x0 + 8, [k](x0) = x0 + 3, [f](x0, x1) = x0 + x1 + 16, [j](x0, x1) = x0 + x1 + 24 orientation: f(j(x,y),y) = x + 2y + 40 >= x + y + 27 = g(f(x,k(y))) f(x,h1(y,z)) = x + y + z + 16 >= x + y + z + 11 = h2(0(),x,h1(y,z)) g(h2(x,y,h1(z,u))) = u + x + y + z + 17 >= u + x + y + z + 9 = h2(s(x),y,h1(z,u)) h2(x,j(y,h1(z,u)),h1(z,u)) = 2u + x + y + 2z + 33 >= u + x + y + z + 9 = h2(s(x),y,h1(s(z),u)) i(f(x,h(y))) = x + y + 22 >= y = y i(h2(s(x),y,h1(x,z))) = 2x + y + z + 11 >= z = z k(h(x)) = x + 7 >= x + 2 = h1(0(),x) k(h1(x,y)) = x + y + 3 >= x + y = h1(s(x),y) problem: Qed