YES Problem: f(f(x,y,z),u,f(x,y,v)) -> f(x,y,f(z,u,v)) f(x,y,y) -> y f(x,y,g(y)) -> x f(x,x,y) -> x f(g(x),x,y) -> y Proof: Matrix Interpretation Processor: dim=1 interpretation: [g](x0) = 4x0 + 4, [f](x0, x1, x2) = 2x0 + 2x1 + x2 orientation: f(f(x,y,z),u,f(x,y,v)) = 2u + v + 6x + 6y + 2z >= 2u + v + 2x + 2y + 2z = f(x,y,f(z,u,v)) f(x,y,y) = 2x + 3y >= y = y f(x,y,g(y)) = 2x + 6y + 4 >= x = x f(x,x,y) = 4x + y >= x = x f(g(x),x,y) = 10x + y + 8 >= y = y problem: f(f(x,y,z),u,f(x,y,v)) -> f(x,y,f(z,u,v)) f(x,y,y) -> y f(x,x,y) -> x Matrix Interpretation Processor: dim=1 interpretation: [f](x0, x1, x2) = x0 + 2x1 + x2 + 7 orientation: f(f(x,y,z),u,f(x,y,v)) = 2u + v + 2x + 4y + z + 21 >= 2u + v + x + 2y + z + 14 = f(x,y,f(z,u,v)) f(x,y,y) = x + 3y + 7 >= y = y f(x,x,y) = 3x + y + 7 >= x = x problem: Qed