YES Problem: f(f(x)) -> f(g(f(x),x)) f(f(x)) -> f(h(f(x),f(x))) g(x,y) -> y h(x,x) -> g(x,0()) Proof: DP Processor: DPs: f#(f(x)) -> g#(f(x),x) f#(f(x)) -> f#(g(f(x),x)) f#(f(x)) -> h#(f(x),f(x)) f#(f(x)) -> f#(h(f(x),f(x))) h#(x,x) -> g#(x,0()) TRS: f(f(x)) -> f(g(f(x),x)) f(f(x)) -> f(h(f(x),f(x))) g(x,y) -> y h(x,x) -> g(x,0()) Arctic Interpretation Processor: dimension: 1 usable rules: f(f(x)) -> f(g(f(x),x)) f(f(x)) -> f(h(f(x),f(x))) g(x,y) -> y h(x,x) -> g(x,0()) interpretation: [h#](x0, x1) = x0 + x1 + 2, [g#](x0, x1) = x1 + 0, [f#](x0) = 1x0 + 0, [0] = 0, [h](x0, x1) = 2, [g](x0, x1) = 1x1 + 1, [f](x0) = 2x0 + 4 orientation: f#(f(x)) = 3x + 5 >= x + 0 = g#(f(x),x) f#(f(x)) = 3x + 5 >= 2x + 2 = f#(g(f(x),x)) f#(f(x)) = 3x + 5 >= 2x + 4 = h#(f(x),f(x)) f#(f(x)) = 3x + 5 >= 3 = f#(h(f(x),f(x))) h#(x,x) = x + 2 >= 0 = g#(x,0()) f(f(x)) = 4x + 6 >= 3x + 4 = f(g(f(x),x)) f(f(x)) = 4x + 6 >= 4 = f(h(f(x),f(x))) g(x,y) = 1y + 1 >= y = y h(x,x) = 2 >= 1 = g(x,0()) problem: DPs: TRS: f(f(x)) -> f(g(f(x),x)) f(f(x)) -> f(h(f(x),f(x))) g(x,y) -> y h(x,x) -> g(x,0()) Qed