YES Problem: g(c(x,s(y))) -> g(c(s(x),y)) f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) f(x) -> x Proof: DP Processor: DPs: g#(c(x,s(y))) -> g#(c(s(x),y)) f#(c(s(x),y)) -> f#(c(x,s(y))) f#(f(x)) -> f#(d(f(x))) TRS: g(c(x,s(y))) -> g(c(s(x),y)) f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) f(x) -> x Usable Rule Processor: DPs: g#(c(x,s(y))) -> g#(c(s(x),y)) f#(c(s(x),y)) -> f#(c(x,s(y))) f#(f(x)) -> f#(d(f(x))) TRS: f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) f(x) -> x Matrix Interpretation Processor: dim=2 usable rules: interpretation: [f#](x0) = [1 0]x0, [g#](x0) = [0 2]x0, [0] [d](x0) = [3], [2] [f](x0) = [0], [0 2] [0 1] [3] [c](x0, x1) = [0 0]x0 + [1 1]x1 + [0], [1 1] [0] [s](x0) = [0 1]x0 + [1] orientation: g#(c(x,s(y))) = [2 4]y + [2] >= [2 2]y = g#(c(s(x),y)) f#(c(s(x),y)) = [0 2]x + [0 1]y + [5] >= [0 2]x + [0 1]y + [4] = f#(c(x,s(y))) f#(f(x)) = [2] >= [0] = f#(d(f(x))) [2] [2] f(c(s(x),y)) = [0] >= [0] = f(c(x,s(y))) [2] [2] f(f(x)) = [0] >= [0] = f(d(f(x))) [2] f(x) = [0] >= x = x problem: DPs: TRS: f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) f(x) -> x Qed