YES Problem: p(p(b(a(x0)),x1),p(x2,x3)) -> p(p(x3,a(x2)),p(b(a(x1)),b(x0))) Proof: DP Processor: DPs: p#(p(b(a(x0)),x1),p(x2,x3)) -> p#(b(a(x1)),b(x0)) p#(p(b(a(x0)),x1),p(x2,x3)) -> p#(x3,a(x2)) p#(p(b(a(x0)),x1),p(x2,x3)) -> p#(p(x3,a(x2)),p(b(a(x1)),b(x0))) TRS: p(p(b(a(x0)),x1),p(x2,x3)) -> p(p(x3,a(x2)),p(b(a(x1)),b(x0))) Matrix Interpretation Processor: dim=3 interpretation: [p#](x0, x1) = [1 0 0]x0 + [0 1 0]x1, [0 0 1] [0 0 0] [p](x0, x1) = [2 1 0]x0 + [1 2 1]x1 [0 0 0] [0 0 0] , [0 0 0] [b](x0) = [0 0 0]x0 [0 2 0] , [0 0 0] [0] [a](x0) = [0 1 0]x0 + [1] [0 0 0] [0] orientation: p#(p(b(a(x0)),x1),p(x2,x3)) = [0 2 0]x0 + [2 1 0]x2 + [1 2 1]x3 + [2] >= [0] = p#(b(a(x1)),b(x0)) p#(p(b(a(x0)),x1),p(x2,x3)) = [0 2 0]x0 + [2 1 0]x2 + [1 2 1]x3 + [2] >= [0 1 0]x2 + [1 0 0]x3 + [1] = p#(x3,a(x2)) p#(p(b(a(x0)),x1),p(x2,x3)) = [0 2 0]x0 + [2 1 0]x2 + [1 2 1]x3 + [2] >= [0 2 0]x0 + [0 0 1]x3 = p#(p(x3,a(x2)),p(b(a(x1)),b(x0))) [0 0 0] [0 0 0] [0 0 0] [0 0 0] [0] [0 0 0] [0 0 0] [0 0 0] [0 0 0] [0] p(p(b(a(x0)),x1),p(x2,x3)) = [0 4 0]x0 + [1 2 1]x1 + [4 2 1]x2 + [2 4 2]x3 + [4] >= [0 4 0]x0 + [0 2 0]x1 + [0 2 0]x2 + [2 1 2]x3 + [4] = p(p(x3,a(x2)),p(b(a(x1)),b(x0))) [0 0 0] [0 0 0] [0 0 0] [0 0 0] [0] [0 0 0] [0 0 0] [0 0 0] [0 0 0] [0] problem: DPs: TRS: p(p(b(a(x0)),x1),p(x2,x3)) -> p(p(x3,a(x2)),p(b(a(x1)),b(x0))) Qed