YES Problem: minus(x,0()) -> x minus(s(x),s(y)) -> minus(x,y) quot(0(),s(y)) -> 0() quot(s(x),s(y)) -> s(quot(minus(x,y),s(y))) plus(0(),y) -> y plus(s(x),y) -> s(plus(x,y)) plus(minus(x,s(0())),minus(y,s(s(z)))) -> plus(minus(y,s(s(z))),minus(x,s(0()))) Proof: DP Processor: DPs: minus#(s(x),s(y)) -> minus#(x,y) quot#(s(x),s(y)) -> minus#(x,y) quot#(s(x),s(y)) -> quot#(minus(x,y),s(y)) plus#(s(x),y) -> plus#(x,y) plus#(minus(x,s(0())),minus(y,s(s(z)))) -> plus#(minus(y,s(s(z))),minus(x,s(0()))) TRS: minus(x,0()) -> x minus(s(x),s(y)) -> minus(x,y) quot(0(),s(y)) -> 0() quot(s(x),s(y)) -> s(quot(minus(x,y),s(y))) plus(0(),y) -> y plus(s(x),y) -> s(plus(x,y)) plus(minus(x,s(0())),minus(y,s(s(z)))) -> plus(minus(y,s(s(z))),minus(x,s(0()))) Usable Rule Processor: DPs: minus#(s(x),s(y)) -> minus#(x,y) quot#(s(x),s(y)) -> minus#(x,y) quot#(s(x),s(y)) -> quot#(minus(x,y),s(y)) plus#(s(x),y) -> plus#(x,y) plus#(minus(x,s(0())),minus(y,s(s(z)))) -> plus#(minus(y,s(s(z))),minus(x,s(0()))) TRS: minus(x,0()) -> x minus(s(x),s(y)) -> minus(x,y) Matrix Interpretation Processor: dim=3 usable rules: minus(x,0()) -> x minus(s(x),s(y)) -> minus(x,y) interpretation: [plus#](x0, x1) = [1 0 0]x0 + [0 1 0]x1, [quot#](x0, x1) = [0 0 1]x0, [minus#](x0, x1) = [1 0 0]x0, [1 0 1] [1] [s](x0) = [1 1 0]x0 + [0] [1 0 1] [1], [1 1 1] [0 0 0] [minus](x0, x1) = [1 1 1]x0 + [0 1 0]x1 [1 0 1] [0 0 0] , [0] [0] = [0] [1] orientation: minus#(s(x),s(y)) = [1 0 1]x + [1] >= [1 0 0]x = minus#(x,y) quot#(s(x),s(y)) = [1 0 1]x + [1] >= [1 0 0]x = minus#(x,y) quot#(s(x),s(y)) = [1 0 1]x + [1] >= [1 0 1]x = quot#(minus(x,y),s(y)) plus#(s(x),y) = [1 0 1]x + [0 1 0]y + [1] >= [1 0 0]x + [0 1 0]y = plus#(x,y) plus#(minus(x,s(0())),minus(y,s(s(z)))) = [1 1 1]x + [1 1 1]y + [2 1 1]z + [1] >= [1 1 1]x + [1 1 1]y = plus#(minus(y,s(s(z))),minus(x,s(0()))) [1 1 1] minus(x,0()) = [1 1 1]x >= x = x [1 0 1] [3 1 2] [0 0 0] [2] [1 1 1] [0 0 0] minus(s(x),s(y)) = [3 1 2]x + [1 1 0]y + [2] >= [1 1 1]x + [0 1 0]y = minus(x,y) [2 0 2] [0 0 0] [2] [1 0 1] [0 0 0] problem: DPs: TRS: minus(x,0()) -> x minus(s(x),s(y)) -> minus(x,y) Qed