YES Problem: le(0(),y) -> true() le(s(x),0()) -> false() le(s(x),s(y)) -> le(x,y) pred(s(x)) -> x minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) mod(0(),y) -> 0() mod(s(x),0()) -> 0() mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) if_mod(false(),s(x),s(y)) -> s(x) Proof: DP Processor: DPs: le#(s(x),s(y)) -> le#(x,y) minus#(x,s(y)) -> minus#(x,y) minus#(x,s(y)) -> pred#(minus(x,y)) mod#(s(x),s(y)) -> le#(y,x) mod#(s(x),s(y)) -> if_mod#(le(y,x),s(x),s(y)) if_mod#(true(),s(x),s(y)) -> minus#(x,y) if_mod#(true(),s(x),s(y)) -> mod#(minus(x,y),s(y)) TRS: le(0(),y) -> true() le(s(x),0()) -> false() le(s(x),s(y)) -> le(x,y) pred(s(x)) -> x minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) mod(0(),y) -> 0() mod(s(x),0()) -> 0() mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) if_mod(false(),s(x),s(y)) -> s(x) Usable Rule Processor: DPs: le#(s(x),s(y)) -> le#(x,y) minus#(x,s(y)) -> minus#(x,y) minus#(x,s(y)) -> pred#(minus(x,y)) mod#(s(x),s(y)) -> le#(y,x) mod#(s(x),s(y)) -> if_mod#(le(y,x),s(x),s(y)) if_mod#(true(),s(x),s(y)) -> minus#(x,y) if_mod#(true(),s(x),s(y)) -> mod#(minus(x,y),s(y)) TRS: minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) pred(s(x)) -> x le(0(),y) -> true() le(s(x),0()) -> false() le(s(x),s(y)) -> le(x,y) Matrix Interpretation Processor: dim=1 usable rules: minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) pred(s(x)) -> x interpretation: [if_mod#](x0, x1, x2) = x1 + x2 + 2, [mod#](x0, x1) = 2x0 + x1 + 2, [minus#](x0, x1) = x0 + x1, [pred#](x0) = 0, [le#](x0, x1) = 2x0, [minus](x0, x1) = x0, [pred](x0) = x0, [false] = 0, [s](x0) = 2x0 + 1/2, [true] = 0, [le](x0, x1) = 0, [0] = 0 orientation: le#(s(x),s(y)) = 4x + 1 >= 2x = le#(x,y) minus#(x,s(y)) = x + 2y + 1/2 >= x + y = minus#(x,y) minus#(x,s(y)) = x + 2y + 1/2 >= 0 = pred#(minus(x,y)) mod#(s(x),s(y)) = 4x + 2y + 7/2 >= 2y = le#(y,x) mod#(s(x),s(y)) = 4x + 2y + 7/2 >= 2x + 2y + 3 = if_mod#(le(y,x),s(x),s(y)) if_mod#(true(),s(x),s(y)) = 2x + 2y + 3 >= x + y = minus#(x,y) if_mod#(true(),s(x),s(y)) = 2x + 2y + 3 >= 2x + 2y + 5/2 = mod#(minus(x,y),s(y)) minus(x,0()) = x >= x = x minus(x,s(y)) = x >= x = pred(minus(x,y)) pred(s(x)) = 2x + 1/2 >= x = x le(0(),y) = 0 >= 0 = true() le(s(x),0()) = 0 >= 0 = false() le(s(x),s(y)) = 0 >= 0 = le(x,y) problem: DPs: TRS: minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) pred(s(x)) -> x le(0(),y) -> true() le(s(x),0()) -> false() le(s(x),s(y)) -> le(x,y) Qed