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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),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)) gcd#(s(x),s(y)) -> le#(y,x) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> minus#(x,y) if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) if_gcd#(false(),s(x),s(y)) -> minus#(y,x) if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) 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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) TDG 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)) gcd#(s(x),s(y)) -> le#(y,x) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> minus#(x,y) if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) if_gcd#(false(),s(x),s(y)) -> minus#(y,x) if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) 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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) graph: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) -> gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) -> gcd#(s(x),s(y)) -> le#(y,x) if_gcd#(false(),s(x),s(y)) -> minus#(y,x) -> minus#(x,s(y)) -> pred#(minus(x,y)) if_gcd#(false(),s(x),s(y)) -> minus#(y,x) -> minus#(x,s(y)) -> minus#(x,y) if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) -> gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) -> gcd#(s(x),s(y)) -> le#(y,x) if_gcd#(true(),s(x),s(y)) -> minus#(x,y) -> minus#(x,s(y)) -> pred#(minus(x,y)) if_gcd#(true(),s(x),s(y)) -> minus#(x,y) -> minus#(x,s(y)) -> minus#(x,y) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) -> if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) -> if_gcd#(false(),s(x),s(y)) -> minus#(y,x) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) -> if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) -> if_gcd#(true(),s(x),s(y)) -> minus#(x,y) gcd#(s(x),s(y)) -> le#(y,x) -> le#(s(x),s(y)) -> le#(x,y) minus#(x,s(y)) -> minus#(x,y) -> minus#(x,s(y)) -> pred#(minus(x,y)) minus#(x,s(y)) -> minus#(x,y) -> minus#(x,s(y)) -> minus#(x,y) le#(s(x),s(y)) -> le#(x,y) -> le#(s(x),s(y)) -> le#(x,y) SCC Processor: #sccs: 3 #rules: 5 #arcs: 16/81 DPs: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> gcd#(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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) Usable Rule Processor: DPs: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> gcd#(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) Arctic Interpretation Processor: dimension: 1 usable rules: minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) pred(s(x)) -> x interpretation: [if_gcd#](x0, x1, x2) = 1x1 + x2, [gcd#](x0, x1) = 1x0 + x1, [minus](x0, x1) = x0 + x1, [pred](x0) = x0, [false] = 1, [s](x0) = 2x0, [true] = 1, [le](x0, x1) = 2x1 + 0, [0] = 1 orientation: if_gcd#(false(),s(x),s(y)) = 3x + 2y >= 2x + 1y = gcd#(minus(y,x),s(x)) gcd#(s(x),s(y)) = 3x + 2y >= 3x + 2y = if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) = 3x + 2y >= 1x + 2y = gcd#(minus(x,y),s(y)) minus(x,0()) = x + 1 >= x = x minus(x,s(y)) = x + 2y >= x + y = pred(minus(x,y)) pred(s(x)) = 2x >= x = x le(0(),y) = 2y + 0 >= 1 = true() le(s(x),0()) = 3 >= 1 = false() le(s(x),s(y)) = 4y + 0 >= 2y + 0 = le(x,y) problem: DPs: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> gcd#(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) Restore Modifier: DPs: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> gcd#(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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) Usable Rule Processor: DPs: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) TRS: le(0(),y) -> true() le(s(x),0()) -> false() le(s(x),s(y)) -> le(x,y) minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) pred(s(x)) -> x Arctic Interpretation Processor: dimension: 1 usable rules: le(0(),y) -> true() le(s(x),0()) -> false() le(s(x),s(y)) -> le(x,y) minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) pred(s(x)) -> x interpretation: [if_gcd#](x0, x1, x2) = x0 + x1 + 0, [gcd#](x0, x1) = x0 + 0, [minus](x0, x1) = x0 + 0, [pred](x0) = x0 + 0, [false] = 0, [s](x0) = 1x0 + 2, [true] = 1, [le](x0, x1) = x1 + 1, [0] = 0 orientation: gcd#(s(x),s(y)) = 1x + 2 >= 1x + 2 = if_gcd#(le(y,x),s(x),s(y)) if_gcd#(true(),s(x),s(y)) = 1x + 2 >= x + 0 = gcd#(minus(x,y),s(y)) le(0(),y) = y + 1 >= 1 = true() le(s(x),0()) = 1 >= 0 = false() le(s(x),s(y)) = 1y + 2 >= y + 1 = le(x,y) minus(x,0()) = x + 0 >= x = x minus(x,s(y)) = x + 0 >= x + 0 = pred(minus(x,y)) pred(s(x)) = 1x + 2 >= x = x problem: DPs: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) TRS: le(0(),y) -> true() le(s(x),0()) -> false() le(s(x),s(y)) -> le(x,y) minus(x,0()) -> x minus(x,s(y)) -> pred(minus(x,y)) pred(s(x)) -> x Restore Modifier: DPs: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) SCC Processor: #sccs: 0 #rules: 0 #arcs: 4/1 DPs: minus#(x,s(y)) -> minus#(x,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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) Subterm Criterion Processor: simple projection: pi(minus#) = 1 problem: DPs: 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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) Qed DPs: le#(s(x),s(y)) -> le#(x,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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) Subterm Criterion Processor: simple projection: pi(le#) = 1 problem: DPs: 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)) gcd(0(),y) -> y gcd(s(x),0()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) Qed