YES Problem: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) Proof: DP Processor: DPs: lt#(s(x),s(y)) -> lt#(x,y) logarithm#(x) -> lt#(0(),x) logarithm#(x) -> ifa#(lt(0(),x),x) ifa#(true(),x) -> help#(x,1()) help#(x,y) -> lt#(y,x) help#(x,y) -> ifb#(lt(y,x),x,y) ifb#(true(),x,y) -> half#(x) ifb#(true(),x,y) -> help#(half(x),s(y)) half#(s(s(x))) -> half#(x) TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) TDG Processor: DPs: lt#(s(x),s(y)) -> lt#(x,y) logarithm#(x) -> lt#(0(),x) logarithm#(x) -> ifa#(lt(0(),x),x) ifa#(true(),x) -> help#(x,1()) help#(x,y) -> lt#(y,x) help#(x,y) -> ifb#(lt(y,x),x,y) ifb#(true(),x,y) -> half#(x) ifb#(true(),x,y) -> help#(half(x),s(y)) half#(s(s(x))) -> half#(x) TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) graph: half#(s(s(x))) -> half#(x) -> half#(s(s(x))) -> half#(x) ifb#(true(),x,y) -> half#(x) -> half#(s(s(x))) -> half#(x) ifb#(true(),x,y) -> help#(half(x),s(y)) -> help#(x,y) -> ifb#(lt(y,x),x,y) ifb#(true(),x,y) -> help#(half(x),s(y)) -> help#(x,y) -> lt#(y,x) help#(x,y) -> ifb#(lt(y,x),x,y) -> ifb#(true(),x,y) -> help#(half(x),s(y)) help#(x,y) -> ifb#(lt(y,x),x,y) -> ifb#(true(),x,y) -> half#(x) help#(x,y) -> lt#(y,x) -> lt#(s(x),s(y)) -> lt#(x,y) ifa#(true(),x) -> help#(x,1()) -> help#(x,y) -> ifb#(lt(y,x),x,y) ifa#(true(),x) -> help#(x,1()) -> help#(x,y) -> lt#(y,x) logarithm#(x) -> ifa#(lt(0(),x),x) -> ifa#(true(),x) -> help#(x,1()) logarithm#(x) -> lt#(0(),x) -> lt#(s(x),s(y)) -> lt#(x,y) lt#(s(x),s(y)) -> lt#(x,y) -> lt#(s(x),s(y)) -> lt#(x,y) SCC Processor: #sccs: 3 #rules: 4 #arcs: 12/81 DPs: ifb#(true(),x,y) -> help#(half(x),s(y)) help#(x,y) -> ifb#(lt(y,x),x,y) TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) Usable Rule Processor: DPs: ifb#(true(),x,y) -> help#(half(x),s(y)) help#(x,y) -> ifb#(lt(y,x),x,y) TRS: half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) Arctic Interpretation Processor: dimension: 1 usable rules: half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) interpretation: [ifb#](x0, x1, x2) = -2x0 + x1 + -16, [help#](x0, x1) = x0 + 0, [half](x0) = -1x0 + 0, [false] = 0, [true] = 3, [lt](x0, x1) = x1 + 2, [s](x0) = 1x0 + 4, [0] = 0 orientation: ifb#(true(),x,y) = x + 1 >= -1x + 0 = help#(half(x),s(y)) help#(x,y) = x + 0 >= x + 0 = ifb#(lt(y,x),x,y) half(0()) = 0 >= 0 = 0() half(s(0())) = 3 >= 0 = 0() half(s(s(x))) = 1x + 4 >= x + 4 = s(half(x)) lt(0(),s(x)) = 1x + 4 >= 3 = true() lt(x,0()) = 2 >= 0 = false() lt(s(x),s(y)) = 1y + 4 >= y + 2 = lt(x,y) problem: DPs: help#(x,y) -> ifb#(lt(y,x),x,y) TRS: half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) Restore Modifier: DPs: help#(x,y) -> ifb#(lt(y,x),x,y) TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) SCC Processor: #sccs: 0 #rules: 0 #arcs: 2/1 DPs: lt#(s(x),s(y)) -> lt#(x,y) TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) Subterm Criterion Processor: simple projection: pi(lt#) = 1 problem: DPs: TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) Qed DPs: half#(s(s(x))) -> half#(x) TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) Subterm Criterion Processor: simple projection: pi(half#) = 0 problem: DPs: TRS: lt(0(),s(x)) -> true() lt(x,0()) -> false() lt(s(x),s(y)) -> lt(x,y) logarithm(x) -> ifa(lt(0(),x),x) ifa(true(),x) -> help(x,1()) ifa(false(),x) -> logZeroError() help(x,y) -> ifb(lt(y,x),x,y) ifb(true(),x,y) -> help(half(x),s(y)) ifb(false(),x,y) -> y half(0()) -> 0() half(s(0())) -> 0() half(s(s(x))) -> s(half(x)) Qed