Problem: and(tt(),T) -> T isNatIList(IL) -> isNatList(activate(IL)) isNat(n__0()) -> tt() isNat(n__s(N)) -> isNat(activate(N)) isNat(n__length(L)) -> isNatList(activate(L)) isNatIList(n__zeros()) -> tt() isNatIList(n__cons(N,IL)) -> and(isNat(activate(N)),isNatIList(activate(IL))) isNatList(n__nil()) -> tt() isNatList(n__cons(N,L)) -> and(isNat(activate(N)),isNatList(activate(L))) isNatList(n__take(N,IL)) -> and(isNat(activate(N)),isNatIList(activate(IL))) zeros() -> cons(0(),n__zeros()) take(0(),IL) -> uTake1(isNatIList(IL)) uTake1(tt()) -> nil() take(s(M),cons(N,IL)) -> uTake2(and(isNat(M),and(isNat(N),isNatIList(activate(IL)))),M,N,activate(IL)) uTake2(tt(),M,N,IL) -> cons(activate(N),n__take(activate(M),activate(IL))) length(cons(N,L)) -> uLength(and(isNat(N),isNatList(activate(L))),activate(L)) uLength(tt(),L) -> s(length(activate(L))) 0() -> n__0() s(X) -> n__s(X) length(X) -> n__length(X) zeros() -> n__zeros() cons(X1,X2) -> n__cons(X1,X2) nil() -> n__nil() take(X1,X2) -> n__take(X1,X2) activate(n__0()) -> 0() activate(n__s(X)) -> s(activate(X)) activate(n__length(X)) -> length(activate(X)) activate(n__zeros()) -> zeros() activate(n__cons(X1,X2)) -> cons(activate(X1),X2) activate(n__nil()) -> nil() activate(n__take(X1,X2)) -> take(activate(X1),activate(X2)) activate(X) -> X Proof: Unfolding Processor: loop length: 4 terms: isNatIList(activate(n__zeros())) isNatIList(zeros()) isNatIList(cons(0(),n__zeros())) isNatIList(n__cons(0(),n__zeros())) context: and(isNat(activate(0())),[]) substitution: Qed