TRS: { a__zeros() -> cons(0(), zeros()), a__U11(tt(), L) -> s(a__length(mark(L))), a__and(tt(), X) -> mark(X), a__isNat(0()) -> tt(), a__isNat(length(V1)) -> a__isNatList(V1), a__isNat(s(V1)) -> a__isNat(V1), a__isNatIList(V) -> a__isNatList(V), a__isNatIList(zeros()) -> tt(), a__isNatIList(cons(V1, V2)) -> a__and(a__isNat(V1), isNatIList(V2)), a__isNatList(nil()) -> tt(), a__isNatList(cons(V1, V2)) -> a__and(a__isNat(V1), isNatList(V2)), a__length(nil()) -> 0(), a__length(cons(N, L)) -> a__U11(a__and(a__isNatList(L), isNat(N)), L), mark(zeros()) -> a__zeros(), mark(U11(X1, X2)) -> a__U11(mark(X1), X2), mark(length(X)) -> a__length(mark(X)), mark(and(X1, X2)) -> a__and(mark(X1), X2), mark(isNat(X)) -> a__isNat(X), mark(isNatList(X)) -> a__isNatList(X), mark(isNatIList(X)) -> a__isNatIList(X), mark(cons(X1, X2)) -> cons(mark(X1), X2), mark(0()) -> 0(), mark(tt()) -> tt(), mark(s(X)) -> s(mark(X)), mark(nil()) -> nil(), a__zeros() -> zeros(), a__U11(X1, X2) -> U11(X1, X2), a__length(X) -> length(X), a__and(X1, X2) -> and(X1, X2), a__isNat(X) -> isNat(X), a__isNatList(X) -> isNatList(X), a__isNatIList(X) -> isNatIList(X)} Fail