TRS: { a__dbl(0()) -> 0(), a__dbl(s(X)) -> s(s(dbl(X))), a__dbls(nil()) -> nil(), a__dbls(cons(X, Y)) -> cons(dbl(X), dbls(Y)), a__sel(0(), cons(X, Y)) -> mark(X), a__sel(s(X), cons(Y, Z)) -> a__sel(mark(X), mark(Z)), a__indx(nil(), X) -> nil(), a__indx(cons(X, Y), Z) -> cons(sel(X, Z), indx(Y, Z)), a__from(X) -> cons(X, from(s(X))), mark(dbl(X)) -> a__dbl(mark(X)), mark(dbls(X)) -> a__dbls(mark(X)), mark(sel(X1, X2)) -> a__sel(mark(X1), mark(X2)), mark(indx(X1, X2)) -> a__indx(mark(X1), X2), mark(from(X)) -> a__from(X), mark(0()) -> 0(), mark(s(X)) -> s(X), mark(nil()) -> nil(), mark(cons(X1, X2)) -> cons(X1, X2), a__dbl(X) -> dbl(X), a__dbls(X) -> dbls(X), a__sel(X1, X2) -> sel(X1, X2), a__indx(X1, X2) -> indx(X1, X2), a__from(X) -> from(X)} Fail