Would the complement of the set of positive numbers union the set of negative numbers be an empty set or 0

Question

NOT(Positive numbers union negative numbers)=? 0 or empty set if the universe of discourse is all integers?

Answer 1

The union of positives and negatives do not include $0$ because $0$ is neither positive, nor negative.

Thus the complement of the union is the set {$0$}.

Answer 2

Zero is neither a positive nor a negative number. So $Z^+$ U $Z^-$ does not include zero which in result makes it's negation equals to ${0}$. Note that whenever we need to make emphasis that 0 belongs to a set it's more preferred to say Non-negative instead of positive because the non-negativity of 0 is clearer to see compared to its non-positivity.