Neither (1) nor (2) alone is sufficient for (3) to hold.
Thus $A$ is neither symmetric nor positive.
Both $X$ and $Y$ are countable, but neither is finite.
Neither of them is finite.
[Use neither when there are two alternatives; if there are more, use none.]
Let $u$ and $v$ be two distributions neither of which has compact support.
As shown in Figure 3, neither curve intersects $X$.
In neither case can $f$ be smooth. [Note the inversion after the negative clause.]
Both proofs are easy, so we give neither.
Thus $X$ is not finite; neither $\langle$nor$\rangle$ is $Y$.
Neither is the problem simplified by assuming $f=g$.