I'm reading topology of Munkres and I have a problem that stuck me for a while. I'm so greatful if anyone can help me with this.
Let $A$ be a proper subset of $X$, and let $B$ is a proper subset of $Y$. If $X$ and $Y$ are connected, show that $$(X\times Y) \setminus (A\times B)$$ is connected.
Thanks so much for your consideration ^^