Let $Q_r = \{ z=x+iy : x,y \in (-r,r) \} \subseteq \mathbb C$
Show that $Q_4 \backslash Q_1$ isn't simply connected domain.
Let $Q_r = \{ z=x+iy : x,y \in (-r,r) \} \subseteq \mathbb C$
Show that $Q_4 \backslash Q_1$ isn't simply connected domain.