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\chapter[$\ds\bigcap_{y > 0,\, y \in \bbr}A_y =$ \underline{\hspace{30mm}}.]{Prove that $\ds\bigcap_{y > 0,\, y \in \bbr}A_y =$ \underline{\hspace{30mm}},}

where $A_y = (-y,y) \subseteq \bbr$ is an open interval. It is up to you to determine the set on the right and to prove the equality. If possible, determine the set on the right explicitly.

\section{First draft}
Due Wednesday, March 9 at 6:00 PM.

\begin{proof}

\end{proof}