Definition 18.2.2 (Borel $\sigma$-Algebra on $\ol{\real}$).label The family
\[\cb_{\ol{\real}}= \bracsn{E \subset \ol \real| E \cap \real \in \cb_\real}\]
is the Borel $\sigma$-algebra on $\ol{\real}$.
Definition 18.2.2 (Borel $\sigma$-Algebra on $\ol{\real}$).label The family
is the Borel $\sigma$-algebra on $\ol{\real}$.