862 quite useful. For example if we want to match the name of

   862 quite useful. For example if we want to match the name of

   863 an email we might use the regular expression

   863 an email we might use the regular expression

   864 

   864 

   865 \[

   865 \[

   866 (name: [a\mbox{-}z0\mbox{-}9\_\!\_\,.-]^+)\cdot @\cdot 

   866 (name: [a\mbox{-}z0\mbox{-}9\_\!\_\,.-]^+)\cdot @\cdot 

   868 (top\_level: [a\mbox{-}z\,.]^{\{2,6\}})

   868 (top\_level: [a\mbox{-}z\,.]^{\{2,6\}})

   869 \]

   869 \]

   870 

   870 

   871 \noindent Then if we match the email address

   871 \noindent Then if we match the email address

   872 

   872