Q$2$ Context$-$free languages are closed under

$1$ Point

$($previous version asked about what we have proved until that point, now we covered a

decisive result for each one of these$)$

union

intersection

complement

concatenation

Kleene star

intersection with a regular language $($that is$,$ if $C$ is context$-$free and $R$ is regular then

$CR$ is context$-$free$)$