Decidability of fullness of intersection of a CSL with a regular language Let $L_r$ be a regular language with alphabet $\Sigma$ and $L_{\text{csl}}$ be a context sensitive language. Are any of the following questions decidable?


$L_r \cap L_\text{csl} \stackrel{?}{=} L_r$
$\Sigma^* \cap L_\text{csl} \stackrel{?}{=} L_r$
$L_r \cap L_\text{csl} \stackrel{?}{=} \Sigma^*$
$\Sigma^* \cap L_\text{csl} \stackrel{?}{=} \Sigma^*$


I understand that (1) implies the others. I am also looking for any "near variants" that might be decidable.
It is well-known that universality of context-free language is undecidable, making all your items undecidable already for context-free languages, so a fortiori for context sensitive languages (the particular case $L_r=\Sigma^*$ is already undecidable in all items).