More problems

[mky2]

This added quite a few problems but they are not well-documented yet and unorganised. Notably, we have

• $\mathscr P S\leq \mathscr P T$ implies $S \subseteq T$; and
• $\bigcap \mathscr P S = S$; and
• $\mathscr P S =\mathscr P T$ implies $S = T$.

Feedbacks are welcome.

[kbuzzard]

Many thanks! I will take a look at these today before my 8pm livestream.