MathOverflow

If $\mathcal{A}$ and $\mathcal{B}$ are Boolean algebras, a homomorphism $i: \mathcal{A} \to \mathcal{B}$ is complete iff whenever $S \subset \mathcal{A}$ and $\bigvee S$ exists, then $\bigvee(i''S)$ exists in $\mathcal{B}$ and $\bigvee(i''S) = i\big...

Ref 1: How big a box can you wrap with a given polygon?
Ref 2: 'Trapping' 3D regions with sheets of paper
We look at wrapping 3d solid bodies with any given sheet of paper which is a polygonal or planar region. Once a solid is wrapped, any path to any point on its surface from any far away point in space will have to cut thru the paper sheet at least once...

(Main)Problem:
Let $X$ be a real or complex Banach space. $X$ satisfies:There exists real or complex series $\{a_k\}_{k=1}^n,\{b_k\}_{k=1}^n$ which satisfies that:$\begin{cases} a_k,b_k\in \mathbb{R}\ \forall k=1,\dots n,\ \sum_{k=1}^n a_k b_k =\frac{1}{2},& \text...

There might be just enough time to pick another location, but I am curious what mathematicians think.
Should the 2022 ICM take place in Russia?
Will Ukrainian mathematicians be able to attend a conference in Russia if Russia no longer recognizes their passports?...