3 problems

Let a locally compact group have the approximation property (AP) if there exists a generalized sequence, or net, satisfying the approximation condition for every operator coefficie…

Let $X$ and $Y$ be Banach spaces. The approximation property for $X$ is the assertion that every compact operator in $\mathcal{B}(Y,X)$ can be approximated in norm by finite-rank m…

Let $\mathfrak A$ be an algebra of subsets of $\omega$, and let $\mathfrak c$ denote the cardinality of the continuum. Cardinality obstruction conjecture. No algebra $\mathfrak A$…