Is there a $\sigma$-algebra which has countably many elements but not finitely many?
43894
If $S$ is an infinite $\sigma$ algebra on $X$ then $S$ is not countable
51134
If $E \in \sigma(\mathcal{C})$ then there exists a countable subset $\mathcal{C}_0 \subseteq \mathcal{C}$ with $E \in \sigma(\mathcal{C}_0)$
87203
Preimage of generated $\sigma$-algebra
42582
Infinite group with only two conjugacy classes
104308
Proving a set is a Sigma Algebra
35140
Existence of minimal $\sigma$-algebra and transfinite induction
110450
probability measure on $\sigma$-algebra
146006
Uncountable $\sigma$-algebra
66301
The cardinality of the set of countably infinite subsets of an infinite set
32774
Finite Cartesian Product of Countable sets is countable?
103427
When is $\operatorname{Hom}_A(M,N)$ finitely generated?
142145
strictly positive elements in $C^*$-algebra
96892
Number of Non-isomorphic models of Set Theory
29637
$\sigma$-algebra of sets that are both $G_\delta$ and $F_\sigma$
42652
Must $k$-subalgebra of $k[x]$ be finitely generated?
81327
union of sigma algebra is sigma algebra
45939
For which $n≥2$ does there exist $\sigma\in A_n$ with $|\sigma| > n$