Is the increasing union of $\sigma$-algebras a $\sigma$-algebra?
19996
Example where union of increasing sigma algebras is not a sigma algebra
137446
Show that if $b_k\uparrow \infty$ and $\Sigma_{k = 1}^\infty a_kb_k$ converges, then $b_m \Sigma_{k = m}^\infty a_k → 0$ as $m → \infty$.
150287
Spectral radii and norms of similar elements in a C*-algebra: $\|bab^{-1}\|<1$ if $b=(\sum_{n=0}^\infty (a^*)^n a^n)^{1/2}$
80735
Show that $C_0([a, b], \mathbb{R})$ is not $\sigma$-compact
137815
Additive but not $\sigma$-additive function
87203
Preimage of generated $\sigma$-algebra
136083
Show that $\sigma\circ\phi : G_1 \to G_3$ is an isomorphism
40321
$\operatorname{Aut}(\mathbb Z_n)$ is isomorphic to $U_n$.
146951
Every countably generated sigma algebra is generated by a random variable
7007
If $\alpha$ is a regular cardinal, the union of an elementary chain of $\alpha$-saturated models is also a $\alpha$-saturated model
16048
Approximating a $\sigma$-algebra by a generating algebra
146006
Uncountable $\sigma$-algebra
153306
Number of sigma algebras for set with 4 elements
142145
strictly positive elements in $C^*$-algebra
103307
Generate the smallest $\sigma$-algebra containing a given family of sets
134983
Borel sigma algebra not containing all subsets of $\mathbb{R}$?
115860
Is a measure for a sigma algebra determined by its values for a generator of the sigma algebra?