Why $\prod_{i\in I} \Bbb Z$ is not a projective $\Bbb Z$-module?
2719
Why isn't an infinite direct product of copies of $\Bbb Z$ a free module?
39728
integral cohomology ring of real projective space
43230
Is $\langle1-i\rangle$ a maximal ideal in $\mathbb{Z}[i]$?
91622
Help with proof that $\mathbb Z[i]/\langle 1 - i \rangle$ is a field.
128701
Are $\mathbb{Q}$ or $\mathbb{Z}$ flat modules?
114640
Showing that an ideal is not a free $R-$module.
40705
If $M$ is an $R$-module and $I\subseteq\mathrm{Ann}(M)$ an ideal, then $M$ has a structure of $R/I$-module
24561
$\mathbb S_n$ as semidirect product
153664
When is $\Bbb{Z[\zeta_n]}$ a PID?
130159
Meaning of ring notation $\Bbb Z_{(p)}$ in commutative algebra [localization]
40996
Proving that free modules are flat (without appealing projective modules)
133019
Nilpotent elements in $\mathbb Z_n$
78118
Algebraically, why is $\mathbb{Z}[i]/(i + 1)$ isomorphic to $\mathbb{Z}_{2}$?
128711
$(\Bbb Z\oplus \Bbb Z)[X] \not\cong \Bbb Z[X]\oplus \Bbb Z[X]\,$?
128732
$\mathbb Z_{p^n}$ is not the direct product of any family of its proper subgroups
8417
Natural $(R/I)$-module structure for an $R$-module $M$ annihilated by $I$
145752
Aut $\mathbb Z_p\simeq \mathbb Z_{p-1}$