Calculate the Pontragin dual $\text{Hom}_{\mathbb{Z}}(\mathbb{Q}/\mathbb{Z}, \mathbb{Q}/\mathbb{Z})$.
124230
What is $\operatorname{Hom}_\mathbb{Z}(\mathbb{Q}/\mathbb{Z},\mathbb{Q}/\mathbb{Z})$?
42213
Computing $\text{Gal}(\mathbb{Q}^{ab}/\mathbb{Q})$
66020
What is $\mathbb Z[[t]]$? What are the double brackets?
20097
Cardinality of the quotient ring $\mathbb{Z}[x]/(x^2-3,2x+4)$
67772
How to find $k$ such that $(\mathbb{Z} \times \mathbb{Z})/ \langle (m,n)\rangle \cong \mathbb{Z} \times \mathbb{Z}_k$
137029
Prove that $\operatorname{Hom}_{\Bbb{Z}}(\Bbb{Q},\Bbb{Z}) = 0$ and show that $\Bbb{Q}$ is not a projective $\Bbb{Z}$-module.
77903
Finding the integral closure of $\mathbb{Z}$ in $\mathbb{Q}[i]$
105363
$\mathbb Z^n/\langle (a,...,a) \rangle \cong \mathbb Z^{n-1} \oplus \mathbb Z/\langle a \rangle$
87750
Hom / tensor adjunction for $O_X$ modules?
108775
Identify the ring $\mathbb {Z}[i]/(2 + i) $
103544
Determine a formula for a dual basis.
57434
$SL_2(\mathbb Z_3)/Z(SL_2(\mathbb Z_3)) \cong A_4$
97009
Image of ring homomorphism $\phi : \mathbb{Z}[t] \to \mathbb{Q}$?
66313
$\mathbb{Z}[i]/(a+bi) \cong \mathbb{Z}_{a^2+b^2}$ if $(a,b)=1$
147827
How to calculate $|\operatorname {SL}_2(\mathbb Z/N\mathbb Z)|$?
19310
Identify the ring $\mathbb{Z}[x]/(2x)$
94382
Calculate the degree of the extension $[\mathbb{Q}(\cos(\frac{2\pi}{p})):\mathbb{Q}]$