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Minseon Shin's user avatar
Minseon Shin's user avatar
Minseon Shin's user avatar
Minseon Shin
  • Member for 13 years, 3 months
  • Last seen this week
8 votes
Accepted

Does taking sections commute with base change?

8 votes

Kummer sequence etale topology

7 votes
Accepted

Can we classify all finitely generated projective modules over $k[x,y,x^{-1},y^{-1}]$?

6 votes
Accepted

For $n>1$ and a ring $R$ s.t. $k[x_1,\dots, x_n]\subset R\subset k(x_1,\dots, x_n)$ is $R$ a localization of $k[x_1,\dots, x_n]$?

5 votes
Accepted

Is there a surjective morphism $\widehat{\Bbb Z} \to \Bbb Z$?

5 votes
Accepted

Can $A[x]$ be isomorphic to $A$ if $A$ is noetherian?

4 votes
Accepted

Why is this map from Leray spectral sequence zero?

4 votes
Accepted

On $A$ algebra homomorphisms $A[[X_1,...,X_n]]\to Q(A)$, where $A$ is a complete DVR

4 votes
Accepted

For ideals $\mathfrak{a,b}$ if a solution $\mathfrak{c}$ to $\mathfrak{cb}=\mathfrak{a}$ exists, is it unique and equal $(\mathfrak{a}:\mathfrak{b})$?

4 votes
Accepted

Is there an example that $\mathcal{O}(\mathrm{Proj}\,B)\neq B_0$ for some graded ring $B$?

4 votes

Nonaffines must base change to nonaffines

4 votes
Accepted

Hartshorne Exercise III 6.2 (a)

4 votes
Accepted

If $M$ is a finite length module over a noetherian local ring $R$, then is $\mathrm{Ext}_R^i(M, R)$ finite length as well?

4 votes
Accepted

A connected ring $A$ such that $A[1/f]$ is disconnected

4 votes
Accepted

Cardinality of general linear group of finite rings

4 votes

Is every integral point of an arithmetic scheme contained in an affine open set?

3 votes
Accepted

Prove that $G = \prod_{p\hspace{1mm} prime}\frac{\mathbb{Z}}{p\mathbb{Z}}$ is not isomorphic to $\frac{G}{torsion(G)} \bigoplus torsion(G)$.

3 votes
Accepted

Long exact sequence of hyperhomology

3 votes
Accepted

Inverse/Direct Images and Sheafification

3 votes
Accepted

connectedness can be checked on special fibre

3 votes
Accepted

Pushforward of equivariant sheaf

3 votes
Accepted

every ideal in a Noetherian ring is an intersection of ideals primary to maximal ideals?

3 votes

If $X$ is such that any étale $X$-scheme is locally factorial, is any smooth $X$-scheme locally factorial?

3 votes
Accepted

Is there a non-regular depth 1 noetherian local ring with this property?

3 votes
Accepted

Is finite dimensional central division algebra = $\otimes$(proper central division subalgebra)?

2 votes
Accepted

Length of a tensor product with an extension of a field

2 votes

Surjective etale morphism from an open subscheme.

2 votes
Accepted

Is the completion of regular ring regular?

2 votes

Find all $x,y$ such that $x^3+5y^3=(a^3+5b^3)^3$.

2 votes
Accepted

Infinitesimal neighborhoods of an affine bundle