Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 50468

Algebraic varieties, stacks, sheaves, schemes, moduli spaces, complex geometry, quantum cohomology.

7 votes
1 answer
1k views

Automorphism groups of Hirzebruch surfaces

The Hirzebruch surfaces are the $\mathbb{P}^1$ bundles $\mathbb{F_n}$ ($n\geqslant 0$) which can be obtained projectivizing the rank $2$ vector bundles $\mathcal{O}_{\mathbb{P}^1}\oplus \mathcal{O}_{\ …
amateur's user avatar
  • 375
2 votes
1 answer
182 views

The target of a regular function in Non-archimedean analytic geometry

Let $(k,|\cdot|)$ be an algebraically closed field, complete wrt a (multiplicative) norm as in the framework of the Berkovich's analytic geometry. Given a commutative Banach $k$-algebra $\mathcal{A}\ …
amateur's user avatar
  • 375
1 vote
Accepted

The variety induced by an extension of a field

I decided to turn my comment into an answer not because it is complete but because I think it can be of use. Let $z=(z_0:z_1:z_2)$ and $u=(u_1:\ldots:u_k)$ be homogeneous coordinates of $\mathbb{P}^2$ …
amateur's user avatar
  • 375
1 vote

Scheme-theoretic image and delta-invariants

Without any stronger hypothesis connecting $f$ and $g$ you should not expect that to happen. The simplest instance is when $(X,o)$ is alrealdy non singular, say dimension 2: $(\mathbb{C}^2,o)$. In thi …
amateur's user avatar
  • 375
1 vote
2 answers
121 views

Rank of a linear combination of linear operators

I asked this question a few days ago in MathExchange and received no satisfatory answer. I hope it is well suited for MathOverflow. Suppose I have two linear operators $X,\,Y$ on $\mathbb{C}^n$. Now l …
amateur's user avatar
  • 375
8 votes
Accepted

General conditions for normality of blow-up

Let $X=Spec(R)$. Blowing-up $Z=V(I)$ is the same as to look at $Proj$ of the graded ring $R[It]=\oplus_{j\geqslant 0} I^jt^j\subset R[t]$, the Rees ring associated to $I$. Assume $R$ is a domain, inte …
amateur's user avatar
  • 375