Search Results
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 |
8
votes
Accepted
Resolution of a torsion sheaf
Write the equation of $C$ as $\ XY-Z^2=0$, and consider the homomorphism $u: \mathcal{O}_{\mathbb{P}^2}(-1)^2\rightarrow \mathcal{O}_{\mathbb{P}^2}^2$ given by the matrix $\begin{pmatrix}
X & Z\\Z& Y
…
4
votes
Accepted
Is the projective dimension of finite torsion-free modules over regular ring of dimension $n...
Yes. If $\operatorname{pd}_A(M)=n $, there exists a maximal ideal $\mathfrak{m}$ of $A$ such that $\operatorname{pd}_{A_{\mathfrak{m}}}(M_{\mathfrak{m}})=n $. By the Auslander-Buchsbaum theorem, this …
2
votes
Accepted
Homological dimension of pure coherent sheaves and specialization
Take for $X$ the plane curve $X^3=Y^2T$, and for $F$ the ideal sheaf $(X-\pi ^2T,Y-\pi ^3T)$. Its restriction to the generic fiber is the ideal of a smooth point, hence is an invertible sheaf, while …