Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Abstract blowing down   Assume that $X$ is a surface over an algebraically closed field $k$. Let
$\tilde{X}$ be obtained from $X$ by blowing up a smooth point and let $L$ be
the exceptional curve. Let $\coh(X)$ be the category of coherent sheaves on
$X$. In this note we show how to recover $\coh({X})$ from $\coh(\tilde{X})$, if
we know the object $\Oscr_L(L)$.

22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci