Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New divisors in the boundary of the instanton moduli space   Let ${\mathcal I}(n)$ denote the moduli space of rank $2$ instanton bundles
of charge $n$ on ${\mathbb P}^3$. We know from several authors that ${\mathcal
I}(n)$ is an irreducible, nonsingular and affine variety of dimension $8n-3$.
Since every rank $2$ instanton bundle on ${\mathbb P}^3$ is stable, we may
regard ${\mathcal I}(n)$ as an open subset of the projective Gieseker--Maruyama
moduli scheme ${\mathcal M}(n)$ of rank $2$ semistable torsion free sheaves $F$
on ${\mathbb P}^3$ with Chern classes $c_1=c_3=0$ and $c_2=n$, and consider the
closure $\overline{{\mathcal I}(n)}$ of ${\mathcal I}(n)$ in ${\mathcal M}(n)$.
  We construct some of the irreducible components of dimension $8n-4$ of the
boundary $\partial{\mathcal I}(n):=\overline{{\mathcal I}(n)}\setminus{\mathcal
I}(n)$. These components generically lie in the smooth locus of ${\mathcal
M}(n)$ and consist of rank $2$ torsion free instanton sheaves with
singularities along rational curves.

15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat