Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Moduli spaces of vector bundles on a singular rational ruled surface   We study moduli spaces $M_X(r,c_1,c_2)$ parametrizing slope semistable vector
bundles of rank $r$ and fixed Chern classes $c_1, c_2$ on a ruled surface whose
base is a rational nodal curve. We show that under certain conditions, these
moduli spaces are irreducible, smooth and rational (when non-empty). We also
prove that they are non-empty in some cases.
  We show that for a rational ruled surface defined over real numbers, the
moduli space $M_X(r,c_1,c_2)$ is rational as a variety defined over $\mathbb
R$.

30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin