Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Singular 7-manifolds with G_2 holonomy and intersecting 6-branes   A 7-manifold with G_2 holonomy can be constructed as a R^3 bundle over a
quaternionic space. We consider a quaternionic base space which is singular and
its metric depends on three parameters, where one of them corresponds to an
interpolation between S^4 and CP^2 or its non-compact analogs. This 4-d
Einstein space has four isometries and the fixed point set of a generic Killing
vector is discussed. When embedded into M-theory the compactification over a
given Killing vector gives intersecting 6-branes as IIA configuration and we
argue that membrane instantons may resolve the curvature singularity.

2
The categories of this paper are: math
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat