Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological quantization of gravitational fields as generalized harmonic
  maps   We apply the topological quantization method to some gravitational fields
which can be represented as generalized harmonic maps. This representation
extends the well-known concept of harmonic maps and allows us to describe some
solutions to the Einstein field equations as generalized strings, where the
base space for the generalized harmonic map is a two-dimensional manifold. The
results obtained here point to an incompatibility of the classical description
of the gravitational field and its symmetries with a discretization of the
parameters that enter in its description.

33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th