Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological Charges of Noncommutative Soliton   The noncommutative soliton is characterized by the use of the projection
operators in non-commutative space. By using the close relation with the
K-theory of $C^*$-algebra, we consider the variations of projection operators
along the commutative directions and identify their topological charges. When
applied to the string theory, it gives the modification of the brane charges
due to tachyon background.

30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
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
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org