Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coloring problem of signed interval graphs   The chromatic number of signed graphs is defined recently. The coloring and
clique problem of interval graphs has been studied and polynomial time
algorithms are established. Here we consider these problems for signed interval
graphs and prove that the coloring problem of signed interval graphs is
NP-complete whereas their ordinary clique problem is in P. We also study the
complexity of further related problems.

23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org
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The categories of this paper are: eess
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs