Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the signed graphs with two distinct eigenvalues   We consider signed graphs, i.e, graphs with positive or negative signs on
their edges. We construct some families of bipartite signed graphs with only
two distinct eigenvalues. This leads to constructing infinite families of
regular bipartite Ramanujan graphs.

24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc