Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Periodic Jacobi Matrices on Trees   We begin the systematic study of the spectral theory of periodic Jacobi
matrices on trees including a formal definition. The most significant result
that appears here for the first time is that these operators have no singular
continuous spectrum. We review important previous results of Sunada and Aomoto
and present several illuminating examples. We present many open problems and
conjectures that we hope will stimulate further work.

31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
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The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas