Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectrum of the Hermitian Wilson-Dirac Operator for a Uniform Magnetic
  Field in Two Dimensions   It is shown that the eigenvalue problem for the hermitian Wilson-Dirac
operator of for a uniform magnetic field in two dimensions can be reduced to
one-dimensional problem described by a relativistic analog of the Harper
equation. An explicit formula for the secular equations is given in term of a
set of polynomials. The spectrum exhibits a fractal structure in the infinite
volume limit. An exact result concerning the index theorem for the overlap
Dirac operator is obtained.

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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas