Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reducible Quantum Electrodynamics. I. The Quantum Dimension of the
  Electromagnetic Field   In absence of currents and charges the quantized electromagnetic field can be
described by wave functions which for each individual wave vector are
normalized to one. The resulting formalism involves reducible representations
of the Canonical Commutation Relations. The corresponding paradigm is a
space-time filled with two-dimensional quantum harmonic oscillators.
Mathematically, this is equivalent with two additional dimensions penetrated by
the electromagnetic waves.

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The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
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The categories of this paper are: eess
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph