Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Elementary Divisors of the Incidence Matrices of Skew Lines in
  PG(3,p)   The elementary divisors of the incidence matrices of lines in $PG(3,p)$ are
computed, where two lines are incident if and only if they are skew.

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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat
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The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga