Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Monte Carlo simulation of Ising model on directed Barabasi-Albert
  network   The existence of spontaneous magnetization of Ising spins on directed
Barabasi-Albert networks is investigated with seven neighbors, by using Monte
Carlo simulations. In large systems we see the magnetization for different
temperatures T to decay after a characteristic time tau, which is extrapolated
to diverge at zero temperature.

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The categories of this paper are: patt-sol
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The categories of this paper are: astro-ph
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The categories of this paper are: physics
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an