Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Erratum to "$B_2$-crystals: Axioms, structure, models" [J. Combin.
  Theory, Ser. A, 116 (2009), 265--289]   In this erratum we explain how to implement some axioms stated in our paper
of 2009 so as to obtain a purely "local" characterization for finite
$B_2$-crystals, which was declared but not clarified at some moments there.
Also we correct some inaccuracies in that paper.

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The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: astro-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: q-fin