Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Negative Times of the Davey-Stewartson Integrable Hierarchy   We use example of the Davey-Stewartson hierarchy to show that in addition to
the standard equations given by Lax operator and evolutions of times with
positive numbers, one can consider time evolutions with negative numbers and
the same Lax operator. We derive corresponding Lax pairs and integrable
equations.

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The categories of this paper are: hep-ph
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The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: cs
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The categories of this paper are: acc-phys