Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hirota bilinear forms of the AKNS($N$) systems   We study the AKNS($N$) hierarchy for $N=3,4,5,6$. We give the Hirota bilinear
forms of these systems and present local and nonlocal reductions of them. We
give the Hirota bilinear forms of the reduced equations. The compatibility of
the commutativity diagrams of the application of the recursion operator,
reductions of the AKNS($N$) systems, and Hirota bilinearization is also
studied.

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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: astro-ph