Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Canonical description of incompressible fluid -- Dirac brackets approach   We present a novel canonical description of the incompressible fluid
dynamics. This description uses the dynamical constraints, in our case
reflecting "incompressibility" assumption, and leads to replacement of usual
hydrodynamical Poisson brackets for density and velocity fields with Dirac
brackets. The resulting equations are then known nonlinear, and non-local in
space, equations for incompressible fluid velocity.

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The categories of this paper are: mtrl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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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: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph