Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Symmetries and conservation laws of the generalized Krichever-Novikov
  equation   A computational classification of contact symmetries and higher-order local
symmetries that do not commute with $t,x$, as well as local conserved densities
that are not invariant under $t,x$ is carried out for a generalized version of
the Krichever-Novikov equation. Several new results are obtained. First, the
Krichever-Novikov equation is explicitly shown to have a local conserved
density that contains $t,x$. Second, apart from the dilational point symmetries
known for special cases of the Krichever-Novikov equation and its generalized
version, no other local symmetries with low differential order are found to
contain $t,x$. Third, the basic Hamiltonian structure of the Krichever-Novikov
equation is used to map the local conserved density containing $t,x$ into a
nonlocal symmetry that contains $t,x$. Fourth, a recursion operator is applied
to this nonlocal symmetry to produce a hierarchy of nonlocal symmetries that
have explicit dependence on $t,x$. When the inverse of the Hamiltonian map is
applied to this hierarchy, only trivial conserved densities are obtained.

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The categories of this paper are: astro-ph
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The categories of this paper are: q-alg
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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: econ
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The categories of this paper are: physics
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph