Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Recursion operators for a class of integrable third-order evolution
  equations   We consider $u_t=u^{\alpha} u_{xxx}+n(u)u_xu_{xx}+m(u)u_x^3+ r(u)u_{xx}
+p(u)u_x^2 + q(u)u_x+s(u)$ with $\alpha=0$ and $\alpha=3$, for those functional
forms of $m, n, p, q, r, s$ for which the equation is integrable in the sense
of an infinite number of Lie-B\"acklund symmetries. Local $x$- and
$t$-independent recursion operators that generate these infinite sets of
symmetries are obtained for the equations. A combination of potential forms,
hodograph transformations and $x$-generalised hodograph transformations are
applied to the obtained equations.

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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: solv-int
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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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: hep-ph
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex