Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A General Backwards Calculus of Variations via Duality   We prove Euler-Lagrange and natural boundary necessary optimality conditions
for problems of the calculus of variations which are given by a composition of
nabla integrals on an arbitrary time scale. As an application, we get
optimality conditions for the product and the quotient of nabla variational
functionals.

3
The categories of this paper are: physics
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The categories of this paper are: cond-mat
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The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
28
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: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: nlin