Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Euler-Lagrange equations for composition functionals in calculus of
  variations on time scales   In this paper we consider the problem of the calculus of variations for a
functional which is the composition of a certain scalar function $H$ with the
delta integral of a vector valued field $f$, i.e., of the form
$H(\int_{a}^{b}f(t,x^{\sigma}(t),x^{\Delta}(t))\Delta t)$. Euler-Lagrange
equations, natural boundary conditions for such problems as well as a necessary
optimality condition for isoperimetric problems, on a general time scale, are
given. A number of corollaries are obtained, and several examples illustrating
the new results are discussed in detail.

36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat