Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A remark on natural constraints in variational methods and an
  application to superlinear Schr\"odinger systems   For a regular functional J defined on a Hilbert space X, we consider the set
N of points x of X such that the projection of the gradient of J at x onto a
closed linear subspace V(x) of X vanishes. We study sufficient conditions for a
constrained critical point of J restricted to N to be a free critical point of
J, providing a unified approach to different natural constraints known in the
literature, such as the Birkhoff-Hestenes natural isoperimetric conditions and
the Nehari manifold. As an application, we prove multiplicity of solutions to a
class of superlinear Schr\"odinger systems on singularly perturbed domains.

15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat