Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Grad-Rubin boundary value problem for the two-dimensional
  magneto-hydrostatic equations   In this work, we study the solvability of a boundary value problem for the
magneto-hydrostatic equations originally proposed by Grad and Rubin in the late
50's. The proof relies on a fixed point argument which combines the so-called
current transport method together with H\"older estimates for a class of
non-convolution singular integral operators. The same method allows to solve an
analogous boundary value problem for the steady incompressible Euler equations.

5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th