Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A multiplicity result for the problem $\delta d \xi = f'(<\xi,\xi>)\xi$   In this paper we consider the nonlinear equation involving differential forms
on a compact Riemannian manifold $\delta d \xi = f'(<\xi,\xi>)\xi$. This
equation is a generalization of the semilinear Maxwell equations recently
introduced in a paper by Benci and Fortunato. We obtain a multiplicity result
both in the positive mass case (i.e. $f'(t)\geq\epsilon>0$ uniformly) and in
the zero mass case ($f'(t)\geq 0$ and $f'(0)=0$) where a strong convexity
hypothesis on the nonlinearity is assumed.

15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
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The categories of this paper are: eess
10
The categories of this paper are: q-bio