Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Courant-sharp Robin eigenvalues for the square: the case of negative
  Robin parameter   We consider the cases where there is equality in Courant's nodal domain
theorem for the Laplacian with a Robin boundary condition on the square. In our
previous two papers, we treated the cases where the Robin parameter $h>0$ is
large, small respectively. In this paper we investigate the case where $h<0\,$.

18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
3
The categories of this paper are: physics
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The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int