Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exceptional Points, Nonnormal Matrices, Hierarchy of Spin Matrices and
  an Eigenvalue Problem   Exceptional points of a class of non-hermitian Hamilton operators $\hat H$ of
the form $\hat H=\hat H_0+i\hat H_1$ are studied, where $\hat H_0$ and $\hat
H_1$ are hermitian operators. Finite dimensional Hilbert spaces are considered.
The linear operators $\hat H_0$ and $\hat H_1$ are given by spin matrices for
spin $s=1/2,1,3/2,\dots$. Since the linear operators studied are nonnormal,
properties of such operators are described.

17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
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The categories of this paper are: eess
21
The categories of this paper are: adap-org