Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hypercomplex structures with Hermitian-Norden metrics on
  four-dimensional Lie algebras   Integrable hypercomplex structures with Hermitian and Norden metrics on Lie
groups of dimension 4 are considered. The corresponding five types of invariant
hypercomplex structures with hyper-Hermitian metric, studied by M.L. Barberis,
are constructed here. The different cases regarding the signature of the basic
pseudo-Riemannian metric are considered.

0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex