Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On I-null Lie algebras   We consider the class of Lie algebras for which the Koszul 3-form is zero,
and prove that it contains all quotients of Borel subalgebras, or of their
nilradicals, of finite dimensional semi-simple Lie algebras. A list of
Kac-Moody types for indecomposable nilpotent Lie algebras of dimension at most
7 is given.

10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph