Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Algebraic conditions for the positivity of sectional curvature   We examine algebraic conditions for the sectional positivity of the Riemann
curvature operator. We describe sufficient conditions for dimension $n=4$, and
complete characterization for a dense open subset of the space of operators in
dimension $4$. We also briefly examine higher-dimentional curvature operators.

15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th