Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Curvature properties of Riemannian manifolds with skew-circulant
  structures   We consider a 4-dimensional Riemannian manifold M endowed with a right
skew-circulant tensor structure S, which is an isometry with respect to the
metric g and the fourth power of S is minus identity. We determine a class of
manifolds (M, g, S), whose curvature tensors are invariant under S. For such
manifolds we obtain properties of the Ricci tensor. Also we get expressions of
the sectional curvatures of some special 2-planes in a tangent space of (M, g,
S).

31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an