Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lines of Curvature on Quadric Hypersurfaces of $ \mathbb{R}^4$   Here are described the geometric structures of the lines of principal
curvature and the partially umbilic singularities of the tridimensional non
compact generic quadric hypersurfaces of ${\mathbb R}^4$. This includes the
ellipsoidal hyperboloids of one and two sheets and the toroidal hyperboloids.
The present study complements the analysis of the compact ellipsoidal
hypersurfaces carried out by D. Lopes, R. Garcia and J. Sotomayor.

6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th