Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On approximate Birkhoff-James orthogonality and normal cones in a normed
  space   We study two notions of approximate Birkhoff-James orthogonality in a normed
space, from a geometric point of view, and characterize them in terms of normal
cones. We further explore the interconnection between normal cones and
approximate Birkhoff-James orthogonality to obtain a complete characterization
of normal cones in a two-dimensional smooth Banach space. We also obtain a
uniqueness theorem for approximate Birkhoff-James orthogonality set in a normed
space.

33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con