Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Impossible configurations for geodesics on negatively-curved surfaces   Hass and Scott's example of a 4-valent graph on the 3-punctured sphere that
cannot be realized by geodesics in any metric of negative curvature is
generalized to impossible configurations filling surfaces of genus $n$ with $k$
punctures for any $n$ and $k$.

23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
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
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph