Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Matters of Gravity, the newsletter of the APS Topical Group on
  Gravitation, Spring 2001   Contents:
  We hear that... by Jorge Pullin
  * Reflections of a decade:
  Matters of Gravity and the Topical Group in Gravitation, by Beverly Berger
  10 Years in Gravitational Wave Detection, by Peter Saulson
  Ten years of general relativity, some reflections, by Carlo Rovelli
  Tabletop gravity experiments, by Jens Gundlach
  String Theory: the past ten years, by Gary Horowitz
  * Conference reports:
  Fourth Capra Meeting on Radiation Reaction, by Lior Burko
  Workshop on Numerical Relativity, by Michael Koppitz
  Workshop on Canonical & Quantum Gravity III by J. Lewandowski
  and J. Wisniewski

11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex