Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SETI in 2020   In the spirit of Trimble's "Astrophysics in XXXX' series, I very briefly and
subjectively review developments in SETI in 2020. My primary focus is 75 papers
and books published or made public in 2020, which I sort into six broad
categories: results from actual searches, new search methods and
instrumentation, target and frequency seleciton, the development of
technosignatures, theory of ETIs, and social aspects of SETI.

17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc