Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System   We present the public version of hi_class (www.hiclass-code.net), an
extension of the Boltzmann code CLASS to a broad ensemble of modifications to
general relativity. In particular, hi_class can calculate predictions for
models based on Horndeski's theory, which is the most general scalar-tensor
theory described by second-order equations of motion and encompasses any
perfect-fluid dark energy, quintessence, Brans-Dicke, $f(R)$ and covariant
Galileon models. hi_class has been thoroughly tested and can be readily used to
understand the impact of alternative theories of gravity on linear structure
formation as well as for cosmological parameter extraction.

13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex