Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Proceedings of the 9th International Workshop on Verification and
  Program Transformation   The previous VPT 2020 workshop was organized in honour of Professor Alberto
Pettorossi on the occasion of his academic retirement from Universit\`a di Roma
Tor Vergata. Due to the pandemic the VPT 2020 meeting was cancelled but its
proceeding have already appeared in the EPTCS 320 volume. The joint VPT-20-21
event has subsumed the original programme of VPT 2020 and provided an
opportunity to meet and celebrate the achievements of Professor Alberto
Pettorossi; its programme was further expanded with the newly submitted
presentations for VPT 2021. The aim of the VPT workshop series is to provide a
forum where people from the areas of program transformation and program
verification can fruitfully exchange ideas and gain a deeper understanding of
the interactions between those two fields.

6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ