Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Regular tree languages in low levels of the Wadge Hierarchy   In this article we provide effective characterisations of regular languages
of infinite trees that belong to the low levels of the Wadge hierarchy. More
precisely we prove decidability for each of the finite levels of the hierarchy;
for the class of the Boolean combinations of open sets $BC(\Sigma_1^0)$ (i.e.
the union of the first $\omega$ levels); and for the Borel class $\Delta_2^0$
(i.e. for the union of the first $\omega_1$ levels).

4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ