Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Short Decidability Proof for DPDA Language Equivalence via First-Order
  Grammars   The main aim of the paper is to give a short self-contained proof of the
decidability of language equivalence for deterministic pushdown automata, which
is the famous problem solved by G. Senizergues, for which C. Stirling has
derived a primitive recursive complexity upper bound. The proof here is given
in the framework of first-order grammars, which seems to be particularly apt
for the aim. An appendix presents a modification of Stirling's approach,
yielding a complexity bound of the form tetr(2,g(n)) where tetr is the
(nonelementary) operator of iterated exponentiation (tetration) and g is an
elementary function of the input size.

3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat