Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Complexity Results on Register Pushdown Automata   Register pushdown automata (RPDA) is an extension of classical pushdown
automata to handle data values in a restricted way. RPDA attracts attention as
a model of a query language for structured documents with data values. The
membership and emptiness problems for RPDA are known to be EXPTIME-complete.
This paper shows the membership problem becomes PSPACE-complete and NP-complete
for nondecreasing and growing RPDA, respectively, while the emptiness problem
remains EXPTIME-complete for these subclasses.

21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph