Shrinking Alternating Two-Pushdown Automata

Friedrich OTTO  Etsuro MORIYA  

IEICE TRANSACTIONS on Information and Systems   Vol.E87-D   No.4   pp.959-966
Publication Date: 2004/04/01
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Automata and Formal Language Theory
shrinking,  alternating,  two-pushdown automaton,  PSPACE-complete,  

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The alternating variant of the shrinking two-pushdown automaton of Buntrock and Otto (1998) is introduced. It is shown that the class of languages accepted by these automata is contained in the class of deterministic context-sensitive languages, and that it contains a PSPACE-complete language. Hence, the closure of this class of languages under log-space reductions coincides with the complexity class PSPACE.