Path: utzoo!attcan!uunet!cs.utexas.edu!swrinde!ucsd!ucbvax!wisdom.weizmann.ac.IL!harel
From: harel@wisdom.weizmann.ac.IL (David Harel)
Newsgroups: comp.theory
Subject: stack automata. clarification.
Message-ID: <9007021626.AA06729@irt.watson.ibm.com>
Date: 2 Jul 90 16:26:46 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: David Harel <harel%wisdom.weizmann.ac.il@VM1.NoDak.EDU>
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   Regarding our posting of Jun 25, we would like to clarify the kinds
of automata we are talking about. They are one-way stack automata (in
contrast to the two-way automata defined in Hopcroft and Ullman, p. 381).
In other words, they are pda's that can travel up and down the stack
(but only one-way along the input), looking and contemplating, but making
changes only at the top. Thus, Hopcroft and Ullman have no results
relevant to our results and questions.