Alternating and Empty Alternating Auxiliary Stack Automata
نویسندگان
چکیده
We consider variants of alternating auxiliary stack automata and characterize their computational power when the number of alternations is bounded by a constant or unlimited. In this way we get new characterizations of NP, the polynomial hierarchy, PSpace, and bounded query classes like co-DP=NL〈NP[1]〉 and 2P=P , in a uniform framework. c © 2002 Elsevier Science B.V. All rights reserved.
منابع مشابه
Alternating Regular Tree Grammars in the Framework of Lattice-Valued Logic
In this paper, two different ways of introducing alternation for lattice-valued (referred to as {L}valued) regular tree grammars and {L}valued top-down tree automata are compared. One is the way which defines the alternating regular tree grammar, i.e., alternation is governed by the non-terminals of the grammar and the other is the way which combines state with alternation. The first way is ta...
متن کاملEmptiness of Multi-pushdown Automata Is 2ETIME-Complete
Abstract. We consider multi-pushdown automata, a multi-stack extension of pushdown automata that comes with a constraint on stack operations: a pop can only be performed on the first non-empty stack (which implies that we assume a linear ordering on the collection of stacks). We show that the emptiness problem for multi-pushdown automata is 2ETIME-complete wrt. the number of stacks. Containment...
متن کاملProperties of Probabilistic Pushdown Automata
Properties of probabilistic as well as \probabilistic plus nondeterministic" pushdown automata and auxiliary pushdown automata are studied. These models are analogous to their counterparts with nondeterministic and alternating states. Complete characterizations in terms of well-known complexity classes are given for the classes of languages recognized by polynomial time-bounded, logarithmic spa...
متن کاملCounting and empty alternating pushdown automata
We show that the class of context free languages CFL is not equal to ⊕1−PDA (= ⊕CFL), the class of languages, which are recognized by a nondeterministic oneway push-down automaton equipped with parity acceptance. Furthermore we show that LOG(⊕CFL) = ⊕AuxPDApt contains all languages, which can be recognized by a uniform weak unambiguous AC1-circuit introduced in [LR90a]. Therefore, it contains a...
متن کاملConjunctive Grammars and Alternating Pushdown Automata Draft Paper
In this paper we introduce a variant of alternating pushdown automata, Synchronized Alternating Pushdown Automata, which accept the same class of languages as those generated by conjunctive grammars.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Theor. Comput. Sci.
دوره 299 شماره
صفحات -
تاریخ انتشار 2000