Showing papers on "Deterministic pushdown automaton published in 1983"
TL;DR: Topdown pushdown tree automata are defined and shown to be equivalent to restricted PDTA's, whose stack is linear: this both yields a more operational way of recognizing context-free tree languages and connects them with the class of indexed languages.
Abstract: We define topdown pushdown tree automata (PDTA's) which extend the usual string pushdown automata by allowing trees instead of strings in both the input and the stack. We prove that PDTA's recognize the class of context-free tree languages. (Quasi)realtime and deterministic PDTA's accept the classes of Greibach and deterministic tree languages, respectively. Finally, PDTA's are shown to be equivalent to restricted PDTA's, whose stack is linear: this both yields a more operational way of recognizing context-free tree languages and connects them with the class of indexed languages.
82 citations
01 Dec 1983
TL;DR: It is shown that alternation corresponds to one more iteration of pushdowns, and nondeterministic 2-way and multi-head iterated pushdown automata characterize deterministic iterated exponential time complexity classes.
Abstract: An iterated pushdown is a pushdown of pushdowns of ... of pushdowns. An iterated exponential function is 2 to the 2 to the ... to the 2 to some polynomial. The main result is that nondeterministic 2-way and multi-head iterated pushdown automata characterize deterministic iterated exponential time complexity classes. This is proved by investigating both nondeterministic and alternating auxiliary iterated pushdown automata, for which similar characterization results are given. In particular it is shown that alternation corresponds to one more iteration of pushdowns. These results are applied to the 1-way iterated pushdown automata: (1) they form a proper hierarchy with respect to the number of iterations, (2) their emptiness problem is complete in deterministic iterated exponential time.
64 citations
TL;DR: It is proved that the set of all languages accepted within a fixed, language dependent number of steps by deterministic one dimensional cellular acceptors is a proper subset of theSet of all regular languages.
Abstract: It is proved that the set of all languages accepted within a fixed, language dependent number of steps by deterministic one dimensional cellular acceptors is a proper subset of the set of all regular languages.
31 citations
TL;DR: It is shown that k + 1 heads are better than k for one-way multihead pushdown (resp. stack) automata if they do not have endmarkers on the input tape and accept by final state with at least one input head at the right end of the input string.
10 citations
9 citations
TL;DR: An algorithm simulating 2dpda(k)‘s in O(r) time and space, where r is the number of reachable surface configurations, is designed, to obtain a similar result for two-way nondeterministic pushdown automata.
5 citations
09 Mar 1983
TL;DR: This paper is devoted to the study of languages satisfying the prefixity property and of those that are the star of the previous ones.
Abstract: This paper is devoted to the study of languages satisfying the prefixity property and of those that are the star of the previous ones.
3 citations
TL;DR: It seems that there are subclasses of pushdown acceptors which have a decidable ambiguity problem but an undecidable inherent ambiguity problem, and these classes are the first known to exhibit this property.
3 citations
TL;DR: The family of stack uniform strict deterministic languages can be characterized by a grammar family because the grammar is required to be in a special form, but the construction is more natural than previously known constructions.
1 citations