Topic
Pushdown automaton
About: Pushdown automaton is a research topic. Over the lifetime, 1868 publications have been published within this topic receiving 35399 citations.
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01 Jan 2013
TL;DR: In this paper, the authors describe the program LALBLC which tests whether two determin-istic pushdown automata recognize the same language, i.e., English.
Abstract: We describe the program LALBLC which tests whether two determin- istic pushdown automata recognize the same language.
7 citations
27 Aug 2013
TL;DR: The notion of partially commutative context-free grammars is used to describe a new class of asynchronously communicating pushdown systems with a mild shape constraint on the stacks for which the program-point coverability problem remains decidable.
Abstract: In this paper, we study the program-point reachability problem of concurrent pushdown systems that communicate via unbounded and unordered message buffers. Our goal is to relax the common restriction that messages can only be retrieved by a pushdown process when its stack is empty. We use the notion of partially commutative context-free grammars to describe a new class of asynchronously communicating pushdown systems with a mild shape constraint on the stacks for which the program-point coverability problem remains decidable. Stacks that fit the shape constraint may reach arbitrary heights; further a process may execute any communication action (be it process creation, message send or retrieval) whether or not its stack is empty. This class extends previous computational models studied in the context of asynchronous programs, and enables the safety verification of a large class of message passing programs.
7 citations
Journal Article•
TL;DR: It is proved that all these systems accept the family of recursively enumerable languages both in the centralized and in the non-centralized strategies and in both returning and non-returning communication modes with only two components.
Abstract: We consider automata systems consisting of several pushdown automata working in parallel and communicating the contents of their stacks by request. We show that centralized non-returning parallel communicating pushdown automata systems with three components recognize all recursively enumerable languages. We also show that centralized returning pushdown automata systems accept non-ET0L languages. We study two variants of communication: one uses filters in communication and in the other only specified number of symbols are communicated. We prove that all these systems accept the family of recursively enumerable languages both in the centralized and in the non-centralized strategies and in both returning and non-returning communication modes with only two components.
7 citations
7 citations
16 Jul 2006
TL;DR: It is shown that any logarithmic space, polynomial time two-sided bounded-error probabilistic auxiliary pushdown automaton (the corresponding complexity class is denoted by BPHLOGCFL) can be simulated by an SC2 machine.
Abstract: We extend Nisan's breakthrough derandomization result that BP/sub H/L /spl sube/ SC/sup 2/ (1992) to bounded error probabilistic complexity classes based on auxiliary pushdown automata. In particular, we show that any logarithmic space, polynomial time two-sided bounded-error probabilistic auxiliary pushdown automaton (the corresponding complexity class is denoted by BP/sub H/LOGCFL) can be simulated by an SC/sup 2/ machine. This derandomization result improves a classical result by Cook (1979) that LOGDCFL /spl sube/ SC/sup 2/ since LOGDCFL is contained in BP/sub H/LOGCFL. We also present a simple circuit-based proof that BP/sub H/LOGCFL is in NC/sup 2/.
7 citations