Pushdown automaton

About: Pushdown automaton is a research topic. Over the lifetime, 1868 publications have been published within this topic receiving 35399 citations.

Serializing the Parallelism in Parallel Communicating Pushdown Automata Systems

Abstract: We consider parallel communicating pushdown automata systems (PCPA) and define a property called known communication for it. We use this property to prove that the power of a variant of PCPA, called returning centralized parallel communicating pushdown automata (RCPCPA), is equivalent to that of multi-head pushdown automata. The above result presents a new sub-class of returning parallel communicating pushdown automata systems (RPCPA) called simple-RPCPA and we show that it can be written as a finite intersection of multi-head pushdown automata systems.

Using adaptive formalisms to describe context-dependencies in natural language

Abstract: This text sketches a method based on adaptive technology for representing context-dependencies in NL processing. Based on a previous work [4] dedicated to syntactical ambiguities and nondeterminisms in NL handling we extend it to consider context-dependencies not previously addressed. Although based on the powerful adaptive formalism [3], our method relies on adaptive structured pushdown automata [1] and grammars [2] - resulting simplicity, low-cost and efficiency.

Direct construction of finite state machines

Abstract: A method and system for direct construction of a minimal deterministic finite state machine corresponding to a regular expression are provided. The method includes providing a regular expression represented as a regular expression tree with nodes of operators and leaves of elementary character transitions and traversing the regular expression tree recursively to build minimal finite state automata (FSAs) corresponding to the branches of the tree, wherein the FSAs end in a specified tail automaton. The operators are concatenation, alternation, and Kleene closure. A concatenation operation is performed by recursive construction in reverse order wherein each automaton built becomes the tail for the preceding argument of the operation. An alternation operation is performed by recursively building automata corresponding to the arguments of the operation with the same tail and merging them. A Kleene closure operation is performed by: building an automaton terminating in a unique marker; merging the automaton with the tail automaton to form a combined automaton; and traversing the combined automaton to expand the marker into transitions and states to achieve the intended behaviour.

Teaching push-down automata and turing machines

Abstract: In this paper we present the new version of a tool to assist in teaching formal languages and automata theory. In the previous version the tool provided algorithms for regular expressions, finite automata and context free grammars. The new version can simulate as well push-down automata and Turing machines.