ω-automaton

About: ω-automaton is a research topic. Over the lifetime, 2299 publications have been published within this topic receiving 68468 citations. The topic is also known as: stream automaton & ω-automata.

An Improved Upper Bound for the Finite Delay of Graphs

Abstract: The notion of graphs solvable with finite delay appears in [1] and [4]. In this note the upper bound on finite delay for a graph with N nodes is reduced to the order of 2N2using techniques from finite automata theory.

Hardware Implementations of Finite Automata and Regular Expressions - Extended Abstract.

Abstract: This extended abstract sketches some of the most recent advances in hardware implementations (and surrounding issues) of finite automata and regular expressions.

Embeddings of local automata

Abstract: A local automaton is by definition such that a bounded information about the past and the future is enough to determine the present state. Due to this synchronization property, these automata play an important role for coding purposes. We prove that any irreducible local automaton is contained in a complete one. The proof uses a result from symbolic dynamics due to M. Nasu called the masking lemma. A consequence of this result in the theory of variable length codes is that any locally parsable regular code is included in a maximal one with the same synchronisation delay.

Minimizing generalized büchi automata

Abstract: We consider the problem of minimization of generalized Buchi automata. We extend fair-simulation minimization and delayed-simulation minimization to the case where the Biichi automaton has multiple acceptance conditions. For fair simulation, we show how to efficiently compute the fair-simulation relation while maintaining the structure of the automaton. We then use the fair-simulation relation to merge states and remove transitions. Our fair-simulation algorithm works in time O(mn 3 k 2 ) where m is the number of transitions, n is the number of states, and k is the number of acceptance sets. For delayed simulation, we extend the existing definition to the case of multiple acceptance conditions. We show that our definition can indeed be used for minimization and give an algorithm that computes the delayed-simulation relation. Our delayed-simulation algorithm works in time O(mn 3 k). We implemented the two algorithms and report on experimental results.

Cellular Automata in Cryptographic Random Generators

Abstract: Cryptographic schemes using one-dimensional, three-neighbor cellular automata as a primitive have been put forth since at least 1985. Early results showed good statistical pseudorandomness, and the simplicity of their construction made them a natural candidate for use in cryptographic applications. Since those early days of cellular automata, research in the field of cryptography has developed a set of tools which allow designers to prove a particular scheme to be as hard as solving an instance of a well- studied problem, suggesting a level of security for the scheme. However, little or no literature is available on whether these cellular automata can be proved secure under even generous assumptions. In fact, much of the literature falls short of providing complete, testable schemes to allow such an analysis. In this thesis, we first examine the suitability of cellular automata as a primitive for building cryptographic primitives. In this effort, we focus on pseudorandom bit generation and noninvertibility, the behavioral heart of cryptography. In particular, we focus on cyclic linear and non-linear au- tomata in some of the common configurations to be found in the literature. We examine known attacks against these constructions and, in some cases, improve the results. Finding little evidence of provable security, we then examine whether the desirable properties of cellular automata (i.e. highly parallel, simple construction) can be maintained as the automata are enhanced to provide a foundation for such proofs. This investigation leads us to a new construction of a finite state cellular automaton (FSCA) which is NP-Hard to invert. Finally, we introduce the Chasm pseudorandom generator family built on this construction and provide some initial experimental results using the NIST test suite.