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.

What's decidable about recursive hybrid automata?

Abstract: Recursive hybrid automata generalize recursive state machines in a similar way as hybrid automata generalize state machines. Recursive hybrid automata can be considered as collection of classical hybrid automata with special states that correspond to potentially recursive invocation of hybrid automata from the collection. During each such invocation, the semantics of recursive hybrid automata permits optional passing of the continuous variables using either pass-by-value or pass-by-reference mechanism. This model generalizes recursive timed automata model introduced by Trivedi and Wojtczak and dense-timed pushdown automata by Abdulla, Atig, and Stenman. We study natural reachability problem for recursive hybrid automata. Given the undecidability of this problem for hybrid automata, it is not surprising that the problem remains undecidable without further restrictions. We consider various restrictions of recursive hybrid automata and characterize the boundaries between decidable and undecidable variants.

Is there a best büchi automaton for explicit model checking

Abstract: LTL to Buchi automata (BA) translators are traditionally optimized to produce automata with a small number of states or a small number of non-deterministic states. In this paper, we search for properties of Buchi automata that really influence the performance of explicit model checkers. We do that by manual analysis of several automata and by experiments with common LTL-to-BA translators and realistic verification tasks. As a result of these experiences, we gain a better insight into the characteristics of automata that work well with Spin.

Minimisation of Multiplicity Tree Automata.

Abstract: We consider the problem of minimising the number of states in a multiplicity tree automaton over the field of rational numbers. We give a minimisation algorithm that runs in polynomial time assuming unit-cost arithmetic. We also show that a polynomial bound in the standard Turing model would require a breakthrough in the complexity of polynomial identity testing by proving that the latter problem is logspace equivalent to the decision version of minimisation. The developed techniques also improve the state of the art in multiplicity word automata: we give an NC algorithm for minimising multiplicity word automata. Finally, we consider the minimal consistency problem: does there exist an automaton with $n$ states that is consistent with a given finite sample of weight-labelled words or trees? We show that this decision problem is complete for the existential theory of the rationals, both for words and for trees of a fixed alphabet rank.

Edit Automata: Enforcement Mechanisms for

Abstract: We analyze the space of security policies that can be enforced by monitoring and modifying programs at run time. Our program monitors, called edit automata, are abstract machines that examine the sequence of application program actions and transform the sequence when it deviates from a specied policy. Edit automata have a rich set of transformational powers: They may terminate the application, thereby truncating the program action stream; they may suppress undesired or dangerous actions without necessarily terminating the program; and they may also insert additional actions into the event stream. After providing a formal denition of edit automata, we develop a rigorous framework for reasoning about them and their cousins: truncation automata (which can only terminate applications), suppression automata (which can terminate applications and suppress individual actions), and insertion automata (which can terminate and insert). We give a settheoretic characterization of the policies each sort of automaton can enforce and we provide examples of policies that can be enforced by one sort of automaton but not another.

An introduction to finite automata and their connection to logic

Abstract: This is a tutorial on finite automata. We present the standard material on determinization and minimization, as well as an account of the equivalence of finite automata and monadic second-order logic. We conclude with an introduction to the syntactic monoid, and as an application give a proof of the equivalence of first-order definability and aperiodicity.