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.

Binding-blocking automata

Abstract: We propose an automaton model called as binding-blocking automaton BBA. It is a finite state automaton together with the ability to block some symbols and postpone them for reading by the head at a later time. The idea of blocking some symbols from being read by the head and unblocking when the system requires to read is motivated by peptide computing where some parts of peptide sequences are blocked by attaching an antibody with higher affinity and unblocked at a later point by the removal of the appropriate antibody. We study the variants of such systems, analyse the power of each variants and show various hierarchy results involving them. We also define normal-forms of binding-blocking automata for one of its variants and also show that the acceptance power of this variant of BBA is strictly less than that of multi-head finite automata.

On the equivalence-checking problem for a model of programs related with multi-tape automata

Abstract: We study the equivalence-checking problem for a formal model of computer programs which is used for the purpose of verification. In this model programs are viewed as deterministic finite automata operating on Kripke structures defined in the framework of dynamic logics. When a transition relation in such structures is functional and weakly directed, the result of a program execution does not depend on the order in which basic statements are applied to data states. The models of programs with commuting statements have a close relationship to multi-tape finite automata. We consider the case when evaluation functions which specify truth-values of basic predicates in programs are monotonic. This corresponds to multi-tape automata operating on binary words of the type 0*1*. The main theorem states that the equivalence-checking problem in the model of programs with commuting and monotonic statements is decidable in polynomial time.

A Calculus for Team Automata

Abstract: Team automata are a formalism for the component-based specification of reactive, distributed systems. Their main feature is a flexible technique for specifying coordination patterns among systems, thus extending I/O automata. Furthermore, for some patterns the language recognized by a team automaton can be specified via those languages recognized by its components. We introduce a process calculus tailored over team automata. Each automaton is described by a process, such that its associated (fragment of a) labeled transition system is bisimilar to the original automaton. The mapping is moreover denotational, since the operators defined on processes are in a bijective correspondence with a chosen family of coordination patterns and that correspondence is preserved by the mapping. We thus extend to team automata a few classical results on I/O automata and their representation by process calculi. Moreover, besides providing a language for expressing team automata, we widen the family of coordination patterns for which an equational characterization of the language associated to a composite automaton can be provided. The latter result is obtained by providing a set of axioms, in ACP-style, for capturing bisimilarity in our calculus.

New Results Concerning Synchronized Finite Automata

Abstract: We establish a tight hierarchy of two-way synchronized finite automata having only universal states on the number of allowed processes, i.e. L(2SUFA(kproc)) \(\subsetneq\)L(2SUFA(k + 1-proc)), by studying reduction functions made by two-way deterministic finite automata with a one-way write-only output tape. Consequently for every k > 1, L(2SUFA(k-proc)) has a complete set under 2DFA reductions and is not closed under union or intersection. In contrast, we show that the corresponding hierarchy collapses for unary alphabets. Next we study multihead synchronized finite automata having only universal states. We show that ∪ k=1 ∞ L(2SUFA(k-heads)) = ∪ k=1 ∞ L(2UFA(k-heads)) = NLOG, and ∪ k=1 ∞ L(1SUFA(k- heads)) = ∪ k=1 ∞ L(1UFA(k-heads)). As a result, we establish a tight hierarchy on the number of heads of the two-way machines, i.e. L(2SUFA(k-heads)) \(\subsetneq\)L(2SUFA(k+l-heads)), and a weaker hierarchy of the one-way machines, i.e. L(1SUFA(k-heads)) \(\subsetneq\)L(1SUFA(2k + 1heads)).

Finite state automata representing two-dimensional subshifts

Abstract: We employ a two-dimensional automaton defined in [5] to recognize a class of two-dimensional shifts of finite type having the property that every admissable block found within the related local picture language can be extended to a point of the subshift. Here, we show that the automaton accurately represents the image of the represented two-dimensional shift of finite type under a block code. We further show that such automata can be used to check for a certain type of two-dimensional transitivity in the factor language of the corresponding shift space and how this relates to periodicity in the two-dimensional case. The paper closes with a notion of "follower sets" used to reduce the size of the automata representing two-dimensional sofic shifts.