We consider the problem of reducing the number of states of nondeterministic finite automata, and show how to encode the reduction as a Boolean satisfiability problem. This approach improves on previous work by reducing a more general class of automata. Experimental results show that it produces a minimal automaton in almost all cases and that the running time compares favourably to the Kameda-...

A finite automaton is said to be directable if it has an input word, a directing word, which takes it from every state into the same state. For nondeterministic (n.d.) automata, directability can be generalized in several ways, three such notions, D1-, D2-, and D3-directability, are used. In this paper, we consider monogenic n.d. automata, and for each i = 1, 2, 3, we present sharp bounds for t...

A model of nondeterministic nite automaton over ((nite) partial orders is introduced. It captures existential monadic second-order logic in expressive power and generalizes classical word automata and tree automata. Special forms, such as deterministic automata, are discussed, and logical and algorithmic properties are analyzed, like closure under complement and decid-ability of the nonemptines...

This paper addresses the problem of generating deterministic ω-automata for formulas of linear temporal logic, which can be solved by applying wellknown algorithms to construct a nondeterministic Büchi automaton for the given formula on which we then apply a determinization algorithm. We study here in detail Safra’s determinization algorithm, present several heuristics that attempt to decrease ...

We describe an algorithm that, given as input a nondeterministic finite automaton A of size n, decides in O(n2) time whether the language accepted by A is a code. Let Σ be a finite alphabet. A language η ⊆ Σ∗ is a code if every string in η∗ is written uniquely as a concatenation of strings from η, or, equivalently, if η∗ is a free submonoid of Σ∗ and η is its minimal generating set.

The main idea of this paper is to show some important differences between graph grammars and hypergraph grammars in context of freeness. On the other hand, we give a possibility to transform the planar structure of a hypergraph into a linear one with concern of determinism. This can create a path to transform a pushdown automaton into a generative grammar equivalent. Key-Words: Hyperedge Replac...

Automata we have seen so far are deterministic, which means that for every input exactly one transition is available from the current state. Now we will present nondeterministic automata, where several transitions may be possible. In a deterministic automaton for any state and any transition only one successor is available. More formally, if Q is the set of states and Σ is the alphabet of trans...

The paper presents several illustrations of concept of subsystem when applying various types of mappings. There are specifications of notions as input-output system in a certain period of time, stage of system at a given moment, characterization of deterministic, nondeterministic and stochastic system and reasoning over their properties. In the end there are shown some applications of presented...

FAS'rUS is a (slightly permuted) acronym for Finite State Automaton Text Understanding System. It is a. system [br extracting information fi'om free text in English (Japanese is under development), for entry into a database, and potentially for other apl)lications. It works essentially as a set of cascaded, nondeterministic finite state automata . FASTUS is rnost appropriate for inform.ation e~...

It is proved that every regular expression of size n can be converted into an equivalent nondeterministic nite automaton (NFA) of size O(n(log n) 2) in polynomial time. The best previous conversions result in NFAs of worst case size (n 2). Moreover, the nonexistence of any linear conversion is proved: we give a language Ln described by a regular expression of size O(n) such that every NFA accep...