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Minimal deterministic finite automata (DFAs) can be reduced further at the expense of a finite number of errors. Recently, such minimization algorithms have been improved to run in time O(n log n), where n is the number of states of the…

Formal Languages and Automata Theory · Computer Science 2015-05-27 Andreas Maletti , Daniel Quernheim

String analysis is the problem of reasoning about how strings are manipulated by a program. It has numerous applications including automatic detection of cross-site scripting (XSS). A popular string analysis technique includes symbolic…

Logic in Computer Science · Computer Science 2020-11-02 Lukas Holik , Petr Janku , Anthony W. Lin , Philipp Rümmer , Tomas Vojnar

Complementation of finite automata is a basic operation used in numerous applications. The standard way to complement a nondeterministic finite automaton (NFA) is to transform it into an equivalent deterministic finite automaton (DFA) and…

Formal Languages and Automata Theory · Computer Science 2025-07-16 Lukáš Holík , Ondřej Lengál , Juraj Major , Adéla Štěpková , Jan Strejček

A goal of this paper is to introduce the new construction of an automaton with shortest synchronizing word of length $O(d^{\frac{n}{d}})$, where $d \in \mathbb{N}$ and $n$ is the number of states for that automaton. Additionally we…

Formal Languages and Automata Theory · Computer Science 2020-06-23 Jakub Ruszil

Given an order of the underlying alphabet we can lift it to the states of a finite deterministic automaton: to compare states we use the order of the strings reaching them. When the order on strings is the co-lexicographic one \emph{and}…

Formal Languages and Automata Theory · Computer Science 2022-03-24 Giovanna D'Agostino , Davide Martincigh , Alberto Policriti

We study extremal and algorithmic questions of subset and careful synchronization in monotonic automata. We show that several synchronization problems that are hard in general automata can be solved in polynomial time in monotonic automata,…

Formal Languages and Automata Theory · Computer Science 2017-11-27 Andrew Ryzhikov , Anton Shemyakov

It was shown before that the NP-hard problem of deterministic finite automata (DFA) identification can be effectively translated to Boolean satisfiability (SAT). Modern SAT-solvers can tackle hard DFA identification instances efficiently.…

Formal Languages and Automata Theory · Computer Science 2016-02-22 Vladimir Ulyantsev , Ilya Zakirzyanov , Anatoly Shalyto

The work presents some new algorithms realized recently in the package TESTAS. They decide whether or not deterministic finite automaton (DFA) is synchronizing, several procedures find relatively short synchronizing words and a…

Formal Languages and Automata Theory · Computer Science 2020-11-12 Avraham N. Trahtman

We address the problem of performing semantic transformations on strings, which may represent a variety of data types (or their combination) such as a column in a relational table, time, date, currency, etc. Unlike syntactic…

Databases · Computer Science 2012-04-30 Rishabh Singh , Sumit Gulwani

Several new algorithms for deciding emptiness of Boolean combinations of regular languages and of languages of alternating automata (AFA) have been proposed recently, especially in the context of analysing regular expressions and in string…

Formal Languages and Automata Theory · Computer Science 2023-04-12 Tomáš Fiedor , Lukáš Holík , Martin Hruška , Adam Rogalewicz , Juraj Síč , Pavol Vargovčík

Modern language models define distributions over strings, but downstream tasks often require different output formats. For instance, a model that generates byte-pair strings does not directly produce word-level predictions, and a DNA model…

Computation and Language · Computer Science 2026-03-09 Vésteinn Snæbjarnarson , Samuel Kiegeland , Tianyu Liu , Reda Boumasmoud , Ryan Cotterell , Tim Vieira

In this paper, a compressed membership problem for finite automata, both deterministic and non-deterministic, with compressed transition labels is studied. The compression is represented by straight-line programs (SLPs), i.e. context-free…

Formal Languages and Automata Theory · Computer Science 2013-10-28 Artur Jeż

It was conjectured by \v{C}ern\'y in 1964, that a synchronizing DFA on $n$ states always has a shortest synchronizing word of length at most $(n-1)^2$, and he gave a sequence of DFAs for which this bound is reached. Until now a full…

Combinatorics · Mathematics 2017-06-19 Michiel de Bondt , Henk Don , Hans Zantema

We present an efficient algorithm for checking language equivalence of states in top-down deterministic finite tree automata (DFTAs). Unlike string automata, tree automata operate over hierarchical structures, posing unique challenges for…

Formal Languages and Automata Theory · Computer Science 2025-04-08 Zhibo Deng , Vladimir A. Zakharov

An index for a finite automaton is a powerful data structure that supports locating paths labeled with a query pattern, thus solving pattern matching on the underlying regular language. In this paper, we solve the long-standing problem of…

Data Structures and Algorithms · Computer Science 2020-07-16 Nicola Cotumaccio , Nicola Prezza

In reactive synthesis, the goal is to automatically generate an implementation from a specification of the reactive and non-terminating input/output behaviours of a system. Specifications are usually modelled as logical formulae or automata…

Formal Languages and Automata Theory · Computer Science 2023-06-22 Léo Exibard , Emmanuel Filiot , Pierre-Alain Reynier

A deterministic finite automaton (DFA) is composite if its language can be decomposed into an intersection of languages of smaller DFAs. Otherwise, A is prime. This notion of primality was introduced by Kupferman and Mosheiff in 2013, and…

Formal Languages and Automata Theory · Computer Science 2021-07-13 Ismaël Jecker , Nicolas Mazzocchi , Petra Wolf

Nondeterministic automata may be viewed as succinct programs implementing deterministic automata, i.e. complete specifications. Converting a given deterministic automaton into a small nondeterministic one is known to be computationally very…

Formal Languages and Automata Theory · Computer Science 2021-07-12 Robert Samuel Ralph Myers , Henning Urbat

In general, the representation of combinatorial objects is decisive for the feasibility of several enumerative tasks. In this work, we show how a (unique) string representation for (complete) initially-connected deterministic automata…

Formal Languages and Automata Theory · Computer Science 2009-06-23 Marco Almeida , Nelma Moreira , Rogério Reis

Reactive synthesis from Linear Temporal Logic over finite traces (LTLf) can be reduced to a two-player game over a Deterministic Finite Automaton (DFA) of the LTLf specification. The primary challenge here is DFA construction, which is…

Artificial Intelligence · Computer Science 2025-08-25 Yongkang Li , Shengping Xiao , Shufang Zhu , Jianwen Li , Geguang Pu