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Good-for-MDPs and good-for-games automata are two recent classes of nondeterministic automata that reside between general nondeterministic and deterministic automata. Deterministic automata are good-for-games, and good-for-games automata…

Formal Languages and Automata Theory · Computer Science 2023-07-24 Sven Schewe , Qiyi Tang

We present a formal and constructive simulation framework for nondeterministic finite automata (NFAs) using time-shared, depth-unrolled feedforward networks (TS-FFNs), i.e., acyclic unrolled computations with shared parameters that are…

Machine Learning · Computer Science 2025-10-13 Sahil Rajesh Dhayalkar

Unambiguous B\"uchi automata, i.e. B\"uchi automata allowing only one accepting run per word, are a useful restriction of B\"uchi automata that is well-suited for probabilistic model-checking. In this paper we propose a more permissive…

Formal Languages and Automata Theory · Computer Science 2018-09-26 Christof Löding , Anton Pirogov

We study the emptiness and $\lambda$-reachability problems for unary and binary Probabilistic Finite Automata (PFA) and characterise the complexity of these problems in terms of the degree of ambiguity of the automaton and the size of its…

Formal Languages and Automata Theory · Computer Science 2024-02-14 Paul C. Bell , Pavel Semukhin

Deterministic and nondeterministic finite automata (DFAs and NFAs) are abstract models of computation commonly taught in introductory computing theory courses. These models have important applications (such as fast regular expression…

Computers and Society · Computer Science 2024-05-06 Eliot Wong Robson , Sam Ruggerio , Jeff Erickson

An automaton is history-deterministic if its nondeterminism can be resolved on the fly, only using the prefix of the word read so far. This mild form of nondeterminism has attracted particular attention for its applications in synthesis…

Formal Languages and Automata Theory · Computer Science 2026-05-28 Udi Boker , Thomas A. Henzinger , Karoliina Lehtinen , Keya Prakash

Every language recognized by a non-deterministic finite automaton can be recognized by a deterministic automaton, at the cost of a potential increase of the number of states, which in the worst case can go from $n$ states to $2^n$ states.…

Formal Languages and Automata Theory · Computer Science 2025-02-05 Arnaud Carayol , Philippe Duchon , Florent Koechlin , Cyril Nicaud

We study explorability, a measure of nondeterminism in pushdown automata, which generalises history-determinism. An automaton is k-explorable if, while reading the input, it suffices to follow k concurrent runs, built step-by-step based…

Formal Languages and Automata Theory · Computer Science 2025-11-07 Ayaan Bedi , Karoliina Lehtinen

We define a quantum computational model over infinite words, called Measure-Many Quantum B\"uchi Automata (MMQBA), which extends Measure-many Quantum Finite automata (MMQFA) to the infinite word setting with B\"uchi acceptance condition. In…

Formal Languages and Automata Theory · Computer Science 2026-05-11 Abhisek Midya , A Baskar

We answer two open questions by (Gruber, Holzer, Kutrib, 2009) on the state-complexity of representing sub- or superword closures of context-free grammars (CFGs): (1) We prove a (tight) upper bound of $2^{\mathcal{O}(n)}$ on the size of…

Formal Languages and Automata Theory · Computer Science 2014-10-24 Georg Bachmeier , Michael Luttenberger , Maximilian Schlund

We prove that two-way probabilistic and quantum finite automata (2PFA's and 2QFA's) can be considerably more concise than both their one-way versions (1PFA's and 1QFA's), and two-way nondeterministic finite automata (2NFA's). For this…

Computational Complexity · Computer Science 2014-01-29 Abuzer Yakaryilmaz , A. C. Cem Say

Finite-state tree automata are a well studied formalism for representing term languages. This paper studies the problem of determining the regularity of the set of instances of a finite set of terms with variables, where each variable is…

Symbolic Computation · Computer Science 2009-11-20 Omer Giménez , Guillem Godoy , Sebastian Maneth

We study three levels in a hierarchy of nondeterminism: A nondeterministic automaton $\mathcal{A}$ is determinizable by pruning (DBP) if we can obtain a deterministic automaton equivalent to $\mathcal{A}$ by removing some of its…

Formal Languages and Automata Theory · Computer Science 2025-10-29 Bader Abu Radi , Orna Kupferman , Ofer Leshkowitz

We study alternating automata with qualitative semantics over infinite binary trees: alternation means that two opposing players construct a decoration of the input tree called a run, and the qualitative semantics says that a run of the…

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

We investigate the descriptional complexity of different variants of 1-limited automata (1-las), an extension of two-way finite automata (2nfas) characterizing regular languages. In particular, we consider 2nfas with common-guess…

Formal Languages and Automata Theory · Computer Science 2025-05-01 Bruno Guillon , Luca Prigioniero , Javad Taheri

The bandwidth of a timed language characterizes the quantity of information per time unit (with a finite observation precision $\varepsilon$). Obese timed automata have an unbounded frequency of events and produce information at the maximal…

Formal Languages and Automata Theory · Computer Science 2025-08-26 Eugene Asarin , Aldric Degorre , Catalin Dima , Bernardo Jacobo Inclán

We follow a connection between tight determinisation and complementation and establish a complementation procedure from parity automata to nondeterministic B\"uchi automata and prove it to be tight up to an $O(n)$ factor, where $n$ is the…

Formal Languages and Automata Theory · Computer Science 2014-09-12 Sven Schewe , Thomas Varghese

Quantitative languages are an extension of boolean languages that assign to each word a real number. Mean-payoff automata are finite automata with numerical weights on transitions that assign to each infinite path the long-run average of…

Logic in Computer Science · Computer Science 2015-05-19 Krishnendu Chatterjee , Laurent Doyen , Herbert Edelsbrunner , Thomas A. Henzinger , Philippe Rannou

We discuss the problem of learning a deterministic finite automaton (DFA) from a confidence oracle. That is, we are given access to an oracle $Q$ with incomplete knowledge of some target language $L$ over an alphabet $\Sigma$; the oracle…

Formal Languages and Automata Theory · Computer Science 2023-11-21 Wilson Wu