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We introduce a generalization of Selman's P-selectivity that yields a more flexible notion of selectivity, called (polynomial-time) multi-selectivity, in which the selector is allowed to operate on multiple input strings. Since our…

Computational Complexity · Computer Science 2007-05-23 Lane A. Hemaspaandra , Zhigen Jiang , Joerg Rothe , Osamu Watanabe

In this work, we study the problems of counting and sampling Mazurkiewicz traces that a regular language touches. Fix an alphabet $\Sigma$ and an independence relation $\mathbb{I} \subseteq \Sigma \times \Sigma$. The input consists of a…

Formal Languages and Automata Theory · Computer Science 2025-12-02 Alexis de Colnet , Kuldeep S. Meel , Umang Mathur

In this paper we study lower bounds for the fundamental problem of text indexing with mismatches and differences. In this problem we are given a long string of length $n$, the "text", and the task is to preprocess it into a data structure…

Data Structures and Algorithms · Computer Science 2018-12-24 Vincent Cohen-Addad , Laurent Feuilloley , Tatiana Starikovskaya

The complexity of representing a polynomial by a Read-Once Oblivious Algebraic Branching Program (ROABP) is highly dependent on the chosen variable ordering. Bhargava et al. prove that finding the optimal ordering is NP-hard, and provide…

Computational Complexity · Computer Science 2025-09-17 C. Ramya , Pratik Shastri

We present efficient algorithms to reduce the size of nondeterministic B\"uchi word automata (NBA) and nondeterministic finite word automata (NFA), while retaining their languages. Additionally, we describe methods to solve PSPACE-complete…

Formal Languages and Automata Theory · Computer Science 2023-06-22 Lorenzo Clemente , Richard Mayr

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

Many important combinatorial problems can be modeled as constraint satisfaction problems. Hence identifying polynomial-time solvable classes of constraint satisfaction problems has received a lot of attention. In this paper, we are…

Data Structures and Algorithms · Computer Science 2017-11-15 Martin Grohe , Dániel Marx

We investigate the constrained synchronization problem for weakly acyclic, or partially ordered, input automata. We show that, for input automata of this type, the problem is always in NP. Furthermore, we give a full classification of the…

Formal Languages and Automata Theory · Computer Science 2021-08-17 Stefan Hoffmann

In this work, we demonstrate the application of a first-order Taylor expansion to approximate a generic function $F: R^{n \times m} \to R^{n \times m}$ and utilize it in language modeling. To enhance the basic Taylor expansion, we introduce…

Computation and Language · Computer Science 2023-11-03 Davood Shamsi , Wen-yu Hua , Brian Williams

We study the complexity of problems solvable in deterministic polynomial time with access to an NP or Quantum Merlin-Arthur (QMA)-oracle, such as $P^{NP}$ and $P^{QMA}$, respectively. The former allows one to classify problems more finely…

Computational Complexity · Computer Science 2022-10-18 Sevag Gharibian , Dorian Rudolph

Series-parallel (SP) graphs are binary edge-labeled graphs with a designated source and target vertex, built using serial and parallel composition. A set of graphs is recognizable if membership depends only on its image under a homomorphism…

Formal Languages and Automata Theory · Computer Science 2026-04-28 Marius Bozga , Radu Iosif , Florian Zuleger

We improve the best known upper bound on the length of the shortest reset words of synchronizing automata. The new bound is slightly better than $114 n^3 / 685 + O(n^2)$. The \v{C}ern\'y conjecture states that $(n-1)^2$ is an upper bound.…

Formal Languages and Automata Theory · Computer Science 2018-04-02 Marek Szykuła

The problem of k-minimisation for a DFA M is the computation of a smallest DFA N (where the size |M| of a DFA M is the size of the domain of the transition function) such that their recognized languages differ only on words of length less…

Formal Languages and Automata Theory · Computer Science 2011-03-01 Paweł Gawrychowski , Artur Jeż , Andreas Maletti

Given a string $S$ of length $n$, the classic string indexing problem is to preprocess $S$ into a compact data structure that supports efficient subsequent pattern queries. In the \emph{deterministic} variant the goal is to solve the string…

Data Structures and Algorithms · Computer Science 2016-12-07 Philip Bille , Inge Li Gørtz , Frederik Rye Skjoldjensen

In this note we study automata recognizing birecurrent sets. A set of words is birecurrent if the minimal partial DFA recognizing this set and the minimal partial DFA recognizing the reversal of this set are both strongly connected. This…

Formal Languages and Automata Theory · Computer Science 2017-11-10 Andrew Ryzhikov

Given a non-deterministic finite automaton (NFA) A with m states, and a natural number n (presented in unary), the #NFA problem asks to determine the size of the set L(A_n) of words of length n accepted by A. While the corresponding…

Data Structures and Algorithms · Computer Science 2024-04-09 Kuldeep S. Meel , Sourav Chakraborty , Umang Mathur

We investigate a learning algorithm in the context of nominal automata, an extension of classical automata to alphabets featuring names. This class of automata captures nominal regular languages; analogously to the classical language…

Formal Languages and Automata Theory · Computer Science 2019-09-16 Yi Xiao , Emilio Tuosto

We consider the MAP-inference problem for graphical models, which is a valued constraint satisfaction problem defined on real numbers with a natural summation operation. We propose a family of relaxations (different from the famous…

Computer Vision and Pattern Recognition · Computer Science 2020-04-15 Stefan Haller , Paul Swoboda , Bogdan Savchynskyy

The maximum common subtree isomorphism problem asks for the largest possible isomorphism between subtrees of two given input trees. This problem is a natural restriction of the maximum common subgraph problem, which is ${\sf NP}$-hard in…

Data Structures and Algorithms · Computer Science 2016-08-23 Andre Droschinsky , Nils M. Kriege , Petra Mutzel

We prove the following theorem. Suppose that $M$ is a trim DFA on the Boolean alphabet $0,1$. The language $\L(M)$ is well-ordered by the lexicographic order $\slex$ iff whenever the non sink states $q,q.0$ are in the same strong component,…

Formal Languages and Automata Theory · Computer Science 2010-05-14 Stephen L. Bloom , YiDi Zhang