Approximate NFA universality and related problems motivated by information theory & nbsp;

• Type: Article in International Scientific Journal
• Date: 2023

Authors

Konstantinidis, S (Author) Other; Mastnak, M (Author) Other; Nelma Moreira (Author) FCUP; Rogério Reis (Author) FCUP

Journal

Title: Theoretical Computer Science

Vol. 972

ISSN: 0304-3975

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 1 Citation

Scopus - 1 Citation

Other information

Authenticus ID: P-00Y-RXY

DOI: 10.1016/j.tcs.2023.114076

Abstract (EN): In coding and information theory, it is desirable to construct maximal codes that can be either variable length codes or error control codes of fixed length. However deciding code maximality boils down to deciding whether a given NFA is universal, and this is a hard problem (including the case of whether the NFA accepts all words of a fixed length). On the other hand, it is acceptable to know whether a code is 'approximately' maximal, which then boils down to whether a given NFA is 'approximately' universal. Here we introduce the notion of a (1 - & epsilon;)-universal automaton and present polynomial randomized approximation algorithms to test NFA universality and related hard automata problems, for certain natural probability distributions on the set of words. We also conclude that the randomization aspect is necessary, as approximate universality remains hard for any fixed polynomially computable & epsilon;.& COPY; 2023 Elsevier B.V. All rights reserved.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16