Learning Deterministic One-Counter Automata in Polynomial Time

Fuente: arXiv
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Autori principali: Mathew, Prince, Penelle, Vincent, Sreejith, A. V.
Natura: Preprint
Pubblicazione: 2025
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author Mathew, Prince
Penelle, Vincent
Sreejith, A. V.
author_facet Mathew, Prince
Penelle, Vincent
Sreejith, A. V.
contents We give an active learning algorithm for deterministic one-counter automata (DOCAs) where the learner can ask the teacher membership and minimal equivalence queries. The algorithm called OL* learns a DOCA in time polynomial in the size of the smallest DOCA, recognising the target language. All existing algorithms for learning DOCAs, even for the subclasses of deterministic real-time one-counter automata (DROCAs) and visibly one-counter automata (VOCAs), in the worst case, run in exponential time with respect to the size of the DOCA under learning. Furthermore, previous learning algorithms are ``grey-box'' algorithms relying on an additional query type - counter value query - where the teacher returns the counter value reached on reading a given word. In contrast, our algorithm is a ``black-box'' algorithm. It is known that the minimisation of VOCAs is NP-hard. However, OL* can be used for approximate minimisation of DOCAs. In this case, the output size is at most polynomial in the size of a minimal DOCA.
format Preprint
id arxiv_https___arxiv_org_abs_2503_04525
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Learning Deterministic One-Counter Automata in Polynomial Time
Mathew, Prince
Penelle, Vincent
Sreejith, A. V.
Formal Languages and Automata Theory
Logic in Computer Science
F.3.1; F.4.3
We give an active learning algorithm for deterministic one-counter automata (DOCAs) where the learner can ask the teacher membership and minimal equivalence queries. The algorithm called OL* learns a DOCA in time polynomial in the size of the smallest DOCA, recognising the target language. All existing algorithms for learning DOCAs, even for the subclasses of deterministic real-time one-counter automata (DROCAs) and visibly one-counter automata (VOCAs), in the worst case, run in exponential time with respect to the size of the DOCA under learning. Furthermore, previous learning algorithms are ``grey-box'' algorithms relying on an additional query type - counter value query - where the teacher returns the counter value reached on reading a given word. In contrast, our algorithm is a ``black-box'' algorithm. It is known that the minimisation of VOCAs is NP-hard. However, OL* can be used for approximate minimisation of DOCAs. In this case, the output size is at most polynomial in the size of a minimal DOCA.
title Learning Deterministic One-Counter Automata in Polynomial Time
topic Formal Languages and Automata Theory
Logic in Computer Science
F.3.1; F.4.3
url https://arxiv.org/abs/2503.04525