Weakly-unambiguous Parikh automata and their link to holonomic series

Fuente: arXiv
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Main Authors: Bostan, Alin, Carayol, Arnaud, Koechlin, Florent, Nicaud, Cyril
Format: Preprint
Published: 2025
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author Bostan, Alin
Carayol, Arnaud
Koechlin, Florent
Nicaud, Cyril
author_facet Bostan, Alin
Carayol, Arnaud
Koechlin, Florent
Nicaud, Cyril
contents We investigate the connection between properties of formal languages and properties of their generating series, with a focus on the class of holonomic power series. We first prove a strong version of a conjecture by Castiglione and Massazza: weakly-unambiguous Parikh automata are equivalent to unambiguous two-way reversal bounded counter machines, and their multivariate generating series are holonomic. We then show that the converse is not true: we construct a language whose generating series is algebraic (thus holonomic), but which is inherently weakly-ambiguous as a Parikh automata language. Finally, we prove an effective decidability result for the inclusion problem for weakly-unambiguous Parikh automata, and provide an upper-bound on to its complexity.
format Preprint
id arxiv_https___arxiv_org_abs_2512_09823
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Weakly-unambiguous Parikh automata and their link to holonomic series
Bostan, Alin
Carayol, Arnaud
Koechlin, Florent
Nicaud, Cyril
Formal Languages and Automata Theory
Symbolic Computation
68Q45
We investigate the connection between properties of formal languages and properties of their generating series, with a focus on the class of holonomic power series. We first prove a strong version of a conjecture by Castiglione and Massazza: weakly-unambiguous Parikh automata are equivalent to unambiguous two-way reversal bounded counter machines, and their multivariate generating series are holonomic. We then show that the converse is not true: we construct a language whose generating series is algebraic (thus holonomic), but which is inherently weakly-ambiguous as a Parikh automata language. Finally, we prove an effective decidability result for the inclusion problem for weakly-unambiguous Parikh automata, and provide an upper-bound on to its complexity.
title Weakly-unambiguous Parikh automata and their link to holonomic series
topic Formal Languages and Automata Theory
Symbolic Computation
68Q45
url https://arxiv.org/abs/2512.09823