q-Parikh Matrices and q-deformed binomial coefficients of words

Fuente: arXiv
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Autores principales: Renard, Antoine, Rigo, Michel, Whiteland, Markus A.
Formato: Preprint
Publicado: 2024
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author Renard, Antoine
Rigo, Michel
Whiteland, Markus A.
author_facet Renard, Antoine
Rigo, Michel
Whiteland, Markus A.
contents We have introduced a q-deformation, i.e., a polynomial in q with natural coefficients, of the binomial coefficient of two finite words u and v counting the number of occurrences of v as a subword of u. In this paper, we examine the q-deformation of Parikh matrices as introduced by Eğecioğlu in 2004. Many classical results concerning Parikh matrices generalize to this new framework: Our first important observation is that the elements of such a matrix are in fact q-deformations of binomial coefficients of words. We also study their inverses and as an application, we obtain new identities about q-binomials. For a finite word z and for the sequence $(p_n)_{n\ge 0}$ of prefixes of an infinite word, we show that the polynomial sequence $\binom{p_n}{z}_q$ converges to a formal series. We present links with additive number theory and k-regular sequences. In the case of a periodic word $u^ω$, we generalize a result of Salomaa: the sequence $\binom{u^n}{z}_q$ satisfies a linear recurrence relation with polynomial coefficients. Related to the theory of integer partition, we describe the growth and the zero set of the coefficients of the series associated with $u^ω$. Finally, we show that the minors of a q-Parikh matrix are polynomials with natural coefficients and consider a generalization of Cauchy's inequality. We also compare q-Parikh matrices associated with an arbitrary word with those associated with a canonical word $12\cdots k$ made of pairwise distinct symbols.
format Preprint
id arxiv_https___arxiv_org_abs_2402_05657
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle q-Parikh Matrices and q-deformed binomial coefficients of words
Renard, Antoine
Rigo, Michel
Whiteland, Markus A.
Formal Languages and Automata Theory
Discrete Mathematics
Combinatorics
05A30, 68R15, 15B36, 11B85
We have introduced a q-deformation, i.e., a polynomial in q with natural coefficients, of the binomial coefficient of two finite words u and v counting the number of occurrences of v as a subword of u. In this paper, we examine the q-deformation of Parikh matrices as introduced by Eğecioğlu in 2004. Many classical results concerning Parikh matrices generalize to this new framework: Our first important observation is that the elements of such a matrix are in fact q-deformations of binomial coefficients of words. We also study their inverses and as an application, we obtain new identities about q-binomials. For a finite word z and for the sequence $(p_n)_{n\ge 0}$ of prefixes of an infinite word, we show that the polynomial sequence $\binom{p_n}{z}_q$ converges to a formal series. We present links with additive number theory and k-regular sequences. In the case of a periodic word $u^ω$, we generalize a result of Salomaa: the sequence $\binom{u^n}{z}_q$ satisfies a linear recurrence relation with polynomial coefficients. Related to the theory of integer partition, we describe the growth and the zero set of the coefficients of the series associated with $u^ω$. Finally, we show that the minors of a q-Parikh matrix are polynomials with natural coefficients and consider a generalization of Cauchy's inequality. We also compare q-Parikh matrices associated with an arbitrary word with those associated with a canonical word $12\cdots k$ made of pairwise distinct symbols.
title q-Parikh Matrices and q-deformed binomial coefficients of words
topic Formal Languages and Automata Theory
Discrete Mathematics
Combinatorics
05A30, 68R15, 15B36, 11B85
url https://arxiv.org/abs/2402.05657