Counting strings over $\mathbb{Z}2^d$ with Given Elementary Symmetric Function Evaluations - Inria - Institut national de recherche en sciences et technologies du numérique
Communication Dans Un Congrès Discrete Mathematics and Theoretical Computer Science Année : 2013

Counting strings over $\mathbb{Z}2^d$ with Given Elementary Symmetric Function Evaluations

Résumé

Let $\alpha$ be a string over $\mathbb{Z}_q$, where $q = 2^d$. The $j$-th elementary symmetric function evaluated at $\alpha$ is denoted $e_j(\alpha)$ . We study the cardinalities $S_q(m;\mathcal{T} _1,\mathcal{T} _2,\ldots,\mathcal{T} _t)$ of the set of length $m$ strings for which $e_j(\alpha) = \tau _i$. The $\textit{profile}$ k$(\alpha) = ⟨k_1,k_2,\ldots,k_(q-1) ⟩$ of a string $\alpha$ is the sequence of frequencies with which each letter occurs. The profile of $\alpha$ determines $e_j(\alpha)$ , and hence $S_q$. Let $h_n$ : $\mathbb{Z}_{2^{n+d-1}}^{(q-1)}$ $\mapsto \mathbb{Z}_{2^d} [z] $ mod $ z^{2^n}$ be the map that takes k$(\alpha)$ mod $2^{n+d-1}$ to the polynomial $1+ e_1(\alpha) z + e_2(\alpha) z^2 + ⋯+ e_{2^n-1}(\alpha)$ $z^{2^{n-1}}$. We show that $h_n$ is a group homomorphism and establish necessary conditions for membership in the kernel for fixed $d$. The kernel is determined for $d$ = 2,3. The range of $h_n$ is described for $d$ = 2. These results are used to efficiently compute $S_4(m;\mathcal{T} _1,\mathcal{T} _2,\ldots,\mathcal{T} _t)$ for $d$ = 2 and the number of complete factorizations of certain polynomials.
Fichier principal
Vignette du fichier
dmAS0176.pdf (385.11 Ko) Télécharger le fichier
Origine Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-01229695 , version 1 (17-11-2015)

Identifiants

Citer

Charles Robert Miers, Franck Ruskey. Counting strings over $\mathbb{Z}2^d$ with Given Elementary Symmetric Function Evaluations. 25th International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2013), 2013, Paris, France. pp.897-908, ⟨10.46298/dmtcs.2352⟩. ⟨hal-01229695⟩

Collections

TDS-MACS
44 Consultations
784 Téléchargements

Altmetric

Partager

More