{"title":"Local permutation polynomials and their companions","authors":"Sartaj Ul Hasan, Hridesh Kumar","doi":"10.1016/j.ffa.2025.102717","DOIUrl":null,"url":null,"abstract":"<div><div>Gutierrez and Urroz (2023) have proposed a family of local permutation polynomials over finite fields of arbitrary characteristic based on a class of symmetric subgroups without fixed points called <em>e</em>-Klenian groups. The polynomials within this family are referred to as <em>e</em>-Klenian polynomials. Furthermore, they have shown the existence of companions for the <em>e</em>-Klenian polynomials when the characteristic of the finite field is odd. Here, we construct three new families of local permutation polynomials over finite fields of even characteristic, and derive a necessary and sufficient condition for each of these families to achieve the maximum possible degree. We also consider the problem of the existence of companions for the <em>e</em>-Klenian polynomials over finite fields of even characteristic. More precisely, we prove that over finite fields of even characteristic, the 0-Klenian polynomials do not have any companions. However, for <span><math><mi>e</mi><mo>≥</mo><mn>1</mn></math></span>, we explicitly provide a companion for the <em>e</em>-Klenian polynomials. Moreover, we provide a companion for each of the new families of local permutation polynomials that we introduce.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"109 ","pages":"Article 102717"},"PeriodicalIF":1.2000,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Finite Fields and Their Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1071579725001479","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
Gutierrez and Urroz (2023) have proposed a family of local permutation polynomials over finite fields of arbitrary characteristic based on a class of symmetric subgroups without fixed points called e-Klenian groups. The polynomials within this family are referred to as e-Klenian polynomials. Furthermore, they have shown the existence of companions for the e-Klenian polynomials when the characteristic of the finite field is odd. Here, we construct three new families of local permutation polynomials over finite fields of even characteristic, and derive a necessary and sufficient condition for each of these families to achieve the maximum possible degree. We also consider the problem of the existence of companions for the e-Klenian polynomials over finite fields of even characteristic. More precisely, we prove that over finite fields of even characteristic, the 0-Klenian polynomials do not have any companions. However, for , we explicitly provide a companion for the e-Klenian polynomials. Moreover, we provide a companion for each of the new families of local permutation polynomials that we introduce.
期刊介绍:
Finite Fields and Their Applications is a peer-reviewed technical journal publishing papers in finite field theory as well as in applications of finite fields. As a result of applications in a wide variety of areas, finite fields are increasingly important in several areas of mathematics, including linear and abstract algebra, number theory and algebraic geometry, as well as in computer science, statistics, information theory, and engineering.
For cohesion, and because so many applications rely on various theoretical properties of finite fields, it is essential that there be a core of high-quality papers on theoretical aspects. In addition, since much of the vitality of the area comes from computational problems, the journal publishes papers on computational aspects of finite fields as well as on algorithms and complexity of finite field-related methods.
The journal also publishes papers in various applications including, but not limited to, algebraic coding theory, cryptology, combinatorial design theory, pseudorandom number generation, and linear recurring sequences. There are other areas of application to be included, but the important point is that finite fields play a nontrivial role in the theory, application, or algorithm.