{"title":"Non-existence of some 4-dimensional Griesmer codes over finite fields","authors":"Kazuki Kumegawa, T. Maruta","doi":"10.13069/jacodesmath.427968","DOIUrl":"https://doi.org/10.13069/jacodesmath.427968","url":null,"abstract":"We prove the non--existence of $[g_q(4,d),4,d]_q$ codes for $d=2q^3-rq^2-2q+1$ for $3 le r le (q+1)/2$, $q ge 5$; $d=2q^3-3q^2-3q+1$ for $q ge 9$; $d=2q^3-4q^2-3q+1$ for $q ge 9$; and $d=q^3-q^2-rq-2$ with $r=4, 5$ or $6$ for $q ge 9$, where $g_q(4,d)=sum_{i=0}^{3} leftlceil d/q^i rightrceil$. This yields that $n_q(4,d) = g_q(4,d)+1$ for $2q^3-3q^2-3q+1 le d le 2q^3-3q^2$, $2q^3-5q^2-2q+1 le d le 2q^3-5q^2$ and $q^3-q^2-rq-2 le d le q^3-q^2-rq$ with $4 le r le 6$ for $q ge 9$ and that $n_q(4,d) ge g_q(4,d)+1$ for $2q^3-rq^2-2q+1 le d le 2q^3-rq^2-q$ for $3 le r le (q+1)/2$, $q ge 5$ and $2q^3-4q^2-3q+1 le d le 2q^3-4q^2-2q$ for $q ge 9$, where $n_q(4,d)$ denotes the minimum length $n$ for which an $[n,4,d]_q$ code exists.","PeriodicalId":37029,"journal":{"name":"Journal of Algebra Combinatorics Discrete Structures and Applications","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47232360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"$mathbb{Z}_{q}(mathbb{Z}_{q}+umathbb{Z}_{q})-$ linear skew constacyclic codes","authors":"A. Melakhessou, N. Aydin, K. Guenda","doi":"10.13069/jacodesmath.671815","DOIUrl":"https://doi.org/10.13069/jacodesmath.671815","url":null,"abstract":"In this paper, we study skew constacyclic codes over the ring $mathbb{Z}_{q}R$ where $R=mathbb{Z}_{q}+umathbb{Z}_{q}$, $q=p^{s}$ for a prime $p$ and $u^{2}=0$. We give the definition of these codes as subsets of the ring $mathbb{Z}_{q}^{alpha}R^{beta}$. Some structural properties of the skew polynomial ring $ R[x,theta]$ are discussed, where $ theta$ is an automorphism of $R$. We describe the generator polynomials of skew constacyclic codes over $ R $ and $mathbb{Z}_{q}R$. Using Gray images of skew constacyclic codes over $mathbb{Z}_{q}R$ we obtained some new linear codes over $mathbb{Z}_4$. Further, we have generalized these codes to double skew constacyclic codes over $mathbb{Z}_{q}R$.","PeriodicalId":37029,"journal":{"name":"Journal of Algebra Combinatorics Discrete Structures and Applications","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47575885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"One–generator quasi–abelian codes revisited","authors":"Somphong Jitman, P. Udomkavanich","doi":"10.13069/jacodesmath.09585","DOIUrl":"https://doi.org/10.13069/jacodesmath.09585","url":null,"abstract":"The class of 1-generator quasi-abelian codes over finite fields is revisited. Alternative and explicit characterization and enumeration of such codes are given. An algorithm to find all 1-generator quasi-abelian codes is provided. Two 1-generator quasi-abelian codes whose minimum distances are improved from Grassl’s online table are presented.","PeriodicalId":37029,"journal":{"name":"Journal of Algebra Combinatorics Discrete Structures and Applications","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66233241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Self-dual and complementary dual abelian codes over Galois rings","authors":"Somphong Jitman, S. Ling","doi":"10.13069/JACODESMATH.560406","DOIUrl":"https://doi.org/10.13069/JACODESMATH.560406","url":null,"abstract":"Self-dual and complementary dual cyclic/abelian codes over finite fields form important classes of linear codes that have been extensively studied due to their rich algebraic structures and wide applications. In this paper, abelian codes over Galois rings are studied in terms of the ideals in the group ring ${ GR}(p^r,s)[G]$, where $G$ is a finite abelian group and ${ GR}(p^r,s)$ is a Galois ring. Characterizations of self-dual abelian codes have been given together with necessary and sufficient conditions for the existence of a self-dual abelian code in ${ GR}(p^r,s)[G]$. A general formula for the number of such self-dual codes is established. In the case where $gcd(|G|,p)=1$, the number of self-dual abelian codes in ${ GR}(p^r,s)[G]$ is completely and explicitly determined. Applying known results on cyclic codes of length $p^a$ over ${ GR}(p^2,s)$, an explicit formula for the number of self-dual abelian codes in ${ GR}(p^2,s)[G]$ are given, where the Sylow $p$-subgroup of $G$ is cyclic. Subsequently, the characterization and enumeration of complementary dual abelian codes in ${ GR}(p^r,s)[G]$ are established. The analogous results for self-dual and complementary dual cyclic codes over Galois rings are therefore obtained as corollaries.","PeriodicalId":37029,"journal":{"name":"Journal of Algebra Combinatorics Discrete Structures and Applications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2014-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66232853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}