Pub Date : 2025-12-03DOI: 10.1016/j.ffa.2025.102767
Kaimin Cheng , Arne Winterhof
Let q be a prime power and r a positive even integer. Let be the finite field with q elements and be its extension field of degree r. Let χ be a nontrivial multiplicative character of and a polynomial over with exactly one simple root in . In this paper, we improve estimates for character sums , where is either a subset of of sparse elements, with respect to some fixed basis of which contains a basis of , or a subset avoiding affine hyperplanes in general position. While such sums have been previously studied, our approach yields sharper bounds by reducing them to sums over the subfield rather than sums over general linear spaces. These estimates can be used to prove the existence of primitive elements in in the standard way.
{"title":"Multiplicative character sums over two classes of subsets of quadratic extensions of finite fields","authors":"Kaimin Cheng , Arne Winterhof","doi":"10.1016/j.ffa.2025.102767","DOIUrl":"10.1016/j.ffa.2025.102767","url":null,"abstract":"<div><div>Let <em>q</em> be a prime power and <em>r</em> a positive even integer. Let <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> be the finite field with <em>q</em> elements and <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi></mrow></msup></mrow></msub></math></span> be its extension field of degree <em>r</em>. Let <em>χ</em> be a nontrivial multiplicative character of <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi></mrow></msup></mrow></msub></math></span> and <span><math><mi>f</mi><mo>(</mo><mi>X</mi><mo>)</mo></math></span> a polynomial over <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi></mrow></msup></mrow></msub></math></span> with exactly one simple root in <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi></mrow></msup></mrow></msub></math></span>. In this paper, we improve estimates for character sums <span><math><munder><mo>∑</mo><mrow><mi>g</mi><mo>∈</mo><mi>G</mi></mrow></munder><mi>χ</mi><mo>(</mo><mi>f</mi><mo>(</mo><mi>g</mi><mo>)</mo><mo>)</mo></math></span>, where <span><math><mi>G</mi></math></span> is either a subset of <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi></mrow></msup></mrow></msub></math></span> of sparse elements, with respect to some fixed basis of <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi></mrow></msup></mrow></msub></math></span> which contains a basis of <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi><mo>/</mo><mn>2</mn></mrow></msup></mrow></msub></math></span>, or a subset avoiding affine hyperplanes in general position. While such sums have been previously studied, our approach yields sharper bounds by reducing them to sums over the subfield <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>r</mi><mo>/</mo><mn>2</mn></mrow></msup></mrow></msub></math></span> rather than sums over general linear spaces. These estimates can be used to prove the existence of primitive elements in <span><math><mi>G</mi></math></span> in the standard way.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102767"},"PeriodicalIF":1.2,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-02DOI: 10.1016/j.ffa.2025.102766
I. Cardinali , L. Giuzzi
Let V be a vector space over the finite field with q elements and Λ be the image of the Segre geometry in under the Segre map. Consider the subvariety of Λ represented by the pure tensors with and such that . Regarding as a projective system of , we study the linear code arising from it. We show that is a minimal code and we determine its basic parameters, its full weight list and its linear automorphism group. We also give a geometrical characterization of its minimum and second lowest weight codewords as well as of some of the words of maximum weight.
{"title":"Linear codes arising from the point-hyperplane geometry-Part I: The Segre embedding","authors":"I. Cardinali , L. Giuzzi","doi":"10.1016/j.ffa.2025.102766","DOIUrl":"10.1016/j.ffa.2025.102766","url":null,"abstract":"<div><div>Let <em>V</em> be a vector space over the finite field <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> with <em>q</em> elements and Λ be the image of the Segre geometry <span><math><mrow><mi>PG</mi></mrow><mo>(</mo><mi>V</mi><mo>)</mo><mo>⊗</mo><mrow><mi>PG</mi></mrow><mo>(</mo><msup><mrow><mi>V</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>)</mo></math></span> in <span><math><mrow><mi>PG</mi></mrow><mo>(</mo><mi>V</mi><mo>⊗</mo><msup><mrow><mi>V</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>)</mo></math></span> under the Segre map. Consider the subvariety <span><math><msub><mrow><mi>Λ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> of Λ represented by the pure tensors <span><math><mi>x</mi><mo>⊗</mo><mi>ξ</mi></math></span> with <span><math><mi>x</mi><mo>∈</mo><mi>V</mi></math></span> and <span><math><mi>ξ</mi><mo>∈</mo><msup><mrow><mi>V</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span> such that <span><math><mi>ξ</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>=</mo><mn>0</mn></math></span>. Regarding <span><math><msub><mrow><mi>Λ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> as a projective system of <span><math><mrow><mi>PG</mi></mrow><mo>(</mo><mi>V</mi><mo>⊗</mo><msup><mrow><mi>V</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>)</mo></math></span>, we study the linear code <span><math><mi>C</mi><mo>(</mo><msub><mrow><mi>Λ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>)</mo></math></span> arising from it. We show that <span><math><mi>C</mi><mo>(</mo><msub><mrow><mi>Λ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>)</mo></math></span> is a minimal code and we determine its basic parameters, its full weight list and its linear automorphism group. We also give a geometrical characterization of its minimum and second lowest weight codewords as well as of some of the words of maximum weight.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102766"},"PeriodicalIF":1.2,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ffa.2025.102760
Liqin Qian , Minjia Shi , Xiwang Cao
In this paper, we propose several classes of permutation polynomials of the form over , where , and . The permutation behavior of the proposed polynomials is investigated by the AGW criterion and determination of the number of solutions to certain equations over . Based on an effective method proposed by Mesnager (2014), we construct several classes of involutions and further obtain some self-dual bent functions by employing three permutations of satisfying an algebraic property . Finally, it is worth pointing out that there exist examples of bent functions we obtained which do not belong to .
{"title":"Permutation polynomials and involutions over the finite field F22m","authors":"Liqin Qian , Minjia Shi , Xiwang Cao","doi":"10.1016/j.ffa.2025.102760","DOIUrl":"10.1016/j.ffa.2025.102760","url":null,"abstract":"<div><div>In this paper, we propose several classes of permutation polynomials of the form <span><math><munderover><mo>∑</mo><mrow><mi>j</mi><mo>=</mo><mn>1</mn></mrow><mrow><mi>t</mi></mrow></munderover><msup><mrow><mo>(</mo><msubsup><mrow><mi>Tr</mi></mrow><mrow><mi>m</mi></mrow><mrow><mn>2</mn><mi>m</mi></mrow></msubsup><msup><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow><mrow><msub><mrow><mi>k</mi></mrow><mrow><mi>j</mi></mrow></msub></mrow></msup><mo>+</mo><msub><mrow><mi>δ</mi></mrow><mrow><mi>j</mi></mrow></msub><mo>)</mo></mrow><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>j</mi></mrow></msub></mrow></msup><mo>+</mo><mi>L</mi><mo>(</mo><mi>x</mi><mo>)</mo></math></span> over <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mn>2</mn></mrow><mrow><mn>2</mn><mi>m</mi></mrow></msup></mrow></msub></math></span>, where <span><math><mi>L</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>=</mo><mi>a</mi><msubsup><mrow><mi>Tr</mi></mrow><mrow><mi>m</mi></mrow><mrow><mn>2</mn><mi>m</mi></mrow></msubsup><mo>(</mo><mi>x</mi><mo>)</mo><mo>+</mo><mi>b</mi><mi>x</mi></math></span>, <span><math><mi>a</mi><mo>∈</mo><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mn>2</mn></mrow><mrow><mn>2</mn><mi>m</mi></mrow></msup></mrow></msub></math></span> and <span><math><mi>b</mi><mo>∈</mo><msubsup><mrow><mi>F</mi></mrow><mrow><msup><mrow><mn>2</mn></mrow><mrow><mi>m</mi></mrow></msup></mrow><mrow><mo>⁎</mo></mrow></msubsup></math></span>. The permutation behavior of the proposed polynomials is investigated by the AGW criterion and determination of the number of solutions to certain equations over <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mn>2</mn></mrow><mrow><mn>2</mn><mi>m</mi></mrow></msup></mrow></msub></math></span>. Based on an effective method proposed by Mesnager (2014), we construct several classes of involutions and further obtain some self-dual bent functions by employing three permutations of <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mn>2</mn></mrow><mrow><mn>2</mn><mi>m</mi></mrow></msup></mrow></msub></math></span> satisfying an algebraic property <span><math><mo>(</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>2</mn><mi>m</mi></mrow></msub><mo>)</mo></math></span>. Finally, it is worth pointing out that there exist examples of bent functions we obtained which do not belong to <span><math><mi>M</mi><msup><mrow><mi>M</mi></mrow><mrow><mi>#</mi></mrow></msup></math></span>.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102760"},"PeriodicalIF":1.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ffa.2025.102765
Haode Yan
In this paper, we study the duals of BCH codes and . By analyzing the number of solutions to certain equations over the multiplicative subgroup of , we determine the possible weights of codewords in and , respectively. The weight distributions of these two dual codes are derived by applying the Pless power moments. Our results provide affirmative solutions to recent conjectures.
{"title":"On two conjectures of the duals of AMDS BCH codes","authors":"Haode Yan","doi":"10.1016/j.ffa.2025.102765","DOIUrl":"10.1016/j.ffa.2025.102765","url":null,"abstract":"<div><div>In this paper, we study the duals of BCH codes <span><math><msub><mrow><mi>C</mi></mrow><mrow><mo>(</mo><mi>q</mi><mo>,</mo><mi>q</mi><mo>+</mo><mn>1</mn><mo>,</mo><mn>3</mn><mo>,</mo><mfrac><mrow><mi>p</mi><mo>−</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>)</mo></mrow></msub></math></span> and <span><math><msub><mrow><mi>C</mi></mrow><mrow><mo>(</mo><msup><mrow><mn>3</mn></mrow><mrow><mi>s</mi></mrow></msup><mo>,</mo><msup><mrow><mn>3</mn></mrow><mrow><mi>s</mi></mrow></msup><mo>+</mo><mn>1</mn><mo>,</mo><mn>3</mn><mo>,</mo><mn>4</mn><mo>)</mo></mrow></msub></math></span>. By analyzing the number of solutions to certain equations over the multiplicative subgroup <span><math><msub><mrow><mi>U</mi></mrow><mrow><mi>q</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>=</mo><mo>{</mo><mi>x</mi><mo>∈</mo><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></msub><mo>:</mo><msup><mrow><mi>x</mi></mrow><mrow><mi>q</mi><mo>+</mo><mn>1</mn></mrow></msup><mo>=</mo><mn>1</mn><mo>}</mo></math></span> of <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow><mrow><mo>⁎</mo></mrow></msubsup></math></span>, we determine the possible weights of codewords in <span><math><msubsup><mrow><mi>C</mi></mrow><mrow><mo>(</mo><mi>q</mi><mo>,</mo><mi>q</mi><mo>+</mo><mn>1</mn><mo>,</mo><mn>3</mn><mo>,</mo><mfrac><mrow><mi>p</mi><mo>−</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>)</mo></mrow><mrow><mo>⊥</mo></mrow></msubsup></math></span> and <span><math><msubsup><mrow><mi>C</mi></mrow><mrow><mo>(</mo><msup><mrow><mn>3</mn></mrow><mrow><mi>s</mi></mrow></msup><mo>,</mo><msup><mrow><mn>3</mn></mrow><mrow><mi>s</mi></mrow></msup><mo>+</mo><mn>1</mn><mo>,</mo><mn>3</mn><mo>,</mo><mn>4</mn><mo>)</mo></mrow><mrow><mo>⊥</mo></mrow></msubsup></math></span>, respectively. The weight distributions of these two dual codes are derived by applying the Pless power moments. Our results provide affirmative solutions to recent conjectures.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102765"},"PeriodicalIF":1.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ffa.2025.102764
Fengwei Li, Yuting Liu, Ruiyuan Jiang
Let be the finite field with q elements, where q is a power of an odd prime p. In this paper, we provide a method to construct Hermitian self-orthogonal generalized Reed-Solomon (GRS) codes and extended GRS codes, which their support sets are roots of polynomials from affine and projective linear transformation over . Moreover, we construct three classes of quantum maximum distance separable (MDS) codes with minimum distances . Some of these quantum MDS codes have not been obtained before, and in some cases, have larger minimum distances and higher efficiency than the well-known quantum MDS codes.
{"title":"Quantum MDS codes induced by the projective linear transformation","authors":"Fengwei Li, Yuting Liu, Ruiyuan Jiang","doi":"10.1016/j.ffa.2025.102764","DOIUrl":"10.1016/j.ffa.2025.102764","url":null,"abstract":"<div><div>Let <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> be the finite field with <em>q</em> elements, where <em>q</em> is a power of an odd prime <em>p</em>. In this paper, we provide a method to construct Hermitian self-orthogonal generalized Reed-Solomon (GRS) codes and extended GRS codes, which their support sets are roots of polynomials from affine and projective linear transformation over <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></msub></math></span>. Moreover, we construct three classes of quantum maximum distance separable (MDS) codes with minimum distances <span><math><mo>></mo><mfrac><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></mfrac><mo>+</mo><mn>1</mn></math></span>. Some of these quantum MDS codes have not been obtained before, and in some cases, have larger minimum distances and higher efficiency than the well-known quantum MDS codes.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102764"},"PeriodicalIF":1.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-26DOI: 10.1016/j.ffa.2025.102763
Krishna Kaipa , Puspendu Pradhan
We consider the problem of classifying the lines of the projective 3-space over a finite field into orbits of the group of linear symmetries of the twisted cubic C. The problem has been solved in literature in characteristic different from 3, and in this work, we solve the problem in characteristic 3. We reduce this problem to another problem, which is the classification of binary quartic forms into -orbits. We first solve the latter problem and use to solve the former problem. We also obtain the point-line and the line-plane incidence structures of the point, line, and plane orbits.
{"title":"On the PGL2(q)-orbits of lines of PG(3,q) and binary quartic forms in characteristic three","authors":"Krishna Kaipa , Puspendu Pradhan","doi":"10.1016/j.ffa.2025.102763","DOIUrl":"10.1016/j.ffa.2025.102763","url":null,"abstract":"<div><div>We consider the problem of classifying the lines of the projective 3-space <span><math><mi>P</mi><mi>G</mi><mo>(</mo><mn>3</mn><mo>,</mo><mi>q</mi><mo>)</mo></math></span> over a finite field <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> into orbits of the group <span><math><mi>P</mi><mi>G</mi><msub><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>q</mi><mo>)</mo></math></span> of linear symmetries of the twisted cubic <em>C</em>. The problem has been solved in literature in characteristic different from 3, and in this work, we solve the problem in characteristic 3. We reduce this problem to another problem, which is the classification of binary quartic forms into <span><math><mi>P</mi><mi>G</mi><msub><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>q</mi><mo>)</mo></math></span>-orbits. We first solve the latter problem and use to solve the former problem. We also obtain the point-line and the line-plane incidence structures of the point, line, and plane orbits.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102763"},"PeriodicalIF":1.2,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145624274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-25DOI: 10.1016/j.ffa.2025.102761
Li Zhu , Jinle Liu , Hongfeng Wu
Cyclotomic coset is a classical notion in the theory of finite fields which has wide applications in various computation problems. Let q be a prime power, and n be a positive integer coprime to q. In this paper we determine explicitly the representatives and the sizes of all q-cyclotomic cosets modulo n in the general settings. We introduce the definition of 2-adic cyclotomic system, which is a profinite space consists of certain compatible sequences of cyclotomic cosets. A precise characterization of the structure of the 2-adic cyclotomic system is given, which reveals the general formula for representatives of cyclotomic cosets. With the representatives and the sizes of q-cyclotomic cosets modulo n, we improve the formulas for the factorizations of and of over given in [4]. As a consequence, we classify the cyclic codes over finite fields via giving their generator polynomials. Moreover, the self-dual cyclic codes are determined and enumerated.
{"title":"Explicit representatives and sizes of cyclotomic cosets and their application to cyclic codes over finite fields","authors":"Li Zhu , Jinle Liu , Hongfeng Wu","doi":"10.1016/j.ffa.2025.102761","DOIUrl":"10.1016/j.ffa.2025.102761","url":null,"abstract":"<div><div>Cyclotomic coset is a classical notion in the theory of finite fields which has wide applications in various computation problems. Let <em>q</em> be a prime power, and <em>n</em> be a positive integer coprime to <em>q</em>. In this paper we determine explicitly the representatives and the sizes of all <em>q</em>-cyclotomic cosets modulo <em>n</em> in the general settings. We introduce the definition of 2-adic cyclotomic system, which is a profinite space consists of certain compatible sequences of cyclotomic cosets. A precise characterization of the structure of the 2-adic cyclotomic system is given, which reveals the general formula for representatives of cyclotomic cosets. With the representatives and the sizes of <em>q</em>-cyclotomic cosets modulo <em>n</em>, we improve the formulas for the factorizations of <span><math><msup><mrow><mi>X</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>−</mo><mn>1</mn></math></span> and of <span><math><msub><mrow><mi>Φ</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>(</mo><mi>X</mi><mo>)</mo></math></span> over <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> given in <span><span>[4]</span></span>. As a consequence, we classify the cyclic codes over finite fields via giving their generator polynomials. Moreover, the self-dual cyclic codes are determined and enumerated.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102761"},"PeriodicalIF":1.2,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145624202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-25DOI: 10.1016/j.ffa.2025.102759
A.M. Maksaev, N.Y. Medved, V.V. Promyslov
Denote by the space of all matrices over a field. For a fixed , we investigate bijective maps such that iff , for any . When , we not only characterize such maps on matrix spaces, but prove that such maps are equal isometries even on more general metric spaces that we call discrete-triangular. For an arbitrary k, we prove that the same characterization holds for the matrices over finite fields, except for matrices over the field of 2 elements. To do this, we use theory of association schemes, specifically the bilinear forms scheme, and investigate its eigenvalues and intersection numbers.
{"title":"Maps preserving a fixed rank-distance on matrices over finite fields","authors":"A.M. Maksaev, N.Y. Medved, V.V. Promyslov","doi":"10.1016/j.ffa.2025.102759","DOIUrl":"10.1016/j.ffa.2025.102759","url":null,"abstract":"<div><div>Denote by <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>m</mi><mo>×</mo><mi>n</mi></mrow></msub></math></span> the space of all <span><math><mi>m</mi><mo>×</mo><mi>n</mi></math></span> matrices over a field. For a fixed <span><math><mn>1</mn><mo>⩽</mo><mi>k</mi><mo>⩽</mo><mi>min</mi><mo></mo><mo>(</mo><mi>m</mi><mo>,</mo><mi>n</mi><mo>)</mo></math></span>, we investigate bijective maps <span><math><msub><mrow><mi>φ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>:</mo><msub><mrow><mi>M</mi></mrow><mrow><mi>m</mi><mo>×</mo><mi>n</mi></mrow></msub><mo>→</mo><msub><mrow><mi>M</mi></mrow><mrow><mi>m</mi><mo>×</mo><mi>n</mi></mrow></msub></math></span> such that <span><math><mi>rk</mi><mo>(</mo><mi>A</mi><mo>−</mo><mi>B</mi><mo>)</mo><mo>=</mo><mi>k</mi></math></span> iff <span><math><mi>rk</mi><mo>(</mo><msub><mrow><mi>φ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>(</mo><mi>A</mi><mo>)</mo><mo>−</mo><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>B</mi><mo>)</mo><mo>)</mo><mo>=</mo><mi>k</mi></math></span>, for any <span><math><mi>A</mi><mo>,</mo><mspace></mspace><mi>B</mi><mo>∈</mo><msub><mrow><mi>M</mi></mrow><mrow><mi>m</mi><mo>×</mo><mi>n</mi></mrow></msub></math></span>. When <span><math><mi>k</mi><mo><</mo><mi>min</mi><mo></mo><mo>(</mo><mi>m</mi><mo>,</mo><mi>n</mi><mo>)</mo><mo>/</mo><mn>2</mn></math></span>, we not only characterize such maps on matrix spaces, but prove that such maps are equal isometries even on more general metric spaces that we call discrete-triangular. For an arbitrary <em>k</em>, we prove that the same characterization holds for the matrices over finite fields, except for <span><math><mn>2</mn><mo>×</mo><mn>2</mn></math></span> matrices over the field of 2 elements. To do this, we use theory of association schemes, specifically the bilinear forms scheme, and investigate its eigenvalues and intersection numbers.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102759"},"PeriodicalIF":1.2,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145624275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-21DOI: 10.1016/j.ffa.2025.102762
John Bamberg , Geertrui Van de Voorde
The Hermitian Veronesean in , given by , is a well-studied rational curve, and forms a special set of the Hermitian surface . In this paper, we give two local characterisations of the Hermitian Veronesean, based on sublines and triples of points in perspective.
{"title":"On the Hermitian Veronesean","authors":"John Bamberg , Geertrui Van de Voorde","doi":"10.1016/j.ffa.2025.102762","DOIUrl":"10.1016/j.ffa.2025.102762","url":null,"abstract":"<div><div>The Hermitian Veronesean in <span><math><mrow><mi>PG</mi></mrow><mo>(</mo><mn>3</mn><mo>,</mo><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></math></span>, given by <span><math><mi>V</mi><mo>:</mo><mo>=</mo><mo>{</mo><mo>(</mo><mn>1</mn><mo>,</mo><mi>x</mi><mo>,</mo><msup><mrow><mi>x</mi></mrow><mrow><mi>q</mi></mrow></msup><mo>,</mo><msup><mrow><mi>x</mi></mrow><mrow><mi>q</mi><mo>+</mo><mn>1</mn></mrow></msup><mo>)</mo><mo>:</mo><mi>x</mi><mo>∈</mo><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></msub><mo>}</mo><mo>∪</mo><mo>{</mo><mo>(</mo><mn>0</mn><mo>,</mo><mn>0</mn><mo>,</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>}</mo></math></span>, is a well-studied rational curve, and forms a <em>special</em> set of the Hermitian surface <span><math><mi>H</mi><mo>(</mo><mn>3</mn><mo>,</mo><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></math></span>. In this paper, we give two local characterisations of the Hermitian Veronesean, based on sublines and triples of points in perspective.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102762"},"PeriodicalIF":1.2,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145580235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-20DOI: 10.1016/j.ffa.2025.102753
Guido Lido
We describe a provably quasi-polynomial algorithm to compute discrete logarithms in the multiplicative groups of finite fields of small characteristic, that is finite fields whose characteristic is logarithmic in the order. We partially follow the heuristically quasi-polynomial algorithm presented by Barbulescu, Gaudry, Joux and Thomé. The main difference is to use a presentation of the finite field based on elliptic curves: the abundance of elliptic curves ensures the existence of such a presentation.
{"title":"A provably quasi-polynomial algorithm for the discrete logarithm problem in finite fields of small characteristic","authors":"Guido Lido","doi":"10.1016/j.ffa.2025.102753","DOIUrl":"10.1016/j.ffa.2025.102753","url":null,"abstract":"<div><div>We describe a provably quasi-polynomial algorithm to compute discrete logarithms in the multiplicative groups of finite fields of small characteristic, that is finite fields whose characteristic is logarithmic in the order. We partially follow the heuristically quasi-polynomial algorithm presented by Barbulescu, Gaudry, Joux and Thomé. The main difference is to use a presentation of the finite field based on elliptic curves: the abundance of elliptic curves ensures the existence of such a presentation.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102753"},"PeriodicalIF":1.2,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145546710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}