{"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":"2026-03-01","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}
{"title":"Kneser's theorem for codes and ℓ-divisible set families","authors":"Chenying Lin , Gilles Zémor","doi":"10.1016/j.ffa.2025.102783","DOIUrl":"10.1016/j.ffa.2025.102783","url":null,"abstract":"<div><div>A <em>k</em>-wise <em>ℓ</em>-divisible set family is a collection <span><math><mi>F</mi></math></span> of subsets of <span><math><mo>{</mo><mn>1</mn><mo>,</mo><mo>…</mo><mo>,</mo><mi>n</mi><mo>}</mo></math></span> such that any intersection of <em>k</em> sets in <span><math><mi>F</mi></math></span> has cardinality divisible by <em>ℓ</em>. If <span><math><mi>k</mi><mo>=</mo><mi>ℓ</mi><mo>=</mo><mn>2</mn></math></span>, it is well-known that <span><math><mo>|</mo><mi>F</mi><mo>|</mo><mo>≤</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>⌊</mo><mi>n</mi><mo>/</mo><mn>2</mn><mo>⌋</mo></mrow></msup></math></span>. We generalise this by proving that <span><math><mo>|</mo><mi>F</mi><mo>|</mo><mo>≤</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>⌊</mo><mi>n</mi><mo>/</mo><mi>p</mi><mo>⌋</mo></mrow></msup></math></span> if <span><math><mi>k</mi><mo>=</mo><mi>ℓ</mi><mo>=</mo><mi>p</mi></math></span>, for any prime number <em>p</em>.</div><div>For arbitrary values of <em>ℓ</em>, we prove that <span><math><mn>4</mn><msup><mrow><mi>ℓ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>-wise <em>ℓ</em>-divisible set families <span><math><mi>F</mi></math></span> satisfy <span><math><mo>|</mo><mi>F</mi><mo>|</mo><mo>≤</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>⌊</mo><mi>n</mi><mo>/</mo><mi>ℓ</mi><mo>⌋</mo></mrow></msup></math></span> and that the only families achieving the upper bound are atomic, meaning that they consist of all the unions of disjoint subsets of size <em>ℓ</em>. This improves upon a recent result by Gishboliner, Sudakov and Timon, that arrived at the same conclusion for <em>k</em>-wise <em>ℓ</em>-divisible families, with values of <em>k</em> that behave exponentially in <em>ℓ</em>.</div><div>Our techniques rely heavily upon a coding-theory analogue of Kneser's Theorem from additive combinatorics.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102783"},"PeriodicalIF":1.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790234","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}
Carlos Galindo , Fernando Hernando , Helena Martín-Cruz , Ryutaroh Matsumoto
{"title":"Quantum (r,δ)-locally recoverable codes","authors":"Carlos Galindo , Fernando Hernando , Helena Martín-Cruz , Ryutaroh Matsumoto","doi":"10.1016/j.ffa.2025.102785","DOIUrl":"10.1016/j.ffa.2025.102785","url":null,"abstract":"<div><div>Classical <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-locally recoverable codes are designed for avoiding loss of information in large scale distributed and cloud storage systems. We introduce the quantum counterpart of those codes by defining quantum <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-locally recoverable codes which are quantum error-correcting codes capable of correcting <span><math><mi>δ</mi><mo>−</mo><mn>1</mn></math></span> qudit erasures from sets of at most <span><math><mi>r</mi><mo>+</mo><mi>δ</mi><mo>−</mo><mn>1</mn></math></span> qudits.</div><div>We give a necessary and sufficient condition for a quantum stabilizer code <span><math><mi>Q</mi><mo>(</mo><mi>C</mi><mo>)</mo></math></span> to be <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-locally recoverable. Our condition depends only on the puncturing and shortening at suitable sets of both the symplectic self-orthogonal code <em>C</em> used for constructing <span><math><mi>Q</mi><mo>(</mo><mi>C</mi><mo>)</mo></math></span> and its symplectic dual <span><math><msup><mrow><mi>C</mi></mrow><mrow><msub><mrow><mo>⊥</mo></mrow><mrow><mi>s</mi></mrow></msub></mrow></msup></math></span>. When <span><math><mi>Q</mi><mo>(</mo><mi>C</mi><mo>)</mo></math></span> comes from a Hermitian or Euclidean dual-containing code, and under an extra condition, we show that there is an equivalence between the classical and quantum concepts of <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-local recoverability. A Singleton-like bound is stated in this case and examples attaining the bound are given.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102785"},"PeriodicalIF":1.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883541","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}
{"title":"A family of optimal dual-containing and reversible linear codes over F4","authors":"Sujata Bansal, Pramod Kumar Kewat","doi":"10.1016/j.ffa.2025.102777","DOIUrl":"10.1016/j.ffa.2025.102777","url":null,"abstract":"<div><div>In this paper, we construct a family of optimal linear codes over <span><math><msub><mrow><mi>F</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span> with parameters <span><math><mo>[</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>e</mi></mrow></msup><mo>,</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>e</mi></mrow></msup><mo>−</mo><mi>e</mi><mo>−</mo><mn>1</mn><mo>,</mo><mn>4</mn><mo>]</mo></math></span>, where <em>e</em> is a positive integer and <span><math><mi>e</mi><mo>≥</mo><mn>2</mn></math></span>. We determine the duals of these codes and establish that for <span><math><mi>e</mi><mo>≥</mo><mn>3</mn></math></span>, these codes are dual-containing. This property makes them suitable for the construction of CSS quantum error-correcting codes. Furthermore, we calculate the weight distribution of the duals of these codes and show that the duals are 3-weight codes. We derive the weight enumerator of these codes using the MacWilliams identities. Additionally, we establish that these codes are reversible for all <span><math><mi>e</mi><mo>≥</mo><mn>2</mn></math></span>. This ensures the symmetry in the code structure and facilitates them for the possible applications in DNA computing and bidirectional communication systems. The optimality, duality, and reversibility of this family of codes highlight the potential of these codes for various practical and theoretical applications in the error correction.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102777"},"PeriodicalIF":1.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737312","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}
Sarah Arpin , Ross Bowden , James Clements , Wissam Ghantous , Jason T. LeGrow , Krystal Maughan
{"title":"Cycles and cuts in supersingular L-isogeny graphs","authors":"Sarah Arpin , Ross Bowden , James Clements , Wissam Ghantous , Jason T. LeGrow , Krystal Maughan","doi":"10.1016/j.ffa.2025.102768","DOIUrl":"10.1016/j.ffa.2025.102768","url":null,"abstract":"<div><div>Supersingular elliptic curve isogeny graphs underlie isogeny-based cryptography. For isogenies of a single prime degree <em>ℓ</em>, their structure has been investigated graph-theoretically. We generalise the notion of <em>ℓ</em>-isogeny graphs to <em>L</em>-isogeny graphs (studied in the prime field case by Delfs and Galbraith), where <em>L</em> is a set of small primes dictating the allowed isogeny degrees in the graph. We analyse the graph-theoretic structure of <em>L</em>-isogeny graphs. Our approaches may be put into two categories: cycles and graph cuts.</div><div>On the topic of cycles, we provide: a count for the number of cycles in the <em>L</em>-isogeny graph with cyclic kernels using traces of Brandt matrices; an efficiently computable estimate based on this approach; and a third ideal-theoretic count for a certain subclass of <em>L</em>-isogeny cycles. We provide code to compute each of these three counts.</div><div>On the topic of graph cuts, we compare several algorithms to compute graph cuts which minimise a measure called the <em>edge expansion</em>, outlining a cryptographic motivation for doing so. Our results show that a <em>greedy neighbour</em> algorithm out-performs standard spectral algorithms for computing optimal graph cuts. We provide code and study explicit examples.</div><div>Furthermore, we describe several directions of active and future research.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102768"},"PeriodicalIF":1.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737314","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}
{"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":"2026-03-01","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}
{"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":"2026-03-01","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}
{"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":"2026-03-01","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}
{"title":"Two classes of NMDS codes from Roth-Lempel codes","authors":"Zhonghao Liang, Qunying Liao","doi":"10.1016/j.ffa.2025.102779","DOIUrl":"10.1016/j.ffa.2025.102779","url":null,"abstract":"<div><div>Since near maximum distance separable (NMDS) codes have good algebraic properties and excellent error-correcting capabilities, they have been widely used in various fields such as communication systems, data storage, quantum codes, and so on. In this paper, basing on the generator matrix of Roth-Lempel codes, we present two classes of NMDS codes which generalize Han's, Zheng's and Zhou's constructions in 2023 and 2025, respectively. And we also completely determine their weight distributions.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102779"},"PeriodicalIF":1.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737315","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}
{"title":"The Rado multiplicity problem in vector spaces over finite fields","authors":"Juanjo Rué , Christoph Spiegel","doi":"10.1016/j.ffa.2025.102782","DOIUrl":"10.1016/j.ffa.2025.102782","url":null,"abstract":"<div><div>We study an analogue of the Ramsey multiplicity problem for additive structures, in particular establishing the minimum number of monochromatic 3-APs in 3-colorings of <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mn>3</mn></mrow><mrow><mi>n</mi></mrow></msubsup></math></span> as well as obtaining the first non-trivial lower bound for the minimum number of monochromatic 4-APs in 2-colorings of <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mn>5</mn></mrow><mrow><mi>n</mi></mrow></msubsup></math></span>. The former parallels results by Cumings et al. <span><span>[8]</span></span> in extremal graph theory and the latter improves upon results of Saad and Wolf <span><span>[42]</span></span>. The lower bounds are notably obtained by extending the flag algebra calculus of Razborov <span><span>[39]</span></span> to additive structures in vector spaces over finite fields.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102782"},"PeriodicalIF":1.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790235","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}