Pub Date : 2026-01-13DOI: 10.1016/j.ffa.2025.102789
Lavanya G, Anuradha Sharma
<div><div>Let <em>q</em> be a prime power, and let <em>m</em>, <em>v</em>, <em>t</em> be integers satisfying <span><math><mn>2</mn><mo>≤</mo><mi>t</mi><mo><</mo><mi>v</mi><mo>≤</mo><mi>m</mi></math></span> and <span><math><msup><mrow><mi>q</mi></mrow><mrow><mi>m</mi><mo>−</mo><mi>t</mi></mrow></msup><mo>></mo><mrow><mo>(</mo><mtable><mtr><mtd><mi>v</mi></mtd></mtr><mtr><mtd><mi>t</mi></mtd></mtr></mtable><mo>)</mo></mrow><mo>≥</mo><mn>3</mn></math></span>, where <span><math><mo>(</mo><mtable><mtr><mtd><mo>⋅</mo></mtd></mtr><mtr><mtd><mo>⋅</mo></mtd></mtr></mtable><mo>)</mo></math></span> denotes the binomial coefficient. Let <em>X</em> be a subset of <span><math><mo>{</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>…</mo><mo>,</mo><mi>m</mi><mo>}</mo></math></span> with <span><math><mo>|</mo><mi>X</mi><mo>|</mo><mo>=</mo><mi>v</mi></math></span>. In this paper, we consider the set <span><math><mi>Δ</mi><mo>=</mo><mo>{</mo><mi>u</mi><mo>∈</mo><msubsup><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow><mrow><mi>m</mi></mrow></msubsup><mo>:</mo><mtext>supp</mtext><mo>(</mo><mi>u</mi><mo>)</mo><mo>⊆</mo><mi>X</mi><mtext> and </mtext><mi>w</mi><mo>(</mo><mi>u</mi><mo>)</mo><mo>≤</mo><mi>t</mi><mo>}</mo></math></span>, where <span><math><mtext>supp</mtext><mo>(</mo><mo>⋅</mo><mo>)</mo></math></span> denotes the support of a vector and <span><math><mi>w</mi><mo>(</mo><mo>⋅</mo><mo>)</mo></math></span> denotes the Hamming weight function. We first observe that the set Δ is a simplicial complex of <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow><mrow><mi>m</mi></mrow></msubsup></math></span> with support <span><math><mi>A</mi><mo>=</mo><mo>{</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>A</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>}</mo></math></span> consisting of all distinct subsets of <em>X</em> with cardinality <em>t</em>. Note that <span><math><mi>b</mi><mo>=</mo><mrow><mo>(</mo><mtable><mtr><mtd><mi>v</mi></mtd></mtr><mtr><mtd><mi>t</mi></mtd></mtr></mtable><mo>)</mo></mrow><mo>≥</mo><mn>3</mn></math></span>, <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>∖</mo><mo>(</mo><munder><mo>⋃</mo><mrow><mn>1</mn><mo>≤</mo><mi>j</mi><mo>(</mo><mo>≠</mo><mi>i</mi><mo>)</mo><mo>≤</mo><mi>b</mi></mrow></munder><msub><mrow><mi>A</mi></mrow><mrow><mi>j</mi></mrow></msub><mo>)</mo><mo>=</mo><mo>∅</mo></math></span> for <span><math><mn>1</mn><mo>≤</mo><mi>i</mi><mo>≤</mo><mi>b</mi></math></span>, and the pair <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>A</mi><mo>)</mo></math></span> forms a trivial Steiner system. In this paper, we study linear codes over <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> with defining sets <span><math><msup><mrow><mi>Δ</mi></mrow><mrow><mi>c</mi></mrow></msup><mo>=</mo><msubsup><mrow><mi>F</mi></mrow><mrow><mi>q</
{"title":"Construction of several infinite families of linear codes with new parameters: Hamming weight enumerators and hull dimensions","authors":"Lavanya G, Anuradha Sharma","doi":"10.1016/j.ffa.2025.102789","DOIUrl":"10.1016/j.ffa.2025.102789","url":null,"abstract":"<div><div>Let <em>q</em> be a prime power, and let <em>m</em>, <em>v</em>, <em>t</em> be integers satisfying <span><math><mn>2</mn><mo>≤</mo><mi>t</mi><mo><</mo><mi>v</mi><mo>≤</mo><mi>m</mi></math></span> and <span><math><msup><mrow><mi>q</mi></mrow><mrow><mi>m</mi><mo>−</mo><mi>t</mi></mrow></msup><mo>></mo><mrow><mo>(</mo><mtable><mtr><mtd><mi>v</mi></mtd></mtr><mtr><mtd><mi>t</mi></mtd></mtr></mtable><mo>)</mo></mrow><mo>≥</mo><mn>3</mn></math></span>, where <span><math><mo>(</mo><mtable><mtr><mtd><mo>⋅</mo></mtd></mtr><mtr><mtd><mo>⋅</mo></mtd></mtr></mtable><mo>)</mo></math></span> denotes the binomial coefficient. Let <em>X</em> be a subset of <span><math><mo>{</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>…</mo><mo>,</mo><mi>m</mi><mo>}</mo></math></span> with <span><math><mo>|</mo><mi>X</mi><mo>|</mo><mo>=</mo><mi>v</mi></math></span>. In this paper, we consider the set <span><math><mi>Δ</mi><mo>=</mo><mo>{</mo><mi>u</mi><mo>∈</mo><msubsup><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow><mrow><mi>m</mi></mrow></msubsup><mo>:</mo><mtext>supp</mtext><mo>(</mo><mi>u</mi><mo>)</mo><mo>⊆</mo><mi>X</mi><mtext> and </mtext><mi>w</mi><mo>(</mo><mi>u</mi><mo>)</mo><mo>≤</mo><mi>t</mi><mo>}</mo></math></span>, where <span><math><mtext>supp</mtext><mo>(</mo><mo>⋅</mo><mo>)</mo></math></span> denotes the support of a vector and <span><math><mi>w</mi><mo>(</mo><mo>⋅</mo><mo>)</mo></math></span> denotes the Hamming weight function. We first observe that the set Δ is a simplicial complex of <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow><mrow><mi>m</mi></mrow></msubsup></math></span> with support <span><math><mi>A</mi><mo>=</mo><mo>{</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>A</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>}</mo></math></span> consisting of all distinct subsets of <em>X</em> with cardinality <em>t</em>. Note that <span><math><mi>b</mi><mo>=</mo><mrow><mo>(</mo><mtable><mtr><mtd><mi>v</mi></mtd></mtr><mtr><mtd><mi>t</mi></mtd></mtr></mtable><mo>)</mo></mrow><mo>≥</mo><mn>3</mn></math></span>, <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>∖</mo><mo>(</mo><munder><mo>⋃</mo><mrow><mn>1</mn><mo>≤</mo><mi>j</mi><mo>(</mo><mo>≠</mo><mi>i</mi><mo>)</mo><mo>≤</mo><mi>b</mi></mrow></munder><msub><mrow><mi>A</mi></mrow><mrow><mi>j</mi></mrow></msub><mo>)</mo><mo>=</mo><mo>∅</mo></math></span> for <span><math><mn>1</mn><mo>≤</mo><mi>i</mi><mo>≤</mo><mi>b</mi></math></span>, and the pair <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>A</mi><mo>)</mo></math></span> forms a trivial Steiner system. In this paper, we study linear codes over <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> with defining sets <span><math><msup><mrow><mi>Δ</mi></mrow><mrow><mi>c</mi></mrow></msup><mo>=</mo><msubsup><mrow><mi>F</mi></mrow><mrow><mi>q</","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"112 ","pages":"Article 102789"},"PeriodicalIF":1.2,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981219","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 : 2026-01-02DOI: 10.1016/j.ffa.2025.102787
Wei Tang , Yue Zhou
Let denote the set of symmetric bilinear forms over an n-dimensional -vector space. A subset of is called a d-code if the rank of is larger than or equal to d for any distinct A and B in . If is further closed under matrix addition, then is sharply upper bounded by if is even and if is odd. Additive codes meeting these upper bounds are called maximum. There are very few known constructions of them. In this paper, we obtain a new family of maximum -linear -codes in for and 10 which are not equivalent to any known constructions. Furthermore, we completely determine the equivalence between distinct members in this new family.
{"title":"A new family of maximum linear symmetric rank-distance codes","authors":"Wei Tang , Yue Zhou","doi":"10.1016/j.ffa.2025.102787","DOIUrl":"10.1016/j.ffa.2025.102787","url":null,"abstract":"<div><div>Let <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>(</mo><mi>q</mi><mo>)</mo></math></span> denote the set of symmetric bilinear forms over an <em>n</em>-dimensional <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span>-vector space. A subset <span><math><mi>C</mi></math></span> of <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>(</mo><mi>q</mi><mo>)</mo></math></span> is called a <em>d</em>-code if the rank of <span><math><mi>A</mi><mo>−</mo><mi>B</mi></math></span> is larger than or equal to <em>d</em> for any distinct <em>A</em> and <em>B</em> in <span><math><mi>C</mi></math></span>. If <span><math><mi>C</mi></math></span> is further closed under matrix addition, then <span><math><mo>|</mo><mi>C</mi><mo>|</mo></math></span> is sharply upper bounded by <span><math><msup><mrow><mi>q</mi></mrow><mrow><mi>n</mi><mo>(</mo><mi>n</mi><mo>−</mo><mi>d</mi><mo>+</mo><mn>2</mn><mo>)</mo><mo>/</mo><mn>2</mn></mrow></msup></math></span> if <span><math><mi>n</mi><mo>−</mo><mi>d</mi></math></span> is even and <span><math><msup><mrow><mi>q</mi></mrow><mrow><mo>(</mo><mi>n</mi><mo>+</mo><mn>1</mn><mo>)</mo><mo>(</mo><mi>n</mi><mo>−</mo><mi>d</mi><mo>+</mo><mn>1</mn><mo>)</mo><mo>/</mo><mn>2</mn></mrow></msup></math></span> if <span><math><mi>n</mi><mo>−</mo><mi>d</mi></math></span> is odd. Additive codes meeting these upper bounds are called maximum. There are very few known constructions of them. In this paper, we obtain a new family of maximum <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span>-linear <span><math><mo>(</mo><mi>n</mi><mo>−</mo><mn>2</mn><mo>)</mo></math></span>-codes in <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>(</mo><mi>q</mi><mo>)</mo></math></span> for <span><math><mi>n</mi><mo>=</mo><mn>6</mn><mo>,</mo><mn>8</mn></math></span> and 10 which are not equivalent to any known constructions. Furthermore, we completely determine the equivalence between distinct members in this new family.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102787"},"PeriodicalIF":1.2,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883540","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 : 2025-12-30DOI: 10.1016/j.ffa.2025.102788
Usman Mushrraf, Ferdinando Zullo
One-weight codes, in which all nonzero codewords share the same weight, form a highly structured class of linear codes with deep connections to finite geometry. While their classification is well understood in the Hamming and rank metrics—being equivalent to (direct sums of) simplex codes—the sum-rank metric presents a far more intricate landscape. In this work, we explore the geometry of one-weight sum-rank metric codes, focusing on three distinct classes. First, we introduce and classify constant rank-list sum-rank metric codes, where each nonzero codeword has the same tuple of ranks, extending results from the rank-metric setting. Next, we investigate the more general constant rank-profile codes, where, up to reordering, each nonzero codeword has the same tuple of ranks. Although a complete classification remains elusive, we present the first examples and partial structural results for this class. Finally, we consider one-weight codes that are also MSRD (Maximum Sum-Rank Distance) codes. For dimension two, constructions arise from partitions of scattered linear sets on projective lines. For dimension three, we connect their existence to that of special 2-fold blocking sets in the projective plane, leading to new bounds and nonexistence results over certain fields.
{"title":"One-weight codes in the sum-rank metric","authors":"Usman Mushrraf, Ferdinando Zullo","doi":"10.1016/j.ffa.2025.102788","DOIUrl":"10.1016/j.ffa.2025.102788","url":null,"abstract":"<div><div>One-weight codes, in which all nonzero codewords share the same weight, form a highly structured class of linear codes with deep connections to finite geometry. While their classification is well understood in the Hamming and rank metrics—being equivalent to (direct sums of) simplex codes—the sum-rank metric presents a far more intricate landscape. In this work, we explore the geometry of one-weight sum-rank metric codes, focusing on three distinct classes. First, we introduce and classify <em>constant rank-list</em> sum-rank metric codes, where each nonzero codeword has the same tuple of ranks, extending results from the rank-metric setting. Next, we investigate the more general <em>constant rank-profile</em> codes, where, up to reordering, each nonzero codeword has the same tuple of ranks. Although a complete classification remains elusive, we present the first examples and partial structural results for this class. Finally, we consider one-weight codes that are also MSRD (Maximum Sum-Rank Distance) codes. For dimension two, constructions arise from partitions of scattered linear sets on projective lines. For dimension three, we connect their existence to that of special 2-fold blocking sets in the projective plane, leading to new bounds and nonexistence results over certain fields.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102788"},"PeriodicalIF":1.2,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883542","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 : 2025-12-30DOI: 10.1016/j.ffa.2025.102786
Xiaoran Wang, Junling Zhou
This paper concentrates on constructing infinite families of non-simple subspace 2-designs and 3-designs with block dimension 4. We investigate in detail the structure of the -incidence matrix between 2-subspaces and 4-subspaces of with . Employing the incidence matrix, we establish two recursive constructions for 2- designs, which are based on a 2- design and a 2- design, respectively. Several new infinite classes of simple q-analogs of group divisible designs (q-GDDs) with block dimension 4 are also produced. Making use of the recursive constructions and new q-GDDs, plenty of new infinite series of non-simple subspace 2-designs with block dimension 4 are constructed. We also study the -incidence matrix between 3-subspaces and 4-subspaces. From this, a recursive construction and a new infinite family of non-simple 3- designs are produced as well.
{"title":"Infinite families of non-simple subspace 2- and 3-designs with block dimension 4","authors":"Xiaoran Wang, Junling Zhou","doi":"10.1016/j.ffa.2025.102786","DOIUrl":"10.1016/j.ffa.2025.102786","url":null,"abstract":"<div><div>This paper concentrates on constructing infinite families of non-simple subspace 2-designs and 3-designs with block dimension 4. We investigate in detail the structure of the <span><math><mrow><mi>GL</mi></mrow><mo>(</mo><mi>m</mi><mo>,</mo><msup><mrow><mi>q</mi></mrow><mrow><mi>l</mi></mrow></msup><mo>)</mo></math></span>-incidence matrix between 2-subspaces and 4-subspaces of <span><math><mi>GF</mi><mspace></mspace><msup><mrow><mo>(</mo><mi>q</mi><mo>)</mo></mrow><mrow><mi>m</mi><mi>l</mi></mrow></msup></math></span> with <span><math><mi>m</mi><mo>,</mo><mi>l</mi><mo>≥</mo><mn>3</mn></math></span>. Employing the incidence matrix, we establish two recursive constructions for 2-<span><math><msub><mrow><mo>(</mo><mi>m</mi><mi>l</mi><mo>,</mo><mn>4</mn><mo>,</mo><mi>λ</mi><mo>)</mo></mrow><mrow><mi>q</mi></mrow></msub></math></span> designs, which are based on a 2-<span><math><msub><mrow><mo>(</mo><mi>l</mi><mo>,</mo><mn>4</mn><mo>,</mo><mi>λ</mi><mo>)</mo></mrow><mrow><mi>q</mi></mrow></msub></math></span> design and a 2-<span><math><msub><mrow><mo>(</mo><mi>l</mi><mo>,</mo><mn>3</mn><mo>,</mo><mi>μ</mi><mo>)</mo></mrow><mrow><mi>q</mi></mrow></msub></math></span> design, respectively. Several new infinite classes of simple <em>q</em>-analogs of group divisible designs (<em>q</em>-GDDs) with block dimension 4 are also produced. Making use of the recursive constructions and new <em>q</em>-GDDs, plenty of new infinite series of non-simple subspace 2-designs with block dimension 4 are constructed. We also study the <span><math><mi>GL</mi><mo>(</mo><mi>m</mi><mo>,</mo><msup><mrow><mi>q</mi></mrow><mrow><mi>l</mi></mrow></msup><mo>)</mo></math></span>-incidence matrix between 3-subspaces and 4-subspaces. From this, a recursive construction and a new infinite family of non-simple 3-<span><math><msub><mrow><mo>(</mo><mi>m</mi><mi>l</mi><mo>,</mo><mn>4</mn><mo>,</mo><mi>λ</mi><mo>)</mo></mrow><mrow><mi>q</mi></mrow></msub></math></span> designs are produced as well.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102786"},"PeriodicalIF":1.2,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883539","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 : 2025-12-30DOI: 10.1016/j.ffa.2025.102785
Carlos Galindo , Fernando Hernando , Helena Martín-Cruz , Ryutaroh Matsumoto
Classical -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 -locally recoverable codes which are quantum error-correcting codes capable of correcting qudit erasures from sets of at most qudits.
We give a necessary and sufficient condition for a quantum stabilizer code to be -locally recoverable. Our condition depends only on the puncturing and shortening at suitable sets of both the symplectic self-orthogonal code C used for constructing and its symplectic dual . When 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 -local recoverability. A Singleton-like bound is stated in this case and examples attaining the bound are given.
{"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":"2025-12-30","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}
Pub Date : 2025-12-17DOI: 10.1016/j.ffa.2025.102783
Chenying Lin , Gilles Zémor
A k-wise ℓ-divisible set family is a collection of subsets of such that any intersection of k sets in has cardinality divisible by ℓ. If , it is well-known that . We generalise this by proving that if , for any prime number p.
For arbitrary values of ℓ, we prove that -wise ℓ-divisible set families satisfy and that the only families achieving the upper bound are atomic, meaning that they consist of all the unions of disjoint subsets of size ℓ. This improves upon a recent result by Gishboliner, Sudakov and Timon, that arrived at the same conclusion for k-wise ℓ-divisible families, with values of k that behave exponentially in ℓ.
Our techniques rely heavily upon a coding-theory analogue of Kneser's Theorem from additive combinatorics.
一个向k可整除的集合族是{1,…,n}的子集的集合F,使得F中k个集合的任何交集都具有可被r整除的基数。若k= n =2,则已知|F|≤2⌊n/2⌋。我们通过证明|F|≤2⌊n/p⌋,如果k= r =p,对于任意素数p,我们证明了4个2 ~ 2可分集合族F满足|F|≤2⌊n/p⌋,并且唯一达到上限的族是原子族,这意味着它们由大小为r的不相交子集的所有并组成。这改进了Gishboliner, Sudakov和Timon最近的一个结果,他们对k-可分族得出了相同的结论,其中k的值在r中表现为指数。我们的技术在很大程度上依赖于可加组合学中克尼泽定理的编码理论类比。
{"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":"2025-12-17","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}
Pub Date : 2025-12-17DOI: 10.1016/j.ffa.2025.102782
Juanjo Rué , Christoph Spiegel
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 as well as obtaining the first non-trivial lower bound for the minimum number of monochromatic 4-APs in 2-colorings of . The former parallels results by Cumings et al. [8] in extremal graph theory and the latter improves upon results of Saad and Wolf [42]. The lower bounds are notably obtained by extending the flag algebra calculus of Razborov [39] to additive structures in vector spaces over finite fields.
我们研究了可加性结构Ramsey多重性问题的一个类似问题,特别是建立了F3n的3-着色中单色3- ap的最小数目,以及F5n的2-着色中单色4- ap的最小数目的第一个非平凡下界。前者与Cumings et al.[8]在极值图论中的结果相似,后者改进了Saad和Wolf[8]的结果。将Razborov[39]的标志代数演算推广到有限域上向量空间的加性结构,得到了下界。
{"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":"2025-12-17","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}
Pub Date : 2025-12-16DOI: 10.1016/j.ffa.2025.102780
H. Navarro, Luz A. Pérez
In this paper, we present two methods for constructing curves of Kummer type with many rational points over finite fields. The first method is based on binomials, while the second employs reciprocal polynomials. The latter is an extension of the method introduced by Gupta et al. (2023) [19] over quadratic finite fields, to non-prime finite fields. As a result, we found 63 new records and 37 new entries for the online table of curves with many points found at manYPoints.
{"title":"New curves of Kummer type with many rational points over finite fields","authors":"H. Navarro, Luz A. Pérez","doi":"10.1016/j.ffa.2025.102780","DOIUrl":"10.1016/j.ffa.2025.102780","url":null,"abstract":"<div><div>In this paper, we present two methods for constructing curves of Kummer type with many rational points over finite fields. The first method is based on binomials, while the second employs reciprocal polynomials. The latter is an extension of the method introduced by Gupta et al. (2023) <span><span>[19]</span></span> over quadratic finite fields, to non-prime finite fields. As a result, we found 63 new records and 37 new entries for the online table of curves with many points found at <span><span>manYPoints</span><svg><path></path></svg></span>.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102780"},"PeriodicalIF":1.2,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789554","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 : 2025-12-15DOI: 10.1016/j.ffa.2025.102784
Mariusz Kwiatkowski, Mark Pankov, Adam Tyc
Consider the point-line geometry whose maximal singular subspaces correspond to q-ary simplex codes of dimension k. Maximal cliques in the collinearity graph of this geometry contain no more than elements and maximal singular subspaces of are n-cliques of this graph. If , then and there is a one-to-one correspondence between -cliques of the collinearity graph and symmetric -designs. For the case when we construct a class of n-cliques distinct from maximal singular subspaces. In the case when , some of these cliques are normal rational curves.
{"title":"One class of maximal cliques in the collinearity graphs of geometries related to simplex codes","authors":"Mariusz Kwiatkowski, Mark Pankov, Adam Tyc","doi":"10.1016/j.ffa.2025.102784","DOIUrl":"10.1016/j.ffa.2025.102784","url":null,"abstract":"<div><div>Consider the point-line geometry <span><math><mi>S</mi><mo>(</mo><mi>k</mi><mo>,</mo><mi>q</mi><mo>)</mo></math></span> whose maximal singular subspaces correspond to <em>q</em>-ary simplex codes of dimension <em>k</em>. Maximal cliques in the collinearity graph of this geometry contain no more than <span><math><mi>n</mi><mo>=</mo><mo>(</mo><msup><mrow><mi>q</mi></mrow><mrow><mi>k</mi></mrow></msup><mo>−</mo><mn>1</mn><mo>)</mo><mo>/</mo><mo>(</mo><mi>q</mi><mo>−</mo><mn>1</mn><mo>)</mo></math></span> elements and maximal singular subspaces of <span><math><mi>S</mi><mo>(</mo><mi>k</mi><mo>,</mo><mi>q</mi><mo>)</mo></math></span> are <em>n</em>-cliques of this graph. If <span><math><mi>q</mi><mo>=</mo><mn>2</mn></math></span>, then <span><math><mi>n</mi><mo>=</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>k</mi></mrow></msup><mo>−</mo><mn>1</mn></math></span> and there is a one-to-one correspondence between <span><math><mo>(</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>k</mi></mrow></msup><mo>−</mo><mn>1</mn><mo>)</mo></math></span>-cliques of the collinearity graph and symmetric <span><math><mo>(</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>k</mi></mrow></msup><mo>−</mo><mn>1</mn><mo>,</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>k</mi><mo>−</mo><mn>1</mn></mrow></msup><mo>,</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>k</mi><mo>−</mo><mn>2</mn></mrow></msup><mo>)</mo></math></span>-designs. For the case when <span><math><mi>q</mi><mo>≥</mo><mn>5</mn></math></span> we construct a class of <em>n</em>-cliques distinct from maximal singular subspaces. In the case when <span><math><mi>k</mi><mo>=</mo><mn>2</mn></math></span>, some of these cliques are normal rational curves.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102784"},"PeriodicalIF":1.2,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789556","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 : 2025-12-15DOI: 10.1016/j.ffa.2025.102778
Yajing Zhou , Rongquan Feng
Let be the ring of residue classes modulo n, and let be the group of its units. In 2017, Mollahajiaghaei presented a formula for the number of solutions of the congruence . This paper considers the addition of squares and cubes over . Specifically, when n is a prime number such that , we correct the formula given by Mollahajiaghaei.
{"title":"On the addition of squares and cubes of units modulo n","authors":"Yajing Zhou , Rongquan Feng","doi":"10.1016/j.ffa.2025.102778","DOIUrl":"10.1016/j.ffa.2025.102778","url":null,"abstract":"<div><div>Let <span><math><msub><mrow><mi>Z</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span> be the ring of residue classes modulo <em>n</em>, and let <span><math><msubsup><mrow><mi>Z</mi></mrow><mrow><mi>n</mi></mrow><mrow><mo>⁎</mo></mrow></msubsup></math></span> be the group of its units. In 2017, Mollahajiaghaei presented a formula for the number of solutions <span><math><mo>(</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>)</mo><mo>∈</mo><msup><mrow><mo>(</mo><msubsup><mrow><mi>Z</mi></mrow><mrow><mi>n</mi></mrow><mrow><mo>⁎</mo></mrow></msubsup><mo>)</mo></mrow><mrow><mi>k</mi></mrow></msup></math></span> of the congruence <span><math><msubsup><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>+</mo><mo>⋯</mo><mo>+</mo><msubsup><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>≡</mo><mi>c</mi><mspace></mspace><mo>(</mo><mrow><mi>mod</mi></mrow><mspace></mspace><mi>n</mi><mo>)</mo></math></span>. This paper considers the addition of squares and cubes over <span><math><msubsup><mrow><mi>Z</mi></mrow><mrow><mi>n</mi></mrow><mrow><mo>⁎</mo></mrow></msubsup></math></span>. Specifically, when <em>n</em> is a prime number such that <span><math><mi>n</mi><mo>≡</mo><mn>1</mn><mspace></mspace><mo>(</mo><mrow><mi>mod</mi></mrow><mspace></mspace><mn>4</mn><mo>)</mo></math></span>, we correct the formula given by Mollahajiaghaei.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"111 ","pages":"Article 102778"},"PeriodicalIF":1.2,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789555","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}