Pub Date : 2025-07-11DOI: 10.1016/j.ffa.2025.102696
Kaloyan Slavov
Let be polynomials in n variables with coefficients in a finite field . We estimate the number of points in such that each value is a nonzero square in . The error term is especially small when the define smooth projective quadrics with nonsingular intersections. We improve the error term in a recent work by Asgarli–Yip on mutual position of smooth quadrics.
{"title":"Square values of several polynomials over a finite field","authors":"Kaloyan Slavov","doi":"10.1016/j.ffa.2025.102696","DOIUrl":"10.1016/j.ffa.2025.102696","url":null,"abstract":"<div><div>Let <span><math><msub><mrow><mi>f</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>f</mi></mrow><mrow><mi>m</mi></mrow></msub></math></span> be polynomials in <em>n</em> variables with coefficients in a finite field <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span>. We estimate the number of points <span><math><munder><mrow><mi>x</mi></mrow><mo>_</mo></munder></math></span> in <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow><mrow><mi>n</mi></mrow></msubsup></math></span> such that each value <span><math><msub><mrow><mi>f</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>(</mo><munder><mrow><mi>x</mi></mrow><mo>_</mo></munder><mo>)</mo></math></span> is a nonzero square in <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span>. The error term is especially small when the <span><math><msub><mrow><mi>f</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> define smooth projective quadrics with nonsingular intersections. We improve the error term in a recent work by Asgarli–Yip on mutual position of smooth quadrics.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"109 ","pages":"Article 102696"},"PeriodicalIF":1.2,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144596553","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 : 2025-07-11DOI: 10.1016/j.ffa.2025.102697
Wenqin Zhang , Chen Yuan , Yuan Luo , Nian Li
Erasure codes can strengthen fault-tolerance and reliability in distributed storage systems. One of these, locally repairable codes (LRCs), plays a crucial role. A locally repairable code with locality r (called r-LRC) can recover any coded symbol by accessing at most r other coded symbols. The original definition of LRCs is used to repair a single failed node. To address the practical concern of multiple node failures, the concept of LRCs with locality was introduced by Prakash et al. (2012) which can be seen as a generalization of r-LRCs. Since then, the bounds and constructions of -LRCs have been extensively studied.
This paper is dedicated to both the bounds and constructions of -LRCs with disjoint local repair groups over a finite field , where the parameters r, δ, the alphabet size q, and the minimum distance d are fixed constants, while the code length n tends to infinity. Inspired by the method of the classical Gilbert-Varshamov (GV) bound, we first derive an asymptotic Gilbert-Varshamov-type bound for -LRCs in this regime. We manage to show that this GV-type bound works as a threshold for random linear -LRCs with disjoint local repair groups using the first and second moment methods. As a corollary, such a random linear -LRC has a high probability of attaining the GV-type bound. As an analogue to the classic GV-type bound, we present two constructions of -LRCs that each beats this GV-type bound. One construction is obtained from a straightforward concatenation of an outer BCH code and an inner MDS code. Another construction is based on the Kronecker product of two matrices. To complement our results, the case that n is large but finite is also considered. In this regime, we provide an explicit upper bound for the binary r-LRCs, which is an improvement over the one in Ma and Ge (2019). Furthermore, this bound is shown to be tight for some specific parameters.
{"title":"Bounds on the size of (r,δ)-locally repairable codes for fixed values q and d","authors":"Wenqin Zhang , Chen Yuan , Yuan Luo , Nian Li","doi":"10.1016/j.ffa.2025.102697","DOIUrl":"10.1016/j.ffa.2025.102697","url":null,"abstract":"<div><div>Erasure codes can strengthen fault-tolerance and reliability in distributed storage systems. One of these, locally repairable codes (LRCs), plays a crucial role. A locally repairable code with locality <em>r</em> (called <em>r</em>-LRC) can recover any coded symbol by accessing at most <em>r</em> other coded symbols. The original definition of LRCs is used to repair a single failed node. To address the practical concern of multiple node failures, the concept of LRCs with locality <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span> was introduced by Prakash et al. (2012) which can be seen as a generalization of <em>r</em>-LRCs. Since then, the bounds and constructions of <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-LRCs have been extensively studied.</div><div>This paper is dedicated to both the bounds and constructions of <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-LRCs with disjoint local repair groups over a finite field <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span>, where the parameters <em>r</em>, <em>δ</em>, the alphabet size <em>q</em>, and the minimum distance <em>d</em> are fixed constants, while the code length <em>n</em> tends to infinity. Inspired by the method of the classical Gilbert-Varshamov (GV) bound, we first derive an asymptotic Gilbert-Varshamov-type bound for <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-LRCs in this regime. We manage to show that this GV-type bound works as a threshold for random linear <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-LRCs with disjoint local repair groups using the first and second moment methods. As a corollary, such a random linear <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-LRC has a high probability of attaining the GV-type bound. As an analogue to the classic GV-type bound, we present two constructions of <span><math><mo>(</mo><mi>r</mi><mo>,</mo><mi>δ</mi><mo>)</mo></math></span>-LRCs that each beats this GV-type bound. One construction is obtained from a straightforward concatenation of an outer BCH code and an inner <span><math><mo>[</mo><mi>r</mi><mo>+</mo><mi>δ</mi><mo>−</mo><mn>1</mn><mo>,</mo><mi>r</mi><mo>]</mo></math></span> MDS code. Another construction is based on the Kronecker product of two matrices. To complement our results, the case that <em>n</em> is large but finite is also considered. In this regime, we provide an explicit upper bound for the binary <em>r</em>-LRCs, which is an improvement over the one in Ma and Ge (2019). Furthermore, this bound is shown to be tight for some specific parameters.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"109 ","pages":"Article 102697"},"PeriodicalIF":1.2,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144596550","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 : 2025-07-09DOI: 10.1016/j.ffa.2025.102694
Sha Jiang, Kangquan Li, Longjiang Qu
Permutation polynomials over finite fields have applications in many areas of mathematics and engineering. Particularly, permutation polynomials of the form have been studied for a long time. In this paper, we further investigate permutation polynomials of the form over finite fields with even characteristic. For one thing, by choosing functions with a low q-degree, we propose four classes of permutation polynomials of the form over . For the other thing, we give seven classes of permutations of the form with binomials over . Finally, we also show that the permutation polynomials constructed in this paper are not quasi-multiplicative equivalent to the known permutation polynomials.
{"title":"New constructions of permutation polynomials of the form x+γTrqq3(h(x)) over finite fields with even characteristic","authors":"Sha Jiang, Kangquan Li, Longjiang Qu","doi":"10.1016/j.ffa.2025.102694","DOIUrl":"10.1016/j.ffa.2025.102694","url":null,"abstract":"<div><div>Permutation polynomials over finite fields have applications in many areas of mathematics and engineering. Particularly, permutation polynomials of the form <span><math><mi>x</mi><mo>+</mo><mi>γ</mi><msubsup><mrow><mi>Tr</mi></mrow><mrow><mi>q</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mi>n</mi></mrow></msup></mrow></msubsup><mo>(</mo><mi>h</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>)</mo></math></span> have been studied for a long time. In this paper, we further investigate permutation polynomials of the form <span><math><mi>x</mi><mo>+</mo><mi>γ</mi><msubsup><mrow><mi>Tr</mi></mrow><mrow><mi>q</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></msubsup><mo>(</mo><mi>h</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>)</mo></math></span> over finite fields with even characteristic. For one thing, by choosing functions <span><math><mi>h</mi><mo>(</mo><mi>x</mi><mo>)</mo></math></span> with a low <em>q</em>-degree, we propose four classes of permutation polynomials of the form <span><math><mi>x</mi><mo>+</mo><mi>γ</mi><msubsup><mrow><mi>Tr</mi></mrow><mrow><mi>q</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></msubsup><mo>(</mo><mi>h</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>)</mo></math></span> over <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></msub></math></span>. For the other thing, we give seven classes of permutations of the form <span><math><mi>x</mi><mo>+</mo><msubsup><mrow><mi>Tr</mi></mrow><mrow><mi>q</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></msubsup><mo>(</mo><mi>h</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>)</mo></math></span> with binomials <span><math><mi>h</mi><mo>(</mo><mi>x</mi><mo>)</mo></math></span> over <span><math><msub><mrow><mi>F</mi></mrow><mrow><msup><mrow><mi>q</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></msub></math></span>. Finally, we also show that the permutation polynomials constructed in this paper are not quasi-multiplicative equivalent to the known permutation polynomials.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"109 ","pages":"Article 102694"},"PeriodicalIF":1.2,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144579385","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 : 2025-07-07DOI: 10.1016/j.ffa.2025.102691
Kaimin Cheng
Let q be a prime power, and let denote the finite field with q elements. Consider a positive integer n, and let be a family of subsets of . Define as the number of monic irreducible polynomials of degree n over where the coefficient of each non-leading term lies in . In this paper, we provide an asymptotic formula for , extending a result of Porritt to a more general case.
{"title":"Counting irreducible polynomials with restricted coefficients","authors":"Kaimin Cheng","doi":"10.1016/j.ffa.2025.102691","DOIUrl":"10.1016/j.ffa.2025.102691","url":null,"abstract":"<div><div>Let <em>q</em> be a prime power, and let <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> denote the finite field with <em>q</em> elements. Consider a positive integer <em>n</em>, and let <span><math><mi>R</mi><mo>=</mo><msubsup><mrow><mo>{</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>}</mo></mrow><mrow><mi>i</mi><mo>=</mo><mn>0</mn></mrow><mrow><mi>n</mi><mo>−</mo><mn>1</mn></mrow></msubsup></math></span> be a family of subsets of <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span>. Define <span><math><mi>N</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>n</mi><mo>)</mo></math></span> as the number of monic irreducible polynomials of degree <em>n</em> over <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> where the coefficient of each non-leading term <span><math><msup><mrow><mi>T</mi></mrow><mrow><mi>i</mi></mrow></msup></math></span> lies in <span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub><mo>∖</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span>. In this paper, we provide an asymptotic formula for <span><math><mi>N</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>n</mi><mo>)</mo></math></span>, extending a result of Porritt to a more general case.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"108 ","pages":"Article 102691"},"PeriodicalIF":1.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570385","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 : 2025-07-07DOI: 10.1016/j.ffa.2025.102687
Nuno Arala , Sam Chow
We establish expansion properties for suitably generic polynomials of degree d in variables over finite fields. In particular, we show that if is a polynomial of degree d, whose coefficients avoid the zero locus of some explicit polynomial of degree , and are suitably large, then . Our methods rely on a higher-degree extension of a result of Vinh on point–line incidences over a finite field.
{"title":"Expansion properties of polynomials over finite fields","authors":"Nuno Arala , Sam Chow","doi":"10.1016/j.ffa.2025.102687","DOIUrl":"10.1016/j.ffa.2025.102687","url":null,"abstract":"<div><div>We establish expansion properties for suitably generic polynomials of degree <em>d</em> in <span><math><mi>d</mi><mo>+</mo><mn>1</mn></math></span> variables over finite fields. In particular, we show that if <span><math><mi>P</mi><mo>∈</mo><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub><mo>[</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>d</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>]</mo></math></span> is a polynomial of degree <em>d</em>, whose coefficients avoid the zero locus of some explicit polynomial of degree <span><math><msub><mrow><mi>O</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>(</mo><mn>1</mn><mo>)</mo></math></span>, and <span><math><msub><mrow><mi>X</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>X</mi></mrow><mrow><mi>d</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>⊆</mo><msub><mrow><mi>F</mi></mrow><mrow><mi>q</mi></mrow></msub></math></span> are suitably large, then <span><math><mo>|</mo><mi>P</mi><mo>(</mo><msub><mrow><mi>X</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>X</mi></mrow><mrow><mi>d</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>)</mo><mo>|</mo><mo>=</mo><mi>q</mi><mo>−</mo><mi>O</mi><mo>(</mo><mn>1</mn><mo>)</mo></math></span>. Our methods rely on a higher-degree extension of a result of Vinh on point–line incidences over a finite field.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"108 ","pages":"Article 102687"},"PeriodicalIF":1.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570241","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 : 2025-07-07DOI: 10.1016/j.ffa.2025.102689
Rezhna M. Hussein, Haval M. Mohammed Salih
In this article, we provide a comprehensive classification of all primitive genus one and genus two systems of the finite group G with , where q is a prime power. Also, we use computational tools to show that G possesses no genus g group if where , and 2.
{"title":"Projective symplectic groups of genus one and two","authors":"Rezhna M. Hussein, Haval M. Mohammed Salih","doi":"10.1016/j.ffa.2025.102689","DOIUrl":"10.1016/j.ffa.2025.102689","url":null,"abstract":"<div><div>In this article, we provide a comprehensive classification of all primitive genus one and genus two systems of the finite group <em>G</em> with <span><math><mi>P</mi><mi>S</mi><mi>p</mi><mo>(</mo><mn>4</mn><mo>,</mo><mi>q</mi><mo>)</mo><mo>≤</mo><mi>G</mi><mo>≤</mo><mi>A</mi><mi>u</mi><mi>t</mi><mo>(</mo><mi>P</mi><mi>S</mi><mi>p</mi><mo>(</mo><mn>4</mn><mo>,</mo><mi>q</mi><mo>)</mo><mo>)</mo></math></span>, where <em>q</em> is a prime power. Also, we use computational tools to show that <em>G</em> possesses no genus <em>g</em> group if <span><math><mi>q</mi><mo>></mo><mn>5</mn></math></span> where <span><math><mi>g</mi><mo>=</mo><mn>1</mn></math></span>, and 2.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"108 ","pages":"Article 102689"},"PeriodicalIF":1.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144569057","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 : 2025-07-07DOI: 10.1016/j.ffa.2025.102686
Rajendra Prasad Rajpurohit, Maheshanand Bhaintwal
In this paper, we present a novel construction of maximally recoverable codes with two-level hierarchical locality using a parity-check matrix approach. The construction given in this paper utilizes Gabidulin codes for mid-level heavy parities and linearized Reed-Solomon codes for global heavy parities. When the number of local sets is small, this construction performs better than the previously known constructions as the field size required in our construction is smaller for such cases, making it useful for practical scenarios in distributed data storage systems. We also consider a special case of our construction when the number of global parities is fixed and is equal to 1. In this case, our construction performs better when the number of local sets is small and the number of mid-level parities is even.
{"title":"A new construction of maximally recoverable codes with hierarchical locality","authors":"Rajendra Prasad Rajpurohit, Maheshanand Bhaintwal","doi":"10.1016/j.ffa.2025.102686","DOIUrl":"10.1016/j.ffa.2025.102686","url":null,"abstract":"<div><div>In this paper, we present a novel construction of maximally recoverable codes with two-level hierarchical locality using a parity-check matrix approach. The construction given in this paper utilizes Gabidulin codes for mid-level heavy parities and linearized Reed-Solomon codes for global heavy parities. When the number of local sets is small, this construction performs better than the previously known constructions as the field size required in our construction is smaller for such cases, making it useful for practical scenarios in distributed data storage systems. We also consider a special case of our construction when the number of global parities is fixed and is equal to 1. In this case, our construction performs better when the number of local sets is small and the number of mid-level parities is even.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"109 ","pages":"Article 102686"},"PeriodicalIF":1.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570348","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 : 2025-07-07DOI: 10.1016/j.ffa.2025.102693
Joachim König
Many interesting questions in arithmetic dynamics revolve, in one way or another, around the (local and/or global) reducibility behavior of iterates of a polynomial. We show that for very general families of integer polynomials f (and, more generally, rational functions over number fields), the set of stable primes, i.e., primes modulo which all iterates of f are irreducible, is a density zero set. Compared to previous results, our families cover a much wider ground, and in particular apply to 100% of polynomials of any given odd degree, thus adding evidence to the conjecture that polynomials with a “large” set of stable primes are necessarily of a very specific shape, and in particular are necessarily postcritically finite.
{"title":"On the set of stable primes for postcritically infinite maps over number fields","authors":"Joachim König","doi":"10.1016/j.ffa.2025.102693","DOIUrl":"10.1016/j.ffa.2025.102693","url":null,"abstract":"<div><div>Many interesting questions in arithmetic dynamics revolve, in one way or another, around the (local and/or global) reducibility behavior of iterates of a polynomial. We show that for very general families of integer polynomials <em>f</em> (and, more generally, rational functions over number fields), the set of stable primes, i.e., primes modulo which all iterates of <em>f</em> are irreducible, is a density zero set. Compared to previous results, our families cover a much wider ground, and in particular apply to 100% of polynomials of any given odd degree, thus adding evidence to the conjecture that polynomials with a “large” set of stable primes are necessarily of a very specific shape, and in particular are necessarily postcritically finite.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"108 ","pages":"Article 102693"},"PeriodicalIF":1.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570240","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 : 2025-07-07DOI: 10.1016/j.ffa.2025.102688
Marilena Crupi , Antonino Ficarra
Blocking semiovals and the determination of their (minimum) sizes constitute one of the central research topics in finite projective geometry. In this article we introduce the concept of blocking set with the -property in a finite projective plane , with a line of and q a prime power. This notion greatly generalizes that of blocking semioval. We address the question of determining those integers k for which there exists a blocking set of size k with the -property. To solve this problem, we build new theory which deeply analyzes the interplay between blocking sets in finite projective and affine planes.
{"title":"Generalizing blocking semiovals in finite projective planes","authors":"Marilena Crupi , Antonino Ficarra","doi":"10.1016/j.ffa.2025.102688","DOIUrl":"10.1016/j.ffa.2025.102688","url":null,"abstract":"<div><div>Blocking semiovals and the determination of their (minimum) sizes constitute one of the central research topics in finite projective geometry. In this article we introduce the concept of blocking set with the <span><math><msub><mrow><mi>r</mi></mrow><mrow><mo>∞</mo></mrow></msub></math></span>-property in a finite projective plane <span><math><mtext>PG</mtext><mo>(</mo><mn>2</mn><mo>,</mo><mi>q</mi><mo>)</mo></math></span>, with <span><math><msub><mrow><mi>r</mi></mrow><mrow><mo>∞</mo></mrow></msub></math></span> a line of <span><math><mtext>PG</mtext><mo>(</mo><mn>2</mn><mo>,</mo><mi>q</mi><mo>)</mo></math></span> and <em>q</em> a prime power. This notion greatly generalizes that of blocking semioval. We address the question of determining those integers <em>k</em> for which there exists a blocking set of size <em>k</em> with the <span><math><msub><mrow><mi>r</mi></mrow><mrow><mo>∞</mo></mrow></msub></math></span>-property. To solve this problem, we build new theory which deeply analyzes the interplay between blocking sets in finite projective and affine planes.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"108 ","pages":"Article 102688"},"PeriodicalIF":1.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570245","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 : 2025-07-07DOI: 10.1016/j.ffa.2025.102692
C. Martínez, F. Molina, A. Piñera-Nicolás
Group codes are linear codes that can be identified with (two-sided) ideals of a group algebra . Assuming that is semisimple, we use its decomposition as the direct sum of two ideals, one of them the group code, to design two decoding algorithms. The first one generalizes Meggitt's algorithm designed for cyclic codes, while the other one is inspired in the decoding algorithm studied in [10] and aims to improve it.
{"title":"Decoding algorithms in group codes","authors":"C. Martínez, F. Molina, A. Piñera-Nicolás","doi":"10.1016/j.ffa.2025.102692","DOIUrl":"10.1016/j.ffa.2025.102692","url":null,"abstract":"<div><div>Group codes are linear codes that can be identified with (two-sided) ideals of a group algebra <span><math><mi>K</mi><mi>G</mi></math></span>. Assuming that <span><math><mi>K</mi><mi>G</mi></math></span> is semisimple, we use its decomposition as the direct sum of two ideals, one of them the group code, to design two decoding algorithms. The first one generalizes Meggitt's algorithm designed for cyclic codes, while the other one is inspired in the decoding algorithm studied in <span><span>[10]</span></span> and aims to improve it.</div></div>","PeriodicalId":50446,"journal":{"name":"Finite Fields and Their Applications","volume":"108 ","pages":"Article 102692"},"PeriodicalIF":1.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570386","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}