{"title":"Block-Primitive Rank 3 \n \n \n \n t\n \n \n -Designs With Sporadic or Alternating Socle","authors":"Suyun Ding, Xiaoqin Zhan","doi":"10.1002/jcd.70034","DOIUrl":null,"url":null,"abstract":"<div>\n \n <p>In this paper, we classify nontrivial <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>t</mi>\n </mrow>\n </mrow>\n </semantics></math>-<span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mrow>\n <mo>(</mo>\n \n <mrow>\n <mi>v</mi>\n \n <mo>,</mo>\n \n <mi>k</mi>\n \n <mo>,</mo>\n \n <mi>λ</mi>\n </mrow>\n \n <mo>)</mo>\n </mrow>\n </mrow>\n </mrow>\n </semantics></math> designs with <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>t</mi>\n \n <mo>≥</mo>\n \n <mn>2</mn>\n </mrow>\n </mrow>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>v</mi>\n \n <mo>≥</mo>\n \n <mn>2</mn>\n \n <mi>k</mi>\n </mrow>\n </mrow>\n </semantics></math> admitting an automorphism group that acts primitively with rank 3 on the block set, under the assumption that the socle is a sporadic simple group or an alternating group. We show that, apart from the known symmetric examples, the only possibilities are the 2-, 3-, and 4-designs associated with the Mathieu groups <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mi>M</mi>\n \n <mn>22</mn>\n </msub>\n </mrow>\n </mrow>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mi>M</mi>\n \n <mn>23</mn>\n </msub>\n </mrow>\n </mrow>\n </semantics></math>, together with a small number of 2-designs on <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>v</mi>\n \n <mo>∈</mo>\n \n <mrow>\n <mo>{</mo>\n \n <mrow>\n <mn>6</mn>\n \n <mo>,</mo>\n \n <mn>10</mn>\n \n <mo>,</mo>\n \n <mn>15</mn>\n </mrow>\n \n <mo>}</mo>\n </mrow>\n </mrow>\n </mrow>\n </semantics></math> points arising from alternating groups.</p>\n </div>","PeriodicalId":15389,"journal":{"name":"Journal of Combinatorial Designs","volume":"34 12","pages":"555-568"},"PeriodicalIF":0.8000,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Combinatorial Designs","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/jcd.70034","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2026/9/6 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
In this paper, we classify nontrivial - designs with and admitting an automorphism group that acts primitively with rank 3 on the block set, under the assumption that the socle is a sporadic simple group or an alternating group. We show that, apart from the known symmetric examples, the only possibilities are the 2-, 3-, and 4-designs associated with the Mathieu groups and , together with a small number of 2-designs on points arising from alternating groups.
期刊介绍:
The Journal of Combinatorial Designs is an international journal devoted to the timely publication of the most influential papers in the area of combinatorial design theory. All topics in design theory, and in which design theory has important applications, are covered, including:
block designs, t-designs, pairwise balanced designs and group divisible designs
Latin squares, quasigroups, and related algebras
computational methods in design theory
construction methods
applications in computer science, experimental design theory, and coding theory
graph decompositions, factorizations, and design-theoretic techniques in graph theory and extremal combinatorics
finite geometry and its relation with design theory.
algebraic aspects of design theory.
Researchers and scientists can depend on the Journal of Combinatorial Designs for the most recent developments in this rapidly growing field, and to provide a forum for both theoretical research and applications. All papers appearing in the Journal of Combinatorial Designs are carefully peer refereed.