{"title":"交替子群中下降和超越枚举数的同步性","authors":"Umesh Shankar","doi":"10.1016/j.disc.2025.114521","DOIUrl":null,"url":null,"abstract":"<div><div>Generalising the work of Dey <span><span>[2]</span></span>, we define the notion of ultra-synchronicity of sequences of real numbers. Let <span><math><msub><mrow><mi>B</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub><mo>,</mo><msub><mrow><mi>C</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub><mo>,</mo><msub><mrow><mi>P</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub><mo>,</mo><msub><mrow><mi>Q</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> be the number of even permutations of <span><math><mo>[</mo><mi>n</mi><mo>]</mo></math></span> with <em>k</em> descents, odd permutations with <em>k</em> descents, even permutations with <em>k</em> excedances and odd permutations with <em>k</em> excedances, respectively. We show that the four sequences are ultra-synchronised for all <span><math><mi>n</mi><mo>≥</mo><mn>5</mn></math></span>. This proves a strengthening of two conjectures of Dey <span><span>[2]</span></span>.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"348 8","pages":"Article 114521"},"PeriodicalIF":0.7000,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Synchronicity of descent and excedance enumerators in the alternating subgroup\",\"authors\":\"Umesh Shankar\",\"doi\":\"10.1016/j.disc.2025.114521\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Generalising the work of Dey <span><span>[2]</span></span>, we define the notion of ultra-synchronicity of sequences of real numbers. Let <span><math><msub><mrow><mi>B</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub><mo>,</mo><msub><mrow><mi>C</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub><mo>,</mo><msub><mrow><mi>P</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub><mo>,</mo><msub><mrow><mi>Q</mi></mrow><mrow><mi>n</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> be the number of even permutations of <span><math><mo>[</mo><mi>n</mi><mo>]</mo></math></span> with <em>k</em> descents, odd permutations with <em>k</em> descents, even permutations with <em>k</em> excedances and odd permutations with <em>k</em> excedances, respectively. We show that the four sequences are ultra-synchronised for all <span><math><mi>n</mi><mo>≥</mo><mn>5</mn></math></span>. This proves a strengthening of two conjectures of Dey <span><span>[2]</span></span>.</div></div>\",\"PeriodicalId\":50572,\"journal\":{\"name\":\"Discrete Mathematics\",\"volume\":\"348 8\",\"pages\":\"Article 114521\"},\"PeriodicalIF\":0.7000,\"publicationDate\":\"2025-04-07\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Discrete Mathematics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0012365X25001293\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012365X25001293","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
Synchronicity of descent and excedance enumerators in the alternating subgroup
Generalising the work of Dey [2], we define the notion of ultra-synchronicity of sequences of real numbers. Let be the number of even permutations of with k descents, odd permutations with k descents, even permutations with k excedances and odd permutations with k excedances, respectively. We show that the four sequences are ultra-synchronised for all . This proves a strengthening of two conjectures of Dey [2].
期刊介绍:
Discrete Mathematics provides a common forum for significant research in many areas of discrete mathematics and combinatorics. Among the fields covered by Discrete Mathematics are graph and hypergraph theory, enumeration, coding theory, block designs, the combinatorics of partially ordered sets, extremal set theory, matroid theory, algebraic combinatorics, discrete geometry, matrices, and discrete probability theory.
Items in the journal include research articles (Contributions or Notes, depending on length) and survey/expository articles (Perspectives). Efforts are made to process the submission of Notes (short articles) quickly. The Perspectives section features expository articles accessible to a broad audience that cast new light or present unifying points of view on well-known or insufficiently-known topics.