{"title":"EDGE WEIGHTING FUNCTIONS ON THE SEMITOTAL DOMINATING SET OF CLAW-FREE GRAPHS","authors":"JIE CHEN, HONGZHANG CHEN, SHOU-JUN XU","doi":"10.1017/s0004972724000017","DOIUrl":"https://doi.org/10.1017/s0004972724000017","url":null,"abstract":"In an isolate-free graph <jats:italic>G</jats:italic>, a subset <jats:italic>S</jats:italic> of vertices is a <jats:italic>semitotal dominating set</jats:italic> of <jats:italic>G</jats:italic> if it is a dominating set of <jats:italic>G</jats:italic> and every vertex in <jats:italic>S</jats:italic> is within distance 2 of another vertex of <jats:italic>S</jats:italic>. The <jats:italic>semitotal domination number</jats:italic> of <jats:italic>G</jats:italic>, denoted by <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000017_inline1.png\" /> <jats:tex-math> $gamma _{t2}(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>, is the minimum cardinality of a semitotal dominating set in <jats:italic>G</jats:italic>. Using edge weighting functions on semitotal dominating sets, we prove that if <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000017_inline2.png\" /> <jats:tex-math> $Gneq N_2$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is a connected claw-free graph of order <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000017_inline3.png\" /> <jats:tex-math> $ngeq 6$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> with minimum degree <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000017_inline4.png\" /> <jats:tex-math> $delta (G)geq 3$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>, then <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000017_inline5.png\" /> <jats:tex-math> $gamma _{t2}(G)leq frac{4}{11}n$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> and this bound is sharp, disproving the conjecture proposed by Zhu <jats:italic>et al.</jats:italic> [‘Semitotal domination in claw-free cubic graphs’, <jats:italic>Graphs Combin.</jats:italic>33(5) (2017), 1119–1130].","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"14 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139767182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ON THE LIMIT SET OF A COMPLEX HYPERBOLIC TRIANGLE GROUP","authors":"MENGQI SHI, JIEYAN WANG","doi":"10.1017/s0004972723001478","DOIUrl":"https://doi.org/10.1017/s0004972723001478","url":null,"abstract":"Let <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001478_inline1.png\" /> <jats:tex-math> $Gamma =langle I_{1}, I_{2}, I_{3}rangle $ </jats:tex-math> </jats:alternatives> </jats:inline-formula> be the complex hyperbolic <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001478_inline2.png\" /> <jats:tex-math> $(4,4,infty )$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> triangle group with <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001478_inline3.png\" /> <jats:tex-math> $I_1I_3I_2I_3$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> being unipotent. We show that the limit set of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001478_inline4.png\" /> <jats:tex-math> $Gamma $ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is connected and the closure of a countable union of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001478_inline5.png\" /> <jats:tex-math> $mathbb {R}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>-circles.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"273 ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139668333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ADOLFO BALLESTER-BOLINCHES, SESUAI Y. MADANHA, TENDAI M. MUDZIIRI SHUMBA, MARÍA C. PEDRAZA-AGUILERA
{"title":"GENERALISED MUTUALLY PERMUTABLE PRODUCTS AND SATURATED FORMATIONS, II","authors":"ADOLFO BALLESTER-BOLINCHES, SESUAI Y. MADANHA, TENDAI M. MUDZIIRI SHUMBA, MARÍA C. PEDRAZA-AGUILERA","doi":"10.1017/s0004972723001430","DOIUrl":"https://doi.org/10.1017/s0004972723001430","url":null,"abstract":"<p>A group <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240129062406367-0762:S0004972723001430:S0004972723001430_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$G=AB$</span></span></img></span></span> is the weakly mutually permutable product of the subgroups <span>A</span> and <span>B</span>, if <span>A</span> permutes with every subgroup of <span>B</span> containing <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240129062406367-0762:S0004972723001430:S0004972723001430_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$A cap B$</span></span></img></span></span> and <span>B</span> permutes with every subgroup of <span>A</span> containing <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240129062406367-0762:S0004972723001430:S0004972723001430_inline3.png\"><span data-mathjax-type=\"texmath\"><span>$A cap B$</span></span></img></span></span>. Weakly mutually permutable products were introduced by the first, second and fourth authors [‘Generalised mutually permutable products and saturated formations’, <span>J. Algebra</span> <span>595</span> (2022), 434–443] who showed that if <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240129062406367-0762:S0004972723001430:S0004972723001430_inline4.png\"><span data-mathjax-type=\"texmath\"><span>$G'$</span></span></img></span></span> is nilpotent, <span>A</span> permutes with every Sylow subgroup of <span>B</span> and <span>B</span> permutes with every Sylow subgroup of <span>A</span>, then <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240129062406367-0762:S0004972723001430:S0004972723001430_inline5.png\"><span data-mathjax-type=\"texmath\"><span>$G^{mathfrak {F}}=A^{mathfrak {F}}B^{mathfrak {F}} $</span></span></img></span></span>, where <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240129062406367-0762:S0004972723001430:S0004972723001430_inline6.png\"><span data-mathjax-type=\"texmath\"><span>$ mathfrak {F} $</span></span></img></span></span> is a saturated formation containing <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240129062406367-0762:S0004972723001430:S0004972723001430_inline7.png\"><span data-mathjax-type=\"texmath\"><span>$ mathfrak {U} $</span></span></img></span></span>, the class of supersoluble groups. In this article we prove results on weakly mutually permutable products concerning <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"6 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139589993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"MULTIPLE SOLUTIONS FOR -LAPLACIAN EQUATIONS WITH NONLINEARITY SUBLINEAR AT ZERO","authors":"SHIBO LIU","doi":"10.1017/s0004972723001405","DOIUrl":"https://doi.org/10.1017/s0004972723001405","url":null,"abstract":"We consider the Dirichlet problem for <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline2.png\" /> <jats:tex-math> $p(x)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>-Laplacian equations of the form <jats:disp-formula> <jats:alternatives> <jats:graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_eqnu1.png\" /> <jats:tex-math> $$ begin{align*} -Delta_{p(x)}u+b(x)vert uvert ^{p(x)-2}u=f(x,u),quad uin W_{0}^{1,p(x)}(Omega). end{align*} $$ </jats:tex-math> </jats:alternatives> </jats:disp-formula> The odd nonlinearity <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline3.png\" /> <jats:tex-math> $f(x,u)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline4.png\" /> <jats:tex-math> $p(x)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>-sublinear at <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline5.png\" /> <jats:tex-math> $u=0$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> but the related limit need not be uniform for <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline6.png\" /> <jats:tex-math> $xin Omega $ </jats:tex-math> </jats:alternatives> </jats:inline-formula>. Except being subcritical, no additional assumption is imposed on <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline7.png\" /> <jats:tex-math> $f(x,u)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> for <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline8.png\" /> <jats:tex-math> $|u|$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> large. By applying Clark’s theorem and a truncation method, we obtain a sequence of solutions with negative energy and approaching the zero function <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001405_inline9.png\" /> <jats:tex-math> $u=0$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"44 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"CONGRUENCES FOR RANKS OF PARTITIONS","authors":"RENRONG MAO","doi":"10.1017/s0004972723001454","DOIUrl":"https://doi.org/10.1017/s0004972723001454","url":null,"abstract":"Ranks of partitions play an important role in the theory of partitions. They provide combinatorial interpretations for Ramanujan’s famous congruences for partition functions. We establish a family of congruences modulo powers of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001454_inline1.png\" /> <jats:tex-math> $5$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> for ranks of partitions.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"71 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"HOMOLOGICAL LINEAR QUOTIENTS AND EDGE IDEALS OF GRAPHS","authors":"NADIA TAGHIPOUR, SHAMILA BAYATI, FARHAD RAHMATI","doi":"10.1017/s0004972723001363","DOIUrl":"https://doi.org/10.1017/s0004972723001363","url":null,"abstract":"It is well known that the edge ideal <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline1.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> of a simple graph <jats:italic>G</jats:italic> has linear quotients if and only if <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline2.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is chordal. We investigate when the property of having linear quotients is inherited by homological shift ideals of an edge ideal. We will see that adding a cluster to the graph <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline3.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> when <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline4.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients results in a graph with the same property. In particular, <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline5.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients when <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline6.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is a block graph. We also show that adding pinnacles to trees preserves the property of having homological linear quotients for the edge ideal of their complements. Furthermore, <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline7.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients for every graph <jats:italic>G</jats:italic> such that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline8.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is a <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline9.png\" /> <jats:tex-math> $lambda $ </jats:tex-math> </jats:alternatives> </jats:inline-formula>-min","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"38 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
MALLORY DOLORFINO, LUKE MARTIN, ZACHARY SLONIM, YUXUAN SUN, YONG YANG
{"title":"ON THE CHARACTERISATION OF ALTERNATING GROUPS BY CODEGREES","authors":"MALLORY DOLORFINO, LUKE MARTIN, ZACHARY SLONIM, YUXUAN SUN, YONG YANG","doi":"10.1017/s0004972723001429","DOIUrl":"https://doi.org/10.1017/s0004972723001429","url":null,"abstract":"Let <jats:italic>G</jats:italic> be a finite group and <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline1.png\" /> <jats:tex-math> $mathrm {Irr}(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> the set of all irreducible complex characters of <jats:italic>G</jats:italic>. Define the codegree of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline2.png\" /> <jats:tex-math> $chi in mathrm {Irr}(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> as <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline3.png\" /> <jats:tex-math> $mathrm {cod}(chi ):={|G:mathrm {ker}(chi ) |}/{chi (1)}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> and let <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline4.png\" /> <jats:tex-math> $mathrm {cod}(G):={mathrm {cod}(chi ) mid chi in mathrm {Irr}(G)}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> be the codegree set of <jats:italic>G</jats:italic>. Let <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline5.png\" /> <jats:tex-math> $mathrm {A}_n$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> be an alternating group of degree <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline6.png\" /> <jats:tex-math> $n ge 5$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>. We show that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline7.png\" /> <jats:tex-math> $mathrm {A}_n$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is determined up to isomorphism by <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001429_inline8.png\" /> <jats:tex-math> $operatorname {cod}(mathrm {A}_n)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"31 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"COMPLETE EMBEDDINGS OF GROUPS","authors":"MARTIN R. BRIDSON, HAMISH SHORT","doi":"10.1017/s0004972723001442","DOIUrl":"https://doi.org/10.1017/s0004972723001442","url":null,"abstract":"Every countable group <jats:italic>G</jats:italic> can be embedded in a finitely generated group <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001442_inline1.png\" /> <jats:tex-math> $G^*$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> that is hopfian and <jats:italic>complete</jats:italic>, that is, <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001442_inline2.png\" /> <jats:tex-math> $G^*$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has trivial centre and every epimorphism <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001442_inline3.png\" /> <jats:tex-math> $G^*to G^*$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is an inner automorphism. Every finite subgroup of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001442_inline4.png\" /> <jats:tex-math> $G^*$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is conjugate to a finite subgroup of <jats:italic>G</jats:italic>. If <jats:italic>G</jats:italic> has a finite presentation (respectively, a finite classifying space), then so does <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001442_inline5.png\" /> <jats:tex-math> $G^*$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>. Our construction of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001442_inline6.png\" /> <jats:tex-math> $G^*$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> relies on the existence of closed hyperbolic 3-manifolds that are asymmetric and non-Haken.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"396 2 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"SOLVABLE GROUPS WHOSE NONNORMAL SUBGROUPS HAVE FEW ORDERS","authors":"LIJUAN HE, HENG LV, GUIYUN CHEN","doi":"10.1017/s0004972723001168","DOIUrl":"https://doi.org/10.1017/s0004972723001168","url":null,"abstract":"Suppose that <jats:italic>G</jats:italic> is a finite solvable group. Let <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001168_inline1.png\" /> <jats:tex-math> $t=n_c(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> denote the number of orders of nonnormal subgroups of <jats:italic>G</jats:italic>. We bound the derived length <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001168_inline2.png\" /> <jats:tex-math> $dl(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> in terms of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001168_inline3.png\" /> <jats:tex-math> $n_c(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>. If <jats:italic>G</jats:italic> is a finite <jats:italic>p</jats:italic>-group, we show that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001168_inline4.png\" /> <jats:tex-math> $|G'|leq p^{2t+1}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> and <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001168_inline5.png\" /> <jats:tex-math> $dl(G)leq lceil log _2(2t+3)rceil $ </jats:tex-math> </jats:alternatives> </jats:inline-formula>. If <jats:italic>G</jats:italic> is a finite solvable nonnilpotent group, we prove that the sum of the powers of the prime divisors of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001168_inline6.png\" /> <jats:tex-math> $|G'|$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is less than <jats:italic>t</jats:italic> and that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001168_inline7.png\" /> <jats:tex-math> $dl(G)leq lfloor 2(t+1)/3rfloor +1$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"109 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139052909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"DIVISIBILITY OF SUMS OF PARTITION NUMBERS BY MULTIPLES OF 2 AND 3","authors":"Nayandeep Deka Baruah","doi":"10.1017/s0004972723001351","DOIUrl":"https://doi.org/10.1017/s0004972723001351","url":null,"abstract":"\u0000\t <jats:p>We show that certain sums of partition numbers are divisible by multiples of 2 and 3. For example, if <jats:inline-formula>\u0000\t <jats:alternatives>\u0000\t\t<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001351_inline1.png\" />\u0000\t\t<jats:tex-math>\u0000$p(n)$\u0000</jats:tex-math>\u0000\t </jats:alternatives>\u0000\t </jats:inline-formula> denotes the number of unrestricted partitions of a positive integer <jats:italic>n</jats:italic> (and <jats:inline-formula>\u0000\t <jats:alternatives>\u0000\t\t<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001351_inline2.png\" />\u0000\t\t<jats:tex-math>\u0000$p(0)=1$\u0000</jats:tex-math>\u0000\t </jats:alternatives>\u0000\t </jats:inline-formula>, <jats:inline-formula>\u0000\t <jats:alternatives>\u0000\t\t<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001351_inline3.png\" />\u0000\t\t<jats:tex-math>\u0000$p(n)=0$\u0000</jats:tex-math>\u0000\t </jats:alternatives>\u0000\t </jats:inline-formula> for <jats:inline-formula>\u0000\t <jats:alternatives>\u0000\t\t<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001351_inline4.png\" />\u0000\t\t<jats:tex-math>\u0000$n<0$\u0000</jats:tex-math>\u0000\t </jats:alternatives>\u0000\t </jats:inline-formula>), then for all nonnegative integers <jats:italic>m</jats:italic>, <jats:disp-formula>\u0000\t <jats:alternatives>\u0000\t\t<jats:graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001351_eqnu1.png\" />\u0000\t\t<jats:tex-math>\u0000$$ begin{align*}sum_{k=0}^infty p(24m+23-omega(-2k))+sum_{k=1}^infty p(24m+23-omega(2k))equiv 0~ (text{mod}~144),end{align*} $$\u0000</jats:tex-math>\u0000\t </jats:alternatives>\u0000\t </jats:disp-formula></jats:p>\u0000\t <jats:p>where <jats:inline-formula>\u0000\t <jats:alternatives>\u0000\t\t<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001351_inline5.png\" />\u0000\t\t<jats:tex-math>\u0000$omega (k)=k(3k+1)/2$\u0000</jats:tex-math>\u0000\t </jats:alternatives>\u0000\t </jats:inline-formula>.</jats:p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"3 9","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138945112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}