{"title":"Linear independence of coherent systems associated to discrete subgroups","authors":"Ulrik Enstad, Jordy Timo van Velthoven","doi":"10.1112/blms.13226","DOIUrl":"https://doi.org/10.1112/blms.13226","url":null,"abstract":"<p>This note considers the finite linear independence of coherent systems associated to discrete subgroups. We show by simple arguments that such coherent systems of amenable groups are linearly independent whenever the associated twisted group ring does not contain any nontrivial zero divisors. We verify the latter for discrete subgroups in nilpotent Lie groups. For the particular case of time-frequency translates of Euclidean space, our approach provides a simple and self-contained proof of the Heil–Ramanathan–Topiwala conjecture for subsets of arbitrary discrete subgroups.</p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"57 2","pages":"315-329"},"PeriodicalIF":0.8,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/blms.13226","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A finiteness theorem for universal \u0000 \u0000 m\u0000 $m$\u0000 -gonal forms","authors":"Byeong Moon Kim, Dayoon Park","doi":"10.1112/blms.13217","DOIUrl":"https://doi.org/10.1112/blms.13217","url":null,"abstract":"<p>In this paper, we study the universal <span></span><math>\u0000 <semantics>\u0000 <mi>m</mi>\u0000 <annotation>$m$</annotation>\u0000 </semantics></math>-gonal forms. More precisely, we study the growth of the size of the finite set <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>{</mo>\u0000 <mn>1</mn>\u0000 <mo>,</mo>\u0000 <mn>2</mn>\u0000 <mo>,</mo>\u0000 <mtext>…</mtext>\u0000 <mo>,</mo>\u0000 <msub>\u0000 <mi>γ</mi>\u0000 <mi>m</mi>\u0000 </msub>\u0000 <mo>}</mo>\u0000 </mrow>\u0000 <annotation>$lbrace 1,2,ldots, gamma _mrbrace$</annotation>\u0000 </semantics></math> (<span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>γ</mi>\u0000 <mi>m</mi>\u0000 </msub>\u0000 <annotation>$gamma _m$</annotation>\u0000 </semantics></math> asymptotically increases as <span></span><math>\u0000 <semantics>\u0000 <mi>m</mi>\u0000 <annotation>$m$</annotation>\u0000 </semantics></math> increases) which characterize the universality of <span></span><math>\u0000 <semantics>\u0000 <mi>m</mi>\u0000 <annotation>$m$</annotation>\u0000 </semantics></math>-gonal forms.</p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"57 2","pages":"625-637"},"PeriodicalIF":0.8,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/blms.13217","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}