{"title":"Compact Hyperbolic Coxeter Five-Dimensional Polytopes with Nine Facets","authors":"Jiming Ma, Fangting Zheng","doi":"10.1007/s00031-023-09830-3","DOIUrl":"https://doi.org/10.1007/s00031-023-09830-3","url":null,"abstract":"<p>In this paper, we obtain a complete classification of compact hyperbolic Coxeter five-dimensional polytopes with nine facets.</p>","PeriodicalId":49423,"journal":{"name":"Transformation Groups","volume":"18 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138567876","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}
{"title":"The Limit Set for Representations of Discrete Subgroups of $$text {PU}(1,n)$$ by the Plücker Embedding","authors":"Haremy Zuñiga","doi":"10.1007/s00031-023-09829-w","DOIUrl":"https://doi.org/10.1007/s00031-023-09829-w","url":null,"abstract":"<p>Let <span>(Gamma )</span> be a discrete subgroup of <span>(text {PU}(1,n))</span>. In this work, we look at the induced action of <span>(Gamma )</span> on the projective space <span>(mathbb {P}(wedge ^{k+1}mathbb {C}^{n+1}))</span> by the Plücker embedding, where <span>(wedge ^{k+1})</span> denotes the exterior power. We define a limit set for this action called the <i>k</i>-Chen-Greenberg limit set, which extends the classical definition of the Chen-Greenberg limit set <span>(L(Gamma ))</span>, and we show several of its properties. We prove that its Kulkarni limit set is the union taken over all <span>(pin L(Gamma ))</span> of the projective subspace generated by all <i>k</i>-planes that contain <i>p</i> or are contained in <span>(p^{perp })</span> via the Plücker embedding. We also prove a duality between both limit sets.</p>","PeriodicalId":49423,"journal":{"name":"Transformation Groups","volume":"33 2","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138508437","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}
{"title":"Which Schubert Varieties are Hessenberg Varieties?","authors":"Laura Escobar, Martha Precup, John Shareshian","doi":"10.1007/s00031-023-09825-0","DOIUrl":"https://doi.org/10.1007/s00031-023-09825-0","url":null,"abstract":"<p>After proving that every Schubert variety in the full flag variety of a complex reductive group <i>G</i> is a general Hessenberg variety, we show that not all such Schubert varieties are adjoint Hessenberg varieties. In fact, in types A and C, we provide pattern avoidance criteria implying that the proportion of Schubert varieties that are adjoint Hessenberg varieties approaches zero as the rank of <i>G</i> increases. We show also that in type A, some Schubert varieties are not isomorphic to any adjoint Hessenberg variety.</p>","PeriodicalId":49423,"journal":{"name":"Transformation Groups","volume":"61 2","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138508439","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}
{"title":"On the Invariant and Anti-Invariant Cohomologies of Hypercomplex Manifolds","authors":"Mehdi Lejmi, Nicoletta Tardini","doi":"10.1007/s00031-023-09828-x","DOIUrl":"https://doi.org/10.1007/s00031-023-09828-x","url":null,"abstract":"<p>A hypercomplex structure (<i>I</i>, <i>J</i>, <i>K</i>) on a manifold <i>M</i> is said to be <span>(C^infty )</span>-pure-and-full if the Dolbeault cohomology <span>(H^{2,0}_{partial }(M,I))</span> is the direct sum of two natural subgroups called the <span>(overline{J})</span>-invariant and the <span>(overline{J})</span>-anti-invariant subgroups. We prove that a compact hypercomplex manifold that satisfies the quaternionic version of the <span>(dd^c)</span>-Lemma is <span>(C^infty )</span>-pure-and-full. Moreover, we study the dimensions of the <span>(overline{J})</span>-invariant and the <span>(overline{J})</span>-anti-invariant subgroups, together with their analogue in the Bott-Chern cohomology. For instance, in real dimension 8, we characterize the existence of hyperkähler with torsion metrics in terms of the dimension of the <span>(overline{J})</span>-invariant subgroup. We also study the existence of special hypercomplex structures on almost abelian solvmanifolds.</p>","PeriodicalId":49423,"journal":{"name":"Transformation Groups","volume":"62 3","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138508438","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}
{"title":"ON THE BRUHAT $$ mathcal{G} $$-ORDER BETWEEN LOCAL SYSTEMS ON THE B-ORBITS IN A HERMITIAN SYMMETRIC VARIETY","authors":"Michele Carmassi","doi":"10.1007/s00031-023-09824-1","DOIUrl":"https://doi.org/10.1007/s00031-023-09824-1","url":null,"abstract":"","PeriodicalId":49423,"journal":{"name":"Transformation Groups","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135959830","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}
Daniele Angella, Simone Calamai, Francesco Pediconi, Cristiano Spotti
{"title":"A Moment Map for Twisted-Hamiltonian Vector Fields on Locally Conformally Kähler Manifolds","authors":"Daniele Angella, Simone Calamai, Francesco Pediconi, Cristiano Spotti","doi":"10.1007/s00031-023-09815-2","DOIUrl":"https://doi.org/10.1007/s00031-023-09815-2","url":null,"abstract":"Abstract We extend the classical Donaldson-Fujiki interpretation of the scalar curvature as moment map in Kähler geometry to the wider framework of locally conformally Kähler geometry.","PeriodicalId":49423,"journal":{"name":"Transformation Groups","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136263206","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}
{"title":"Compactifications of Moduli of G-Bundles and Conformal Blocks","authors":"Avery Wilson","doi":"10.1007/s00031-023-09820-5","DOIUrl":"https://doi.org/10.1007/s00031-023-09820-5","url":null,"abstract":"","PeriodicalId":49423,"journal":{"name":"Transformation Groups","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136108416","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}