{"title":"Bergman Operators on Clifford Monogenic Bergman Spaces","authors":"Karen Avetisyan, Klaus Gürlebeck","doi":"10.1007/s00006-025-01401-x","DOIUrl":"10.1007/s00006-025-01401-x","url":null,"abstract":"<div><p>Weighted Bergman projection operators on the Clifford monogenic Bergman spaces over the real ball of <span>({mathbb R}^n)</span> have been already studied in a paper of Ren and Malonek. We extend and generalize their results by considering more general Bergman nonprojection operators and stating a necessary and sufficient condition for them to be bounded on weighted Lebesgue spaces. Sharp estimates for the weighted monogenic Bergman kernel are also given.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 4","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145166786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"E(n)-coactions on Semisimple Clifford Algebras","authors":"Fabio Renda","doi":"10.1007/s00006-025-01399-2","DOIUrl":"10.1007/s00006-025-01399-2","url":null,"abstract":"<div><p>Let <i>E</i>(<i>n</i>) be the <span>(2^{n+1})</span>-dimensional Hopf algebra generated by anti-commuting elements <span>(g,x_1, ldots , x_n)</span>, with <i>g</i> grouplike, each <span>(x_i)</span> skew-primitive, and <span>(g^2=1)</span>, <span>(x_i^2=0)</span>. In this article we prove that <i>E</i>(<i>n</i>)-coactions over a finite-dimensional algebra <i>A</i> are classified by tuples <span>((varphi , d_1, ldots , d_n))</span> consisting of an involution <span>(varphi )</span> and a family <span>((d_i)_{i=1,ldots ,n})</span> of <span>(varphi )</span>-derivations satisfying appropriate conditions. Tuples of maps can be replaced by tuples of suitable elements <span>((c, u_1, ldots , u_n))</span>, whenever <i>A</i> is a semisimple Clifford algebra.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 4","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145164278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Fast Structure-Preserving Method for Dual Quaternion Singular Value Decomposition","authors":"Wenxv Ding, Ying Li, Musheng Wei","doi":"10.1007/s00006-025-01397-4","DOIUrl":"10.1007/s00006-025-01397-4","url":null,"abstract":"<div><p>In this paper, we establish a novel dual matrix representation for dual quaternion matrices, which forms the foundation for a fast and innovative dual structure-preserving algorithm for dual quaternion singular value decomposition (DQSVD). By leveraging the dual quaternion Householder transformation and exploiting the existing properties of dual quaternions, we design a structure-preserving algorithm. This algorithm has a remarkable advantage in that it can convert quaternion operations in the process of bidiagonalizing the dual quaternion matrix into a dual matrix during DQSVD into real operations. As a result, computational efficiency is significantly enhanced. To verify the effectiveness of our proposed algorithm, we present a series of numerical examples. In these examples, we construct the dual complex matrix representation of color images and apply the concept of the structure-preserving algorithm to the dual complex singular value decomposition (DCSVD). This has been successfully employed in the watermark design of color images.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Boundedness of Multiparameter Forelli–Rudin Type Operators on Product (L^p) Spaces over Tubular Domains","authors":"Lvchang Li, Yuheng Liang, Haichou Li","doi":"10.1007/s00006-025-01395-6","DOIUrl":"10.1007/s00006-025-01395-6","url":null,"abstract":"<div><p>In this paper, we introduce and study two classes of multiparameter Forelli–Rudin type operators from <span>(L^{vec {p}}left( {mathcal {D}}right) )</span> to <span>(L^{vec {q}}left( {mathcal {D}}right) )</span>, especially on their boundedness, where <span>(L^{vec {p}}left( {mathcal {D}}right) )</span> and <span>(L^{vec {q}}left( {mathcal {D}}right) )</span> are both weighted Lebesgue spaces over the Cartesian product of two tubular domains <span>(T_B)</span>, with mixed-norm and appropriate weights. We completely characterize the boundedness of these two operators when <span>(1le vec {p}le vec {q}<infty )</span>. Moreover, we provide the necessary and sufficient condition of the case that <span>(vec {q}=(infty ,infty ))</span>. As an application, we obtain the boundedness of three common classes of integral operators, including the weighted multiparameter Bergman-type projection and the weighted multiparameter Berezin-type transform.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Scaled-Hyperbolic Clifford Algebras","authors":"Ilwoo Cho","doi":"10.1007/s00006-025-01393-8","DOIUrl":"10.1007/s00006-025-01393-8","url":null,"abstract":"<div><p>In this paper, starting from recently known scaled hypercomplexes <span>({mathbb {H}}_{t})</span>, we define scaled hyperbolics <span>({mathbb {D}}_{t})</span> for scales <span>(tin {mathbb {R}})</span>. In particular, the <span>(left( -1right) )</span>-scaled hyperbolics <span>({mathbb {D}}_{-1})</span> is isomorphic to the complex field <span>({mathbb {C}})</span>, the 0-scaled hyperbolics <span>({mathbb {D}}_{0})</span> is isomorphic to the dual numbers <span>({textbf{D}})</span>, and the 1-scaled hyperbolics <span>({mathbb {D}}_{1})</span> is isomorphic to the classical hyperbolic numbers <span>({mathcal {D}})</span>. For any fixed <span>(tin {mathbb {R}})</span>, initiated from the <i>t</i>-scaled hyperbolics <span>({mathbb {D}}_{t})</span>, we construct the <i>t</i>-scaled-hyperbolic Clifford algebra <span>({mathscr {C}}_{t}=underrightarrow{textrm{lim}}{mathscr {C}}_{t,n})</span>, where <span>({mathscr {C}}_{t,n})</span> are the <i>n</i>-th <i>t</i>-scaled-hyperbolic Clifford algebras for all <span>(nin {mathbb {N}}cup left{ 0right} )</span>, with <span>({mathscr {C}}_{t,0}={mathbb {R}})</span> and <span>({mathscr {C}}_{t,1}={mathbb {D}}_{t})</span>, just like the classical Clifford algebra <span>({mathscr {C}}={mathscr {C}}_{-1})</span>. To analyze this <span>({mathbb {R}})</span>-algebra <span>({mathscr {C}}_{t})</span>, we establish an operator algebra <span>({mathscr {M}}_{t})</span> (over <span>({mathbb {C}})</span>, as usual), containing <span>({mathscr {C}}_{t})</span>, and then construct a free-probabilistic structure <span>(left( {mathscr {M}}_{t},tau _{t}right) )</span>. From the operator theory, operator algebra and free probability on <span>({mathscr {M}}_{t})</span>, we apply these analysis for studying <span>({mathscr {C}}_{t}.)</span></p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Exploiting Degeneracy in Projective Geometric Algebra","authors":"John Bamberg, Jeff Saunders","doi":"10.1007/s00006-025-01392-9","DOIUrl":"10.1007/s00006-025-01392-9","url":null,"abstract":"<div><p>The last two decades, since the seminal work of Selig [18], has seen projective geometric algebra (PGA) gain popularity as a modern coordinate-free framework for doing classical Euclidean geometry and other Cayley-Klein geometries. This framework is based upon a degenerate Clifford algebra, and it is the purpose of this paper to delve deeper into its internal algebraic structure and extract meaningful information for the purposes of PGA. This includes exploiting the split extension structure to realise the natural decomposition of elements of this Clifford algebra into Euclidean and ideal parts. This leads to a beautiful demonstration of how Playfair’s axiom for affine geometry arises from the ambient degenerate quadratic space. The highlighted split extension property of the Clifford algebra also corresponds to a splitting of the group of units and the Lie algebra of bivectors. Central to these results is that the degenerate Clifford algebra <span>({{,textrm{Cl},}}(V))</span> is isomorphic to the twisted trivial extension <span>({{,textrm{Cl},}}(V/mathbb {F}{e_{0}})ltimes _alpha {{,textrm{Cl},}}(V/mathbb {F}{e_{0}}))</span>, where <span>({e_{0}})</span> is a degenerate vector and <span>(alpha )</span> is the grade-involution.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00006-025-01392-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Probabilities with Values in Scaled Hyperbolic Numbers","authors":"Daniel Alpay, Ilwoo Cho","doi":"10.1007/s00006-025-01394-7","DOIUrl":"10.1007/s00006-025-01394-7","url":null,"abstract":"<div><p>In this paper, we introduce a notion of a probabilistic measure which takes values in <i>t</i>-scaled hyperbolic numbers for <span>(tin mathbb {R})</span>, with a system of axioms generalizing directly Kolmogorov’s axioms. i.e., we establish a suitable measure theory in the set <span>(mathbb {D}_{t})</span> of all <i>t</i>-scaled hyperbolic numbers for arbitrarily fixed <span>(tin mathbb {R})</span>.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00006-025-01394-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145143420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Symmetry of Hilbert Transformation in (mathbb {R}^3)","authors":"Pei Dang, Hua Liu, Tao Qian","doi":"10.1007/s00006-025-01387-6","DOIUrl":"10.1007/s00006-025-01387-6","url":null,"abstract":"<div><p>In this paper we study symmetry properties of the Hilbert transformation of the three real variables in the quaternion setting. In order to describe the symmetry properties we introduce the group <span>(rtextrm{Spin}(3)+mathbb {R}^3)</span> which is essentially an extension of the ax+b group. The study concludes that the Hilbert transformation has certain characteristic symmetry properties in terms of <span>(rtextrm{Spin}(3)+mathbb {R}^3.)</span> We first obtain the spinor representation of the group induced by one of <span>(textrm{Spin}(2))</span> in <span>(mathbb {H})</span>. Then we decompose the natural representation of <span>(rtextrm{Spin}(3)+mathbb {R}^3)</span> into the direct sum of some two irreducible spinor representations, by which we characterize the Hilbert transformation in <span>(mathbb {R}^3)</span>. Precisely, we show that a nontrivial operator is essentially the Hilbert transformation if and only if it is invariant under the action of the <span>(rtextrm{Spin}(3)+mathbb {R}^3)</span> group.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"GAGPT and Its Application to the Interactive Learning of Geometric Algebra","authors":"Jian Wang, Pei Du, Zhuo Zhao, Wen Luo, Zhaoyuan Yu, Linwang Yuan","doi":"10.1007/s00006-025-01385-8","DOIUrl":"10.1007/s00006-025-01385-8","url":null,"abstract":"<div><p>To address the challenges of high specialization and fragmented learning resources in Geometric Algebra (GA), this paper introduces a multi-task Geometric Algebraic Large Language Model (GAGPT), which is built upon a GA vector base, a GA knowledge graph, and a GA multi-tasking agent. Additionally, to facilitate interactive GA teaching, the paper proposes the development of two specialized agents: a GA knowledge Q&A agent and a GA interactive exercises agent. The GAGPT is equipped with comprehensive GA contextual background information by constructing a GA vector base from an extensively curated GA corpus. A GA Knowledge Graph is developed from the selected corpus to provide the model with the necessary GA rules. In the GA knowledge Q&A experiment, the accuracy of both formula-based and concept-based quizzes was improved by 46% and 42%, respectively, when compared to GPT-4o. Moreover, in the experiment involving the gradual generation of GA exercises, GAGPT demonstrated superior performance, while GPT-4o, despite utilizing the appropriate GA calculation formulas, made computational errors that led to incorrect results.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Generalized Degenerate Clifford and Lipschitz Groups in Geometric Algebras","authors":"Ekaterina Filimoshina, Dmitry Shirokov","doi":"10.1007/s00006-025-01390-x","DOIUrl":"10.1007/s00006-025-01390-x","url":null,"abstract":"<div><p>This paper introduces and studies generalized degenerate Clifford and Lipschitz groups in geometric (Clifford) algebras. These Lie groups preserve the direct sums of the subspaces determined by the grade involution and reversion under the adjoint and twisted adjoint representations in degenerate geometric algebras. We prove that the generalized degenerate Clifford and Lipschitz groups can be defined using centralizers and twisted centralizers of fixed grades subspaces and the norm functions that are widely used in the theory of spin groups. We study the relations between these groups and consider them in the particular cases of plane-based geometric algebras and Grassmann algebras. The corresponding Lie algebras are studied. The presented groups are interesting for the study of generalized degenerate spin groups and applications in computer science, physics, and engineering.</p></div>","PeriodicalId":7330,"journal":{"name":"Advances in Applied Clifford Algebras","volume":"35 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}