{"title":"A geometric model of linear fractional transformations","authors":"S. Matsievsky","doi":"10.5922/0321-4796-2022-53-8","DOIUrl":"https://doi.org/10.5922/0321-4796-2022-53-8","url":null,"abstract":"A model of linear fractional transformations of the complex plane in the form of points of the complex three-dimensional projective space without a linear “forbidden” quadric is presented. A model of real linear fractional transformations of the complex plane in the form of points of the real three-dimensional projective space without a linear “forbidden” quadric is presented. A geometric separation of points corresponding to parabolic, hyperbolic and elliptic real linear fractional transformations by a “parabolic” cone touching the forbidden quadric is found. Some properties of model points corresponding to real linear fractional transformations are found. Some properties of model points corresponding to fundamental groups transformations of biconnected domains of the complex plane are found.","PeriodicalId":114406,"journal":{"name":"Differential Geometry of Manifolds of Figures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132880476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On quasi-Sasakian structure on a totally umbilical hypersurface of a six-dimensional Hermitian planar submanifold of Cayley algebra","authors":"G. Banaru","doi":"10.5922/0321-4796-2022-53-1","DOIUrl":"https://doi.org/10.5922/0321-4796-2022-53-1","url":null,"abstract":"Six-dimensional planar submanifolds of Cayley algebra equipped with almost Hermitian structures induced by Brown — Gray three-fold vector cross products in are considered. We select the case when the almost Hermitian structures on such six-dimensional planar submanifolds of Cayley algebra are Hermitian, i. e. these structures are integrable. We study almost contact metric structures on totally umbilical hypersurfaces in such six-dimensional Hermitian planar submanifolds of the octave algebra. We prove that if these almost contact metric structures on a totally umbilical hypersurface of a six-dimensional Hermitian planar submanifold of Cayley algebra are quasi-Sasakian, then they are Sasakian.","PeriodicalId":114406,"journal":{"name":"Differential Geometry of Manifolds of Figures","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116459908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Affine transformations of the tangent bundle with a complete lift connection over a manifold with a linear connection of special type","authors":"A. Y. Sultanov, G. A. Sultanova, N.V. Sadovnikov","doi":"10.5922/0321-4796-2021-52-13","DOIUrl":"https://doi.org/10.5922/0321-4796-2021-52-13","url":null,"abstract":"The theory of tangent bundles over a differentiable manifold M belongs to the geometry and topology of manifolds and is an intensively developing area of the theory of fiber spaces. The foundations of the theory of fibered spaces were laid in the works of S. Eresman, A. Weil, A. Morimoto, S. Sasaki, K. Yano, S. Ishihara. Among Russian scientists, tangent bundles were investigated by A. P. Shirokov, V. V. Vishnevsky, V. V. Shurygin, B. N. Shapukov and their students.\u0000\u0000In the study of automorphisms of generalized spaces, the question of infinitesimal transformations of connections in these spaces is of great importance. K. Yano, G. Vrancianu, P. A. Shirokov, I. P. Egorov, A. Z. Petrov, A. V. Aminova and others have studied movements in different spaces. The works of K. Sato and S. Tanno are devoted to the motions and automorphisms of tangent bundles. Infinitesimal affine collineations in tangent bundles with a synectic connection were considered by H. Shadyev.\u0000\u0000At present, the question of the motions of fibered spaces is considered in the works of A. Ya. Sultanov, in which infinitesimal transformations of a bundle of linear frames with a complete lift connection, the Lie algebra of holomorphic affine vector fields in arbitrary Weyl bundles are investigated. In this paper we obtain exact upper bounds for the dimensions of Lie algebras of infinitesimal affine transformations in tangent bundles with a synectic connection A. P. Shyrokov.","PeriodicalId":114406,"journal":{"name":"Differential Geometry of Manifolds of Figures","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124288163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Invariance of some classes of almost Hermitian structures concerning to the one-parameter group of diffeomorphisms generated by the Lie vector field","authors":"S. V. Khokhlov, L. Ignatochkina","doi":"10.5922/0321-4796-2022-53-12","DOIUrl":"https://doi.org/10.5922/0321-4796-2022-53-12","url":null,"abstract":"Finding the conditions for the invariance of geometric objects under the action of transformation groups is one of the main objects of geometric research. Almost Hermitian structures and structures of the Gray — Hervella classification on smooth manifolds are considered in this paper. All arguments are given using invariant Koszul’s calculus. Conditions for the invariance of the Kähler form in type structures are investigated and it is shown that the Kähler form is covariantly constant with respect to the Lie vector field. Conditions for the invariance of the Riemannian metric under the action of a one-parameter group of diffeomorphisms generated by a Lie vector field are studied. A criterion for the invariance of an almost complex structure with respect to the local group of diffeomorphisms generated by the Lie vector field in the class W4 is proved. Conditions for the invariance of an operator of an almost complex structure, a tensor of a Riemannian metric, are proved. It is established that the invariance of the Riemannian structure g implies the invariance of the operator of an almost complex structure for some class of manifolds according to the Gray — Hervella classification, and conditions for the covariant constancy of the Lie form in certain classes of manifolds of dimensions above four were obtained. It is proved that the Lie form is covariantly constant in some classes of the type of dimensions above four.","PeriodicalId":114406,"journal":{"name":"Differential Geometry of Manifolds of Figures","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128028219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On some characteristics of subset of prime numbers","authors":"V. Malakhovsky","doi":"10.5922/0321-4796-2019-50-12","DOIUrl":"https://doi.org/10.5922/0321-4796-2019-50-12","url":null,"abstract":"The set of prime numbers p ≥ 5 is divided into two nonoverlapping subset P1 = {6k1 1}, P2 = {6k2 + 1}, where ki ⋲ A (i = 1,2). Subsets A1, A2 of natural numbers is defined by differences Ai = NBi, where B1, B2 are subset {j1}, {j2} defining subsets {6j1 – 1}, {6j2 + 1} of odd composite numbers. In [1] is proved two theorems permitting easily find by means of arithmetic progression subset Bi for ji a ⋲ N. The tables of numbers ki for a = 500 are defined and some characteristic of subsets P1, P2 are given.","PeriodicalId":114406,"journal":{"name":"Differential Geometry of Manifolds of Figures","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114342937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The founder of of the Kaliningrad Scientific Geometrical School Vladislav Stepanovich Malakhovsky","authors":"M. Kretov, T. Funtikova, Y. Shevchenko","doi":"10.5922/0321-4796-2019-50-1","DOIUrl":"https://doi.org/10.5922/0321-4796-2019-50-1","url":null,"abstract":"A brief biography of the corresponding member of the Russian Academy of Natural Sciences, Honored Scientist of the Russian Federation, Honorary Doctor of Science of the Baltic Federal University named after I. Kant, Professor and Consultant of the Institute of Physical and Mathematical Sciences and IT of the Immanuil Kant Baltic Federal University. The scientific and pedagogical work of a scientist for 65 years is analyzed. Shows the active life position of the hero of the day while studying at school, at Tomsk University and also while working at the Tomsk and Immanuil Kant Baltic Federal University to the present. References to some articles are given in which Vladislav Stepanovich’s activities are described in more detail in all areas up to previous anniversaries. The abstract of publications on number theory published by the hero of the last five years is given, in which for the first time some interesting patterns are established in special subsets of prime numbers.","PeriodicalId":114406,"journal":{"name":"Differential Geometry of Manifolds of Figures","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114437236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}