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Seminar information archive
Seminar information archive ～04/23｜Today's seminar 04/24 | Future seminars 04/25～
thesis presentations
9:15-10:30 Online
Nobuo Iida (Graduate School of Mathematical Sciences University of Tokyo)
A stable homotopy version of monopole contact invariant
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Nobuo Iida (Graduate School of Mathematical Sciences University of Tokyo)
A stable homotopy version of monopole contact invariant
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
11:00-12:15 Online
Jun Okamoto (Graduate School of Mathematical Sciences University of Tokyo)
Convergence of some non-convex energies under various topology
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Jun Okamoto (Graduate School of Mathematical Sciences University of Tokyo)
Convergence of some non-convex energies under various topology
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
11:00-12:15 Online
Yasuhiro Oki (Graduate School of Mathematical Sciences University of Tokyo)
On the connected components of Shimura varieties for CM unitary groups in odd variables
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Yasuhiro Oki (Graduate School of Mathematical Sciences University of Tokyo)
On the connected components of Shimura varieties for CM unitary groups in odd variables
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
13:00-14:15 Online
Tatsuro Kawakami (Graduate School of Mathematical Sciences University of Tokyo)
Studies on the Bogomolov-Sommese vanishing theorem and Du Val del Pezzo surfaces in positive characteristic
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Tatsuro Kawakami (Graduate School of Mathematical Sciences University of Tokyo)
Studies on the Bogomolov-Sommese vanishing theorem and Du Val del Pezzo surfaces in positive characteristic
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
9:15-10:30 Online
Cyuyou Ko (Graduate School of Mathematical Sciences University of Tokyo)
On the Helmholtz decomposition of vector fields with bounded mean oscillation in various domains
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Cyuyou Ko (Graduate School of Mathematical Sciences University of Tokyo)
On the Helmholtz decomposition of vector fields with bounded mean oscillation in various domains
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
11:00-12:15 Online
Masatoshi Goda (Graduate School of Mathematical Sciences University of Tokyo)
Statistical inference for Hawkes processes
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Masatoshi Goda (Graduate School of Mathematical Sciences University of Tokyo)
Statistical inference for Hawkes processes
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
14:45-16:00 Online
Yusuke Sato (Graduate School of Mathematical Sciences University of Tokyo)
Multidimensional continued fractions and Fujiki-Oka resolutions of cyclic quotient singularities
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Yusuke Sato (Graduate School of Mathematical Sciences University of Tokyo)
Multidimensional continued fractions and Fujiki-Oka resolutions of cyclic quotient singularities
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
11:00-12:15 Online
Taketo Sano (Graduate School of Mathematical Sciences University of Tokyo)
On functoriality and spatial refinements of Khovanov homology and its variants
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Taketo Sano (Graduate School of Mathematical Sciences University of Tokyo)
On functoriality and spatial refinements of Khovanov homology and its variants
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
14:45-16:00 Online
Hiroshi Takase (Graduate School of Mathematical Sciences University of Tokyo)
Inverse problems for hyperbolic partial differential equations with time-dependent coefficients
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Hiroshi Takase (Graduate School of Mathematical Sciences University of Tokyo)
Inverse problems for hyperbolic partial differential equations with time-dependent coefficients
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
thesis presentations
14:45-16:00 Online
Mayuko Yamashita (RIMS, Kyoto University)
Differential models for the Anderson dual to bordism theories and invertible QFT’s
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
Mayuko Yamashita (RIMS, Kyoto University)
Differential models for the Anderson dual to bordism theories and invertible QFT’s
[ Reference URL ]
https://forms.gle/bdsntP4pZ4TMaehF9
2022/01/25
Tuesday Seminar on Topology
17:00-18:00 Online
Pre-registration required. See our seminar webpage.
Xiaobing Sheng (The Univesity of Tokyo)
Some obstructions on subgroups of the Brin-Thompson group $2V$ (ENGLISH)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Xiaobing Sheng (The Univesity of Tokyo)
Some obstructions on subgroups of the Brin-Thompson group $2V$ (ENGLISH)
[ Abstract ]
Motivated by Burillo, Cleary and Röver's summary of the obstruction for subgroups of Thompson's group $V$, we investigate the higher dimensional version, the group $2V$ and found out that they have similar obstructions on torsion subgroups and certain Baumslag-Solitar groups.
[ Reference URL ]Motivated by Burillo, Cleary and Röver's summary of the obstruction for subgroups of Thompson's group $V$, we investigate the higher dimensional version, the group $2V$ and found out that they have similar obstructions on torsion subgroups and certain Baumslag-Solitar groups.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2022/01/24
Seminar on Geometric Complex Analysis
10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Junjiro Noguchi (The University of Tokyo)
Analytic Ax-Schanuel Theorem for semi-abelian varieties and Nevanlinna theory (Japanese)
https://u-tokyo-ac-jp.zoom.us/meeting/register/tJ0vcu2rrDIqG9Rv5AT0Mpi37urIkJ1IRldB
Junjiro Noguchi (The University of Tokyo)
Analytic Ax-Schanuel Theorem for semi-abelian varieties and Nevanlinna theory (Japanese)
[ Abstract ]
The present study is motivated by $\textit{Schanuel Conjecture}$, which in particular implies the algebraic independence of $e$ and $\pi$. Our aim is to explore, as a transcendental functional analogue of Schanuel Conjecture, the value distribution theory (Nevanlinna theory) of the entire curve $\widehat{\mathrm{ex}}_A f:=(\exp_Af,f):\mathbf{C} \to A \times \mathrm{Lie}(A)$ associated with an entire curve $f: \mathbf{C} \to \mathrm{Lie}(A)$, where $\exp_A:\mathrm{Lie}(A)\to A$ is an exponential map of a semi-abelian variety $A$.
We firstly give a Nevanlinna theoretic proof to the $\textit{analytic Ax-Schanuel Theorem}$ for semi-abelian varieties, which was proved by J. Ax 1972 in the case of formal power series $\mathbf{C}[[t]]$ (Ax-Schanuel Theorem). We assume some non-degeneracy condition for $f$ such that in the case of $A=(\mathbf{C}^*)^n$ and $\mathrm{Lie}((\mathbf{C}^*)^n)=\mathbf{C}^n$, the elements of the vector-valued function $f(z)-f(0)$ are $\mathbf{Q}$-linearly independent. Then by the method of Nevanlinna theory (the Log Bloch-Ochiai Theorem), we prove that $\mathrm{tr.deg}_\mathbf{C}\, \widehat{\mathrm{ex}}_A f \geq n+ 1.$
Secondly, we prove a $\textit{Second Main Theorem}$ for $\widehat{\mathrm{ex}}_A f$ and an algebraic divisor $D$ on $A \times \mathrm{Lie}(A)$ with compactifications $\bar D \subset \bar A \times \overline{\mathrm{Lie}(A)}$ such that
\[
T_{\widehat{\mathrm{ex}}_Af}(r, L({\bar D})) \leq N_1 (r,
(\widehat{\mathrm{ex}}_A f)^* D)+
\varepsilon T_{\exp_Af}(r)+O(\log r) ~~ ||_\varepsilon.
\]
We will also deal with the intersections of $\widehat{\mathrm{ex}}_Af$ with higher codimensional algebraic cycles of $A \times \mathrm{Lie}(A)$ as well as the case of higher jets.
[ Reference URL ]The present study is motivated by $\textit{Schanuel Conjecture}$, which in particular implies the algebraic independence of $e$ and $\pi$. Our aim is to explore, as a transcendental functional analogue of Schanuel Conjecture, the value distribution theory (Nevanlinna theory) of the entire curve $\widehat{\mathrm{ex}}_A f:=(\exp_Af,f):\mathbf{C} \to A \times \mathrm{Lie}(A)$ associated with an entire curve $f: \mathbf{C} \to \mathrm{Lie}(A)$, where $\exp_A:\mathrm{Lie}(A)\to A$ is an exponential map of a semi-abelian variety $A$.
We firstly give a Nevanlinna theoretic proof to the $\textit{analytic Ax-Schanuel Theorem}$ for semi-abelian varieties, which was proved by J. Ax 1972 in the case of formal power series $\mathbf{C}[[t]]$ (Ax-Schanuel Theorem). We assume some non-degeneracy condition for $f$ such that in the case of $A=(\mathbf{C}^*)^n$ and $\mathrm{Lie}((\mathbf{C}^*)^n)=\mathbf{C}^n$, the elements of the vector-valued function $f(z)-f(0)$ are $\mathbf{Q}$-linearly independent. Then by the method of Nevanlinna theory (the Log Bloch-Ochiai Theorem), we prove that $\mathrm{tr.deg}_\mathbf{C}\, \widehat{\mathrm{ex}}_A f \geq n+ 1.$
Secondly, we prove a $\textit{Second Main Theorem}$ for $\widehat{\mathrm{ex}}_A f$ and an algebraic divisor $D$ on $A \times \mathrm{Lie}(A)$ with compactifications $\bar D \subset \bar A \times \overline{\mathrm{Lie}(A)}$ such that
\[
T_{\widehat{\mathrm{ex}}_Af}(r, L({\bar D})) \leq N_1 (r,
(\widehat{\mathrm{ex}}_A f)^* D)+
\varepsilon T_{\exp_Af}(r)+O(\log r) ~~ ||_\varepsilon.
\]
We will also deal with the intersections of $\widehat{\mathrm{ex}}_Af$ with higher codimensional algebraic cycles of $A \times \mathrm{Lie}(A)$ as well as the case of higher jets.
https://u-tokyo-ac-jp.zoom.us/meeting/register/tJ0vcu2rrDIqG9Rv5AT0Mpi37urIkJ1IRldB
2022/01/21
Colloquium
15:30-16:30 Online
Registration is closed (12:00, January 21).
Yoshiko Ogata (Graduate School of Mathematical Sciences, The University of Tokyo)
Classification of gapped ground state phases in quantum spin systems (JAPANESE)
Registration is closed (12:00, January 21).
Yoshiko Ogata (Graduate School of Mathematical Sciences, The University of Tokyo)
Classification of gapped ground state phases in quantum spin systems (JAPANESE)
Tokyo-Nagoya Algebra Seminar
16:45-18:15 Online
Please see the URL below for details on the online seminar.
Haruhisa Enomoto (Osaka Prefecture University)
Exact-categorical properties of subcategories of abelian categories 2 (Japanese)
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Please see the URL below for details on the online seminar.
Haruhisa Enomoto (Osaka Prefecture University)
Exact-categorical properties of subcategories of abelian categories 2 (Japanese)
[ Abstract ]
Quillen's exact category is a powerful framework for studying extension-closed subcategories of abelian categories, and provides many interesting questions on such subcategories.
In the first talk, I will explain the basics of some properties and invariants of exact categories (e.g. the Jordan-Holder property, simple objects, and Grothendieck monoid).
In the second talk, I will give some results and questions about particular classes of exact categories arising in the representation theory of algebras (e.g. torsion(-free) classes over path algebras and preprojective algebras).
If time permits, I will discuss questions of whether these results can be generalized to extriangulated categories (extension-closed subcategories of triangulated categories).
[ Reference URL ]Quillen's exact category is a powerful framework for studying extension-closed subcategories of abelian categories, and provides many interesting questions on such subcategories.
In the first talk, I will explain the basics of some properties and invariants of exact categories (e.g. the Jordan-Holder property, simple objects, and Grothendieck monoid).
In the second talk, I will give some results and questions about particular classes of exact categories arising in the representation theory of algebras (e.g. torsion(-free) classes over path algebras and preprojective algebras).
If time permits, I will discuss questions of whether these results can be generalized to extriangulated categories (extension-closed subcategories of triangulated categories).
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2022/01/20
Seminar on Probability and Statistics
15:00-16:10 Room # (Graduate School of Math. Sci. Bldg.)
Yoshimasa Uematsu (-)
-
[ Reference URL ]
https://docs.google.com/forms/d/e/1FAIpQLSdH8oP72k7-qsHigZBBZ4F6N-bGIJ6BcOWgKLhted2ohGSBeg/viewform
Yoshimasa Uematsu (-)
-
[ Reference URL ]
https://docs.google.com/forms/d/e/1FAIpQLSdH8oP72k7-qsHigZBBZ4F6N-bGIJ6BcOWgKLhted2ohGSBeg/viewform
2022/01/19
Mathematical Biology Seminar
15:00-16:00 Online
Tsuyoshi Kajiwara (Professor Emeritus, Okayama University)
Destabilization induced by time delay, immunity and absorbing effect
(Japanese)
[ Reference URL ]
オンラインですので，参加希望のかたは稲葉(inaba@ms.u-tokyo.ac.jp)へご連絡ください．
Tsuyoshi Kajiwara (Professor Emeritus, Okayama University)
Destabilization induced by time delay, immunity and absorbing effect
(Japanese)
[ Reference URL ]
オンラインですので，参加希望のかたは稲葉(inaba@ms.u-tokyo.ac.jp)へご連絡ください．
Seminar on Probability and Statistics
14:30-16:00 Room # (Graduate School of Math. Sci. Bldg.)
Martin Hazelton (Otago University)
Dynamic fibre samplers for linear inverse problems
https://docs.google.com/forms/d/e/1FAIpQLSeoXt5v8xdQNFAKTDLoD0lttaHjV17_r7864x11mtxU1EQlhQ/viewform
Martin Hazelton (Otago University)
Dynamic fibre samplers for linear inverse problems
[ Abstract ]
Asia-Pacific Seminar in Probability and Statistics (APSPS)
https://sites.google.com/view/apsps/home
Statistical inverse problems occur when we wish to learn about some random process that is observed only indirectly. Inference in such situations typically involves sampling possible values for the latent variables of interest conditional on the indirect observations. For count data, the latent variables are constrained to lie on a fibre (solution set for the linear system) comprising the integer lattice within a convex polytope.
Sampling the latent counts can be conducted using MCMC methods,through a random walk on this fibre. A major challenge is finding a set of basic moves that ensures connectedness of the walk over the fibre. In principle this can be done by computing a Markov basis of potential moves, but the resulting sampler can be hugely inefficient even when such a basis is computable. In this talk I will describe some current work on developing a dynamic Markov basis that generates moves on the fly. This approach can guarantee irreducibility of the sampler while gaining efficiency by increasing the probability of selecting serviceable sampling directions.
[ Reference URL ]Asia-Pacific Seminar in Probability and Statistics (APSPS)
https://sites.google.com/view/apsps/home
Statistical inverse problems occur when we wish to learn about some random process that is observed only indirectly. Inference in such situations typically involves sampling possible values for the latent variables of interest conditional on the indirect observations. For count data, the latent variables are constrained to lie on a fibre (solution set for the linear system) comprising the integer lattice within a convex polytope.
Sampling the latent counts can be conducted using MCMC methods,through a random walk on this fibre. A major challenge is finding a set of basic moves that ensures connectedness of the walk over the fibre. In principle this can be done by computing a Markov basis of potential moves, but the resulting sampler can be hugely inefficient even when such a basis is computable. In this talk I will describe some current work on developing a dynamic Markov basis that generates moves on the fly. This approach can guarantee irreducibility of the sampler while gaining efficiency by increasing the probability of selecting serviceable sampling directions.
https://docs.google.com/forms/d/e/1FAIpQLSeoXt5v8xdQNFAKTDLoD0lttaHjV17_r7864x11mtxU1EQlhQ/viewform
2022/01/18
Operator Algebra Seminars
16:45-18:15 Online
Miho Mukohara (Univ. Tokyo)
C$^*$-simplicity of relative profinite completions of generalized Baumslag-Solitar groups
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Miho Mukohara (Univ. Tokyo)
C$^*$-simplicity of relative profinite completions of generalized Baumslag-Solitar groups
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tokyo-Nagoya Algebra Seminar
15:00-16:30 Online
Please see the URL below for details on the online seminar.
Haruhisa Enomoto (Osaka Prefecture University)
Exact-categorical properties of subcategories of abelian categories 1 (Japanese)
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Please see the URL below for details on the online seminar.
Haruhisa Enomoto (Osaka Prefecture University)
Exact-categorical properties of subcategories of abelian categories 1 (Japanese)
[ Abstract ]
Quillen's exact category is a powerful framework for studying extension-closed subcategories of abelian categories, and provides many interesting questions on such subcategories.
In the first talk, I will explain the basics of some properties and invariants of exact categories (e.g. the Jordan-Holder property, simple objects, and Grothendieck monoid).
In the second talk, I will give some results and questions about particular classes of exact categories arising in the representation theory of algebras (e.g. torsion(-free) classes over path algebras and preprojective algebras).
If time permits, I will discuss questions of whether these results can be generalized to extriangulated categories (extension-closed subcategories of triangulated categories).
[ Reference URL ]Quillen's exact category is a powerful framework for studying extension-closed subcategories of abelian categories, and provides many interesting questions on such subcategories.
In the first talk, I will explain the basics of some properties and invariants of exact categories (e.g. the Jordan-Holder property, simple objects, and Grothendieck monoid).
In the second talk, I will give some results and questions about particular classes of exact categories arising in the representation theory of algebras (e.g. torsion(-free) classes over path algebras and preprojective algebras).
If time permits, I will discuss questions of whether these results can be generalized to extriangulated categories (extension-closed subcategories of triangulated categories).
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Lie Groups and Representation Theory
17:00-18:00 Room #On line (Graduate School of Math. Sci. Bldg.)
Hideyuki Ishi (Osaka City University)
Strongly visible actions on complex domains (Japanese)
Hideyuki Ishi (Osaka City University)
Strongly visible actions on complex domains (Japanese)
[ Abstract ]
In this century, the Cartan-Hartogs domain and its variations, on which the Bergman kernel function and the Kahler-Einstein metric can be computed explicitly, have been actively studied. Reasoning that strongly visible actions on the domains enable such nice calculations, we introduce a new type of complex domain analogous to the Cartan-Hartogs domain, and present a research plan about harmonic analysis over the domain.
In this century, the Cartan-Hartogs domain and its variations, on which the Bergman kernel function and the Kahler-Einstein metric can be computed explicitly, have been actively studied. Reasoning that strongly visible actions on the domains enable such nice calculations, we introduce a new type of complex domain analogous to the Cartan-Hartogs domain, and present a research plan about harmonic analysis over the domain.
2022/01/13
Information Mathematics Seminar
16:50-18:35 Online
Keita Xagawa (NTT)
Lattice-based cryptography and its applications (Japanese)
https://docs.google.com/forms/d/1WLEbsA2aQTXgdE2ynrumJOG-Z4AVWqcOLC-z42B4nPY
Keita Xagawa (NTT)
Lattice-based cryptography and its applications (Japanese)
[ Abstract ]
Explanation on lattice-based cryptography and its applications
[ Reference URL ]Explanation on lattice-based cryptography and its applications
https://docs.google.com/forms/d/1WLEbsA2aQTXgdE2ynrumJOG-Z4AVWqcOLC-z42B4nPY
2022/01/11
Operator Algebra Seminars
16:45-18:15 Online
Akihiro Miyagawa (Kyoto University)
Rationality for operators in free semicircular elements
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Akihiro Miyagawa (Kyoto University)
Rationality for operators in free semicircular elements
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
17:00-18:00 Online
Joint with Lie Groups and Representation Theory Seminar. See our seminar webpage.
Keiichi Maeta (The Univesity of Tokyo)
On the existence problem of Compact Clifford-Klein forms of indecomposable pseudo-Riemannian symmetric spaces with signature (n,2) (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Joint with Lie Groups and Representation Theory Seminar. See our seminar webpage.
Keiichi Maeta (The Univesity of Tokyo)
On the existence problem of Compact Clifford-Klein forms of indecomposable pseudo-Riemannian symmetric spaces with signature (n,2) (JAPANESE)
[ Abstract ]
For a homogeneous space $G/H$ and its discontinuous group $\Gamma\subset G$, the double coset space $\Gamma\backslash G/H$ is called a Clifford-Klein form of $G/H$. In the study of Clifford-Klein forms, the classification of homogeneous spaces which admit compact Clifford—Klein forms is one of the important open problems, which was introduced by Toshiyuki Kobayashi in 1980s. We consider this problem for indecomposable and reducible pseudo-Riemannian symmetric spaces with signature (n,2). We show the non-existence of compact Clifford-Klein forms for some series of symmetric spaces, and construct new compact Clifford-Klein forms of countably infinite five-dimensional pseudo-Riemannian symmetric spaces with signature (3,2).
[ Reference URL ]For a homogeneous space $G/H$ and its discontinuous group $\Gamma\subset G$, the double coset space $\Gamma\backslash G/H$ is called a Clifford-Klein form of $G/H$. In the study of Clifford-Klein forms, the classification of homogeneous spaces which admit compact Clifford—Klein forms is one of the important open problems, which was introduced by Toshiyuki Kobayashi in 1980s. We consider this problem for indecomposable and reducible pseudo-Riemannian symmetric spaces with signature (n,2). We show the non-existence of compact Clifford-Klein forms for some series of symmetric spaces, and construct new compact Clifford-Klein forms of countably infinite five-dimensional pseudo-Riemannian symmetric spaces with signature (3,2).
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Lie Groups and Representation Theory
17:00-18:00 Room #on line (Graduate School of Math. Sci. Bldg.)
Joint with Tuesday Seminar on Topology.
Keiichi Maeta (The University of Tokyo)
On the existence problem of Compact Clifford-Klein forms of indecomposable pseudo-Riemannian symmetric spaces with signature (n,2) (Japanese)
Joint with Tuesday Seminar on Topology.
Keiichi Maeta (The University of Tokyo)
On the existence problem of Compact Clifford-Klein forms of indecomposable pseudo-Riemannian symmetric spaces with signature (n,2) (Japanese)
[ Abstract ]
For a homogeneous space $G/H$ and its discontinuous group $\Gamma\subset G$, the double coset space $\Gamma\backslash G/H$ is called a Clifford-Klein form of $G/H$. In the study of Clifford-Klein forms, the classification of homogeneous spaces which admit compact Clifford-Klein forms is one of the important open problems, which was introduced by Toshiyuki Kobayashi in 1980s.
We consider this problem for indecomposable and reducible pseudo-Riemannian symmetric spaces with signature (n,2). We show the non-existence of compact Clifford-Klein forms for some series of symmetric spaces, and construct new compact Clifford-Klein forms of countably infinite five-dimensional pseudo-Riemannian symmetric spaces with signature (3,2).
For a homogeneous space $G/H$ and its discontinuous group $\Gamma\subset G$, the double coset space $\Gamma\backslash G/H$ is called a Clifford-Klein form of $G/H$. In the study of Clifford-Klein forms, the classification of homogeneous spaces which admit compact Clifford-Klein forms is one of the important open problems, which was introduced by Toshiyuki Kobayashi in 1980s.
We consider this problem for indecomposable and reducible pseudo-Riemannian symmetric spaces with signature (n,2). We show the non-existence of compact Clifford-Klein forms for some series of symmetric spaces, and construct new compact Clifford-Klein forms of countably infinite five-dimensional pseudo-Riemannian symmetric spaces with signature (3,2).
2022/01/06
Information Mathematics Seminar
16:50-18:35 Online
Hiroshi Fujiwara (BroadBand Tower, Inc.)
Next cyber security strategy of the Japanese Government (Japanese)
https://docs.google.com/forms/d/1I3XD63V937BT_IoqRWBVN67goQAtbkSoIKs-6hfLUAM
Hiroshi Fujiwara (BroadBand Tower, Inc.)
Next cyber security strategy of the Japanese Government (Japanese)
[ Abstract ]
Explanation on next cyber security strategy of the Japanese government
[ Reference URL ]Explanation on next cyber security strategy of the Japanese government
https://docs.google.com/forms/d/1I3XD63V937BT_IoqRWBVN67goQAtbkSoIKs-6hfLUAM
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