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Seminar information archive
Seminar information archive ～07/02｜Today's seminar 07/03 | Future seminars 07/04～
2025/07/02
Number Theory Seminar
17:00-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)
Amoru Fujii (University of Tokyo)
Parametrization of supercuspidal representations of depth-zero for some simple adjoint groups (日本語)
Amoru Fujii (University of Tokyo)
Parametrization of supercuspidal representations of depth-zero for some simple adjoint groups (日本語)
[ Abstract ]
We construct a surjective map from the set of conjugacy classes of depth-zero enhanced L-parameters to that of isomorphism classes of depth-zero supercuspidal representations for simple adjoint groups, and check the bijectivity in various cases. We also prove that the Hiraga--Ichino--Ikeda conjecture on the formal degree of essentially square-integrable representations holds for this parametrization if it is bijective.
We construct a surjective map from the set of conjugacy classes of depth-zero enhanced L-parameters to that of isomorphism classes of depth-zero supercuspidal representations for simple adjoint groups, and check the bijectivity in various cases. We also prove that the Hiraga--Ichino--Ikeda conjecture on the formal degree of essentially square-integrable representations holds for this parametrization if it is bijective.
2025/07/01
Operator Algebra Seminars
16:45-18:15 Room #117 (Graduate School of Math. Sci. Bldg.)
Mao Hoshino (Univ. Tokyo)
A tensor categorical aspect of quantum group actions
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Mao Hoshino (Univ. Tokyo)
A tensor categorical aspect of quantum group actions
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
17:00-18:00 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Genki Sato (Fcuro, Inc.)
Presentation of finite Reedy categories as localizations of finite direct categories (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Genki Sato (Fcuro, Inc.)
Presentation of finite Reedy categories as localizations of finite direct categories (JAPANESE)
[ Abstract ]
In this talk, we present a novel construction that, for a given Reedy category $C$, produces a direct category $\operatorname{Down}(C)$ and a functor $\operatorname{Down}(C) \to C$, exhibiting $C$ as an $(\infty,1)$-categorical localization of $\operatorname{Down}(C)$. This result refines previous constructions in the literature by ensuring that $\operatorname{Down}(C)$ is finite whenever $C$ is finite—a property not guaranteed by existing approaches, such as those by Lurie or by Barwick and Kan. As an intended future application, this finiteness property is expected to be useful for embedding the construction into the syntax of a (non-infinitary) logic. In particular, I expect that the construction may be used to develop a meta-theory of finitely truncated simplicial types and other finite Reedy presheaves for homotopy type theory, thereby extending Kraus and Sattler's unfinished approach. This talk is based on arXiv:2502.05096.
[ Reference URL ]In this talk, we present a novel construction that, for a given Reedy category $C$, produces a direct category $\operatorname{Down}(C)$ and a functor $\operatorname{Down}(C) \to C$, exhibiting $C$ as an $(\infty,1)$-categorical localization of $\operatorname{Down}(C)$. This result refines previous constructions in the literature by ensuring that $\operatorname{Down}(C)$ is finite whenever $C$ is finite—a property not guaranteed by existing approaches, such as those by Lurie or by Barwick and Kan. As an intended future application, this finiteness property is expected to be useful for embedding the construction into the syntax of a (non-infinitary) logic. In particular, I expect that the construction may be used to develop a meta-theory of finitely truncated simplicial types and other finite Reedy presheaves for homotopy type theory, thereby extending Kraus and Sattler's unfinished approach. This talk is based on arXiv:2502.05096.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2025/06/30
Tokyo Probability Seminar
16:00-17:30 Room #126 (Graduate School of Math. Sci. Bldg.)
We are having teatime from 15:15 in the common room on the second floor. Please join us.
Hugo Da Cunha (Université Lyon 1)
Boundary effects in the Facilitated Exclusion Process
We are having teatime from 15:15 in the common room on the second floor. Please join us.
Hugo Da Cunha (Université Lyon 1)
Boundary effects in the Facilitated Exclusion Process
[ Abstract ]
The Facilitated Exclusion Process (FEP) is a model of stochastic interacting particle system whose dynamics is subject to kinetic constraints, leading to a phase transition at the critical density 1/2: under this threshold, the system is completely frozen. In recent years, the FEP has been extensively studied on the periodic setting, but in this talk I will consider it with boundary conditions. I will focus first on open boundaries, with particles reservoirs at both ends allowing creation/annihilation of particles. If time allows, I will also consider the case of closed boundaries, when there are impermeable walls at both ends.
At the macroscopic level, the boundary dynamics impose some boundary conditions on the PDE describing the hydrodynamic limit, that can be of different types (such as Dirichlet, Neumann or Robin). These boundary conditions are not standard as they differ from what is usually found in other exclusion processes, and this is due to the two-phased nature of FEP.
This talk is based on joint works with Clément Erignoux, Marielle Simon and Lu Xu.
The Facilitated Exclusion Process (FEP) is a model of stochastic interacting particle system whose dynamics is subject to kinetic constraints, leading to a phase transition at the critical density 1/2: under this threshold, the system is completely frozen. In recent years, the FEP has been extensively studied on the periodic setting, but in this talk I will consider it with boundary conditions. I will focus first on open boundaries, with particles reservoirs at both ends allowing creation/annihilation of particles. If time allows, I will also consider the case of closed boundaries, when there are impermeable walls at both ends.
At the macroscopic level, the boundary dynamics impose some boundary conditions on the PDE describing the hydrodynamic limit, that can be of different types (such as Dirichlet, Neumann or Robin). These boundary conditions are not standard as they differ from what is usually found in other exclusion processes, and this is due to the two-phased nature of FEP.
This talk is based on joint works with Clément Erignoux, Marielle Simon and Lu Xu.
2025/06/27
Infinite Analysis Seminar Tokyo
14:00-16:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Boris Feigin (Hebrew University)
W-algebra for supergroups, cosets and Langlands-type duality for supergroups
(English)
Boris Feigin (Hebrew University)
W-algebra for supergroups, cosets and Langlands-type duality for supergroups
(English)
[ Abstract ]
I try to explain what is known about the Langlands duality for superalgebras and also say something about center on a critical level for superalgebras.
I try to explain what is known about the Langlands duality for superalgebras and also say something about center on a critical level for superalgebras.
2025/06/26
Applied Analysis
16:00-17:30 Room #128 (Graduate School of Math. Sci. Bldg.)
Yang Yang (Johns Hopkins University)
A half-space Bernstein theorem for anisotropic minimal graphs (English)
Yang Yang (Johns Hopkins University)
A half-space Bernstein theorem for anisotropic minimal graphs (English)
[ Abstract ]
Anisotropic functionals are the natural generalization of the area functional. From a technical perspective, what distinguishes general anisotropic functionals from the area case is the absence of a monotonicity formula. In this talk, we will present a proof of a half-space Bernstein theorem for anisotropic minimal graphs with flat boundary condition. The proof uses only the maximal principle and ideas from fully nonlinear PDE theory in lieu of a monotonicity formula. This is joint work with W. Du, C. Moony, and J. Zhu.
Anisotropic functionals are the natural generalization of the area functional. From a technical perspective, what distinguishes general anisotropic functionals from the area case is the absence of a monotonicity formula. In this talk, we will present a proof of a half-space Bernstein theorem for anisotropic minimal graphs with flat boundary condition. The proof uses only the maximal principle and ideas from fully nonlinear PDE theory in lieu of a monotonicity formula. This is joint work with W. Du, C. Moony, and J. Zhu.
Tuesday Seminar on Topology
15:30-17:00 Room #hybrid/122 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Danny Calegari (The University of Chicago)
Universal circles and Zippers (2) (ENGLISH)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Danny Calegari (The University of Chicago)
Universal circles and Zippers (2) (ENGLISH)
[ Abstract ]
If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
[ Reference URL ]If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2025/06/24
Operator Algebra Seminars
16:45-18:15 Room #117 (Graduate School of Math. Sci. Bldg.)
George Elliott (Univ. Toronto)
Recent progress in the classification of $C^*$-algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
George Elliott (Univ. Toronto)
Recent progress in the classification of $C^*$-algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
17:00-18:30 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Danny Calegari (The University of Chicago)
Universal circles and Zippers (1) (ENGLISH)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Danny Calegari (The University of Chicago)
Universal circles and Zippers (1) (ENGLISH)
[ Abstract ]
If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
[ Reference URL ]If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2025/06/23
Seminar on Geometric Complex Analysis
10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Shoto Kikuchi (National Institute of Technology, Suzuka College)
Some properties of Azukawa pseudometrics for pluricomplex Green functions with poles along subvarieties (Japanese)
https://forms.gle/gTP8qNZwPyQyxjTj8
Shoto Kikuchi (National Institute of Technology, Suzuka College)
Some properties of Azukawa pseudometrics for pluricomplex Green functions with poles along subvarieties (Japanese)
[ Abstract ]
The Azukawa pseudometric is defined as the difference between the pluricomplex Green function and its logarithmic term along each complex lines passing through a pole. Therefore, the Azukawa pseudometric is useful to study the behavior of the pluricomplex Green function around a pole. It is also known that the Azukawa pseudometric is closely related to several important objects in complex analysis, including the Crath\'{e}odory-Reiffen pseudometric, the Kobayashi-Reiffen pseudometric, the Bergman kernel, among others.
In this talk, we present some properties and applications of an analogue of the Azukawa pseudometric for the pluricomplex Green function with poles along subvarieties.
If time permits, I will also explain my recent studies related to this topic.
[ Reference URL ]The Azukawa pseudometric is defined as the difference between the pluricomplex Green function and its logarithmic term along each complex lines passing through a pole. Therefore, the Azukawa pseudometric is useful to study the behavior of the pluricomplex Green function around a pole. It is also known that the Azukawa pseudometric is closely related to several important objects in complex analysis, including the Crath\'{e}odory-Reiffen pseudometric, the Kobayashi-Reiffen pseudometric, the Bergman kernel, among others.
In this talk, we present some properties and applications of an analogue of the Azukawa pseudometric for the pluricomplex Green function with poles along subvarieties.
If time permits, I will also explain my recent studies related to this topic.
https://forms.gle/gTP8qNZwPyQyxjTj8
2025/06/20
Colloquium
15:30-16:30 Room #大講義室(auditorium) (Graduate School of Math. Sci. Bldg.)
Yuichi Ike (Graduate School of Mathematical Sciences, The University of Tokyo)
The square peg problem and microlocal sheaf theory (JAPANESE)
Yuichi Ike (Graduate School of Mathematical Sciences, The University of Tokyo)
The square peg problem and microlocal sheaf theory (JAPANESE)
[ Abstract ]
The square peg problem asks whether every Jordan curve in the plane admits four distinct points that form the vertices of a square. This problem was proposed by Toeplitz in 1911, but it is still open. This problem can be generalized to the rectangular peg problem, which asks about the existence of a rectangle with a given aspect ratio. Greene and Lobb gave an affirmative answer to the rectangular peg problem for any smooth Jordan curve using symplectic geometry, and later improved the result using spectral invariants in Floer theory. In this talk, I will explain that we can solve the rectangular peg problem for any rectifiable Jordan curve using microlocal sheaf theory. This is joint work with Tomohiro Asano.
The square peg problem asks whether every Jordan curve in the plane admits four distinct points that form the vertices of a square. This problem was proposed by Toeplitz in 1911, but it is still open. This problem can be generalized to the rectangular peg problem, which asks about the existence of a rectangle with a given aspect ratio. Greene and Lobb gave an affirmative answer to the rectangular peg problem for any smooth Jordan curve using symplectic geometry, and later improved the result using spectral invariants in Floer theory. In this talk, I will explain that we can solve the rectangular peg problem for any rectifiable Jordan curve using microlocal sheaf theory. This is joint work with Tomohiro Asano.
Algebraic Geometry Seminar
13:30-15:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Fumiya Okamura (Chuo University)
Moduli spaces of rational curves on Artin-Mumford double solids
Fumiya Okamura (Chuo University)
Moduli spaces of rational curves on Artin-Mumford double solids
[ Abstract ]
Artin-Mumford double solids were originally constructed as examples of unirational but irrational varieties. Their method showed that the Brauer group gives an obstruction to rationality. Later, Voisin observed that this obstruction measures the difference between algebraic and numerical equivalence for 1-cycles.
In this talk, we study the moduli spaces of rational curves on Artin-Mumford double solids. First, we discuss the relation between the spaces of lines on these varieties and certain Enriques surfaces known as Reye congruences. Then, we classify all irreducible components of the moduli spaces of rational curves of each degree, and prove Geometric Manin's Conjecture in this setting.
Artin-Mumford double solids were originally constructed as examples of unirational but irrational varieties. Their method showed that the Brauer group gives an obstruction to rationality. Later, Voisin observed that this obstruction measures the difference between algebraic and numerical equivalence for 1-cycles.
In this talk, we study the moduli spaces of rational curves on Artin-Mumford double solids. First, we discuss the relation between the spaces of lines on these varieties and certain Enriques surfaces known as Reye congruences. Then, we classify all irreducible components of the moduli spaces of rational curves of each degree, and prove Geometric Manin's Conjecture in this setting.
2025/06/18
Number Theory Seminar
17:00-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)
Liu Yuanmin (University of Tokyo)
p-Adic cohomology over Laurent series rings and weight spectral sequences of strictly semistable schemes (日本語 (Japanese))
Liu Yuanmin (University of Tokyo)
p-Adic cohomology over Laurent series rings and weight spectral sequences of strictly semistable schemes (日本語 (Japanese))
[ Abstract ]
Let $k$ be a field of characteristic $p > 0$. Berthelot defined the rigid cohomology for varieties over $k$ after the work of Monsky-Washnitzer and Dwork. He also consider the theory of arithmetic D-modules which should be the coefficients for rigid cohomology. His work is generalized by Lazda-Pál and Caro to theories over $k((t))$. I will talk about their generalization and the construction of weight spectral sequence of strictly semistable schemes using arithmetic D-modules.
Let $k$ be a field of characteristic $p > 0$. Berthelot defined the rigid cohomology for varieties over $k$ after the work of Monsky-Washnitzer and Dwork. He also consider the theory of arithmetic D-modules which should be the coefficients for rigid cohomology. His work is generalized by Lazda-Pál and Caro to theories over $k((t))$. I will talk about their generalization and the construction of weight spectral sequence of strictly semistable schemes using arithmetic D-modules.
2025/06/17
Operator Algebra Seminars
16:45-18:15 Room #117 (Graduate School of Math. Sci. Bldg.)
Hikaru Awazu (University of Tokyo)
Amenability of group actions on compact spaces and the associated Banach algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Hikaru Awazu (University of Tokyo)
Amenability of group actions on compact spaces and the associated Banach algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
17:00-18:30 Room #ハイブリッド開催/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Taketo Sano (RIKEN iTHEMS)
A diagrammatic approach to the Rasmussen invariant via tangles and cobordisms (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Taketo Sano (RIKEN iTHEMS)
A diagrammatic approach to the Rasmussen invariant via tangles and cobordisms (JAPANESE)
[ Abstract ]
Rasmussen's s-invariant is an integer-valued knot invariant derived from Khovanov homology, and it has remarkable applications in topology, such as providing a combinatorial reproof of the Milnor conjecture. Although the s-invariant is defined using the quantum filtration of the homology group, it is difficult to interpret it geometrically. In this talk, we give a cobordism-based interpretation of the s-invariant based on Bar-Natan’s reformulation of Khovanov homology via tangles and cobordisms. This interpretation allows for the computation of the s-invariant from a tangle decomposition of the knot. As an application, we demonstrate that the s-invariants of a certain infinite family of pretzel knots can be determined by hand.
[ Reference URL ]Rasmussen's s-invariant is an integer-valued knot invariant derived from Khovanov homology, and it has remarkable applications in topology, such as providing a combinatorial reproof of the Milnor conjecture. Although the s-invariant is defined using the quantum filtration of the homology group, it is difficult to interpret it geometrically. In this talk, we give a cobordism-based interpretation of the s-invariant based on Bar-Natan’s reformulation of Khovanov homology via tangles and cobordisms. This interpretation allows for the computation of the s-invariant from a tangle decomposition of the knot. As an application, we demonstrate that the s-invariants of a certain infinite family of pretzel knots can be determined by hand.
Preprint: https://arxiv.org/abs/2503.05414
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2025/06/16
Seminar on Geometric Complex Analysis
10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Masakazu Takakura (Tokyo Metropolitan Univ.)
On the sharp $L^2$-estimate of Skoda division theorem (Japanese)
[ Reference URL ]
https://forms.gle/gTP8qNZwPyQyxjTj8
Masakazu Takakura (Tokyo Metropolitan Univ.)
On the sharp $L^2$-estimate of Skoda division theorem (Japanese)
[ Reference URL ]
https://forms.gle/gTP8qNZwPyQyxjTj8
2025/06/11
Lie Groups and Representation Theory
14:00-15:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Joint with FJ-LMI Seminar.
Valentina Casarino (University of Padua)
Variational inequalities in a nonsymmetric Gaussian framework (English)
Joint with FJ-LMI Seminar.
Valentina Casarino (University of Padua)
Variational inequalities in a nonsymmetric Gaussian framework (English)
[ Abstract ]
In this talk we introduce variation seminorms and consider the variation operator of a nonsymmetric Ornstein--Uhlenbeck semigroup (H_t)_(t> 0), taken with respect to t, in R^n. We prove that this seminorm defines an operator of weak type (1, 1) for the invariant measure.
The talk is based on joint work with Paolo Ciatti (University of Padua)and Peter Sjögren (Chalmers University).
In this talk we introduce variation seminorms and consider the variation operator of a nonsymmetric Ornstein--Uhlenbeck semigroup (H_t)_(t> 0), taken with respect to t, in R^n. We prove that this seminorm defines an operator of weak type (1, 1) for the invariant measure.
The talk is based on joint work with Paolo Ciatti (University of Padua)and Peter Sjögren (Chalmers University).
Discrete mathematical modelling seminar
17:00-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Andy Hone (University of Kent)
Quantum minimal surfaces and discrete Painlevé equations (English)
Andy Hone (University of Kent)
Quantum minimal surfaces and discrete Painlevé equations (English)
[ Abstract ]
We consider the quantum version of the Poisson bracket equations for a Riemann surface immersed as a minimal surface in 4D Euclidean space. For the case of the quantum parabola, we show that the equation for normalisation of states corresponds to a discrete Painlevé I equation (dP1). The condition that the norms should be positive yields a unique positive solution of the dP1, and by constructing the space of initial conditions we find that it corresponds to a sequence of classical solutions of Painlevé V, which we present explicitly in terms of ratios of modified Bessel functions and their Wronskians.
We consider the quantum version of the Poisson bracket equations for a Riemann surface immersed as a minimal surface in 4D Euclidean space. For the case of the quantum parabola, we show that the equation for normalisation of states corresponds to a discrete Painlevé I equation (dP1). The condition that the norms should be positive yields a unique positive solution of the dP1, and by constructing the space of initial conditions we find that it corresponds to a sequence of classical solutions of Painlevé V, which we present explicitly in terms of ratios of modified Bessel functions and their Wronskians.
Number Theory Seminar
17:00-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)
Bruno Kahn (FJ-LMI)
Zeta and $L$-functions of Voevodsky motives
https://webusers.imj-prg.fr/~bruno.kahn/
Bruno Kahn (FJ-LMI)
Zeta and $L$-functions of Voevodsky motives
[ Abstract ]
We associate an $L$-function $L^{\text{near}}(M,s)$ to any geometric motive over a global field $K$ in the sense of Voevodsky. This is a Dirichlet series which converges in some half-plane and has an Euler product factorisation. When $M$ is the dual of $M(X)$ for $X$ a smooth projective variety, $L^{\text{near}}(M,s)$ differs from the alternating product of the zeta functions defined by Serre in 1969 only at places of bad reduction; in exchange, it is multiplicative with respect to exact triangles. If $K$ is a function field over $\mathbb{F}_q$, $L^{\text{near}}(M,s)$ is a rational function in $q^{-s}$ and enjoys a functional equation. The techniques use the full force of Ayoub's six (and even seven) operations.
[ Reference URL ]We associate an $L$-function $L^{\text{near}}(M,s)$ to any geometric motive over a global field $K$ in the sense of Voevodsky. This is a Dirichlet series which converges in some half-plane and has an Euler product factorisation. When $M$ is the dual of $M(X)$ for $X$ a smooth projective variety, $L^{\text{near}}(M,s)$ differs from the alternating product of the zeta functions defined by Serre in 1969 only at places of bad reduction; in exchange, it is multiplicative with respect to exact triangles. If $K$ is a function field over $\mathbb{F}_q$, $L^{\text{near}}(M,s)$ is a rational function in $q^{-s}$ and enjoys a functional equation. The techniques use the full force of Ayoub's six (and even seven) operations.
https://webusers.imj-prg.fr/~bruno.kahn/
2025/06/10
Numerical Analysis Seminar
16:30-18:00 Room #002 (Graduate School of Math. Sci. Bldg.)
Nobuyuki Oshima (Faculty of Engineering, Hokkaido University)
Immersed-boundary Navier-Stokes equation and its application to image data (Japanese)
Nobuyuki Oshima (Faculty of Engineering, Hokkaido University)
Immersed-boundary Navier-Stokes equation and its application to image data (Japanese)
Tuesday Seminar on Topology
17:00-18:30 Room #ハイブリッド開催/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Takayuki Morifuji (Keio University)
Bell polynomials and hyperbolic volume of knots (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Takayuki Morifuji (Keio University)
Bell polynomials and hyperbolic volume of knots (JAPANESE)
[ Abstract ]
In this talk, we introduce two volume formulas for hyperbolic knot complements using Bell polynomials. The first applies to hyperbolic fibered knots and expresses the volume of the complement in terms of the trace of the monodromy matrix. The second provides a formula for the volume of general hyperbolic knot complements based on a weighted adjacency matrix. This talk is based on joint work with Hiroshi Goda.
[ Reference URL ]In this talk, we introduce two volume formulas for hyperbolic knot complements using Bell polynomials. The first applies to hyperbolic fibered knots and expresses the volume of the complement in terms of the trace of the monodromy matrix. The second provides a formula for the volume of general hyperbolic knot complements based on a weighted adjacency matrix. This talk is based on joint work with Hiroshi Goda.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Lie Groups and Representation Theory
15:30-16:30 Room #128 (Graduate School of Math. Sci. Bldg.)
Joint with FJ-LMI Seminar.
Paolo Ciatti (University of Padua)
Spectral estimates on the Heisenberg group (English)
Joint with FJ-LMI Seminar.
Paolo Ciatti (University of Padua)
Spectral estimates on the Heisenberg group (English)
[ Abstract ]
In this talk we will discuss some estimates concerning the spectral projections of the sub-Laplacian on the Heisenberg group. We will also consider some open problems and formulate a conjecture, providing some motivation for it.
In this talk we will discuss some estimates concerning the spectral projections of the sub-Laplacian on the Heisenberg group. We will also consider some open problems and formulate a conjecture, providing some motivation for it.
Algebraic Geometry Seminar
14:00-15:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Meng Chen (Fudan University)
Some new methods in estimating the lower bound of the canonical volume of 3-folds of general type
Meng Chen (Fudan University)
Some new methods in estimating the lower bound of the canonical volume of 3-folds of general type
[ Abstract ]
We introduce some new advance in estimating the lower bound of the canonical volume of 3-folds of general type with very small geometric genus. This topic covers a joint work with Jungkai A. Chen, Yong Hu and Chen Jiang.
We introduce some new advance in estimating the lower bound of the canonical volume of 3-folds of general type with very small geometric genus. This topic covers a joint work with Jungkai A. Chen, Yong Hu and Chen Jiang.
Algebraic Geometry Seminar
16:00-17:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Xun Yu (Tianjin University)
On the real forms of smooth complex projective varieties
Xun Yu (Tianjin University)
On the real forms of smooth complex projective varieties
[ Abstract ]
The real form problem asks how many different ways one can describe a given complex variety by polynomial equations with real coefficients, up to isomorphisms over the real number field. In this talk, I will discuss some recent results about real forms of smooth complex projective varieties. This talk is based on my joint works with T.-C. Dinh, C. Gachet, G. van der Geer, H.-Y. Lin, K. Oguiso, and L. Wang.
The real form problem asks how many different ways one can describe a given complex variety by polynomial equations with real coefficients, up to isomorphisms over the real number field. In this talk, I will discuss some recent results about real forms of smooth complex projective varieties. This talk is based on my joint works with T.-C. Dinh, C. Gachet, G. van der Geer, H.-Y. Lin, K. Oguiso, and L. Wang.
Tokyo-Nagoya Algebra Seminar
15:30-17:00 Online
Mohamad Haerizadeh (Univeristy of Tehran)
Generic decompositions of g-vectors (English)
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Mohamad Haerizadeh (Univeristy of Tehran)
Generic decompositions of g-vectors (English)
[ Abstract ]
In this talk, we discuss the role of g-vectors in the representation theory of algebras. Specifically, we describe how generic decompositions of g-vectors yield decompositions of generically τ-reduced components of representation varieties and vice versa. This connection allows us to provide a partial answer to the Cerulli-Labardini-Schröer conjecture concerning the number of direct summands of generically τ-reduced components of representation varieties.
Furthermore, we examine the cones of g-vectors, demonstrating that they are both rational and simplicial. We establish that g-vectors satisfy the ray condition if they are sufficiently far from the origin. These results enable us to generalize several results by Asai and Iyama concerning TF-equivalence classes of g-vectors. Therefore, our consequences can be utilized to study the wall and chamber structures of finite-dimensional algebras. This is joint work with Siamak Yassemi.
Zoom ID 844 4810 7612 Password 275169
[ Reference URL ]In this talk, we discuss the role of g-vectors in the representation theory of algebras. Specifically, we describe how generic decompositions of g-vectors yield decompositions of generically τ-reduced components of representation varieties and vice versa. This connection allows us to provide a partial answer to the Cerulli-Labardini-Schröer conjecture concerning the number of direct summands of generically τ-reduced components of representation varieties.
Furthermore, we examine the cones of g-vectors, demonstrating that they are both rational and simplicial. We establish that g-vectors satisfy the ray condition if they are sufficiently far from the origin. These results enable us to generalize several results by Asai and Iyama concerning TF-equivalence classes of g-vectors. Therefore, our consequences can be utilized to study the wall and chamber structures of finite-dimensional algebras. This is joint work with Siamak Yassemi.
Zoom ID 844 4810 7612 Password 275169
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
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