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過去の記録 ～04/26｜本日 04/27 | 今後の予定 04/28～
2006年04月11日(火)
トポロジー火曜セミナー
16:30-18:00 数理科学研究科棟(駒場) 056号室
Tea: 16:00 - 16:30 コモンルーム
Martin Arkowitz 氏 (Dartmouth College)
Homotopy actions, cyclic maps and their Eckmann-Hilton duals.
Tea: 16:00 - 16:30 コモンルーム
Martin Arkowitz 氏 (Dartmouth College)
Homotopy actions, cyclic maps and their Eckmann-Hilton duals.
[ 講演概要 ]
We study the homotopy action of a based space A on a based space X. The resulting map A--->X is called cyclic. We classify actions on an H-space which are compatible with the H-structure. In the dual case we study coactions X--->X v B and the resulting cocyclic map X--->B. We relate the cocyclicity of a map to the Lusternik-Schnirelmann category of the map.
We study the homotopy action of a based space A on a based space X. The resulting map A--->X is called cyclic. We classify actions on an H-space which are compatible with the H-structure. In the dual case we study coactions X--->X v B and the resulting cocyclic map X--->B. We relate the cocyclicity of a map to the Lusternik-Schnirelmann category of the map.
2006年04月04日(火)
諸分野のための数学研究会
16:30-17:30 数理科学研究科棟(駒場) 128号室
Maria Reznikoff 氏 (Department of Mathematics, Princeton University)
Thermally-Driven Rare Events and Action Minimization
[ 参考URL ]
http://coe.math.sci.hokudai.ac.jp/sympo/various/004.html
Maria Reznikoff 氏 (Department of Mathematics, Princeton University)
Thermally-Driven Rare Events and Action Minimization
[ 参考URL ]
http://coe.math.sci.hokudai.ac.jp/sympo/various/004.html
2006年03月30日(木)
実解析セミナー
10:30-11:30 数理科学研究科棟(駒場) 118号室
Herbert Heyer 氏 (Tuebingen University)
Heyer教授特別講演会:Polynomial hypergroups of several variables
Herbert Heyer 氏 (Tuebingen University)
Heyer教授特別講演会:Polynomial hypergroups of several variables
2006年01月30日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
藤木 明 氏 (大阪大学)
Compact non-kaehler threefolds associated to hyperbolic 3-manifolds
藤木 明 氏 (大阪大学)
Compact non-kaehler threefolds associated to hyperbolic 3-manifolds
2006年01月23日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
金子 宏 氏 (東京理科大)
Stochastic processes and Besov spaces on local field
金子 宏 氏 (東京理科大)
Stochastic processes and Besov spaces on local field
2006年01月18日(水)
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 056号室
Juergen Saal 氏 (TU Darmstadt)
Analyticity of the interface of the classical two-phase Stefan problem
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
Juergen Saal 氏 (TU Darmstadt)
Analyticity of the interface of the classical two-phase Stefan problem
[ 講演概要 ]
The Stefan problem is a model for phase transitions in liquid-solid systems, as e.g. ice surrounded by water, and accounts for heat diffusion and exchange of latent heat in a homogeneous medium.
The strong formulation of this model corresponds to a free boundary problem involving a parabolic diffusion equation for each phase and a transmission condition prescribed at the interface separating the phases.
We prove that under mild regularity assumptions on the initial data the two-phase classical Stefan problem admits a unique solution that is analytic in space and time.
The result is based on $L_p$ maximal regularity for a linearized problem, which is proved first, and the implicit function theorem.
[ 参考URL ]The Stefan problem is a model for phase transitions in liquid-solid systems, as e.g. ice surrounded by water, and accounts for heat diffusion and exchange of latent heat in a homogeneous medium.
The strong formulation of this model corresponds to a free boundary problem involving a parabolic diffusion equation for each phase and a transmission condition prescribed at the interface separating the phases.
We prove that under mild regularity assumptions on the initial data the two-phase classical Stefan problem admits a unique solution that is analytic in space and time.
The result is based on $L_p$ maximal regularity for a linearized problem, which is proved first, and the implicit function theorem.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
2006年01月11日(水)
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 056号室
伊東 一文 氏 (North Carolina State University) 10:30-11:30
On Fluid Mechanics Formulation of Monge-Kantorovich Mass Transfer Problem
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
Oleg Yu. Imanuvilov 氏 (Colorado State University) 11:45-12:45
Local and Global Exact Controllability of Evolution Equations
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
伊東 一文 氏 (North Carolina State University) 10:30-11:30
On Fluid Mechanics Formulation of Monge-Kantorovich Mass Transfer Problem
[ 講演概要 ]
The Monge-Kantorovich mass transfer problem is equivalently formulated as an optimal control problem for the mass transport equation. The equivalency of the two problems is establish using the Lax-Hopf formula and the optimal control theory arguments. Also, it is shown that the optimal solution to the equivalent control problem is given in a gradient form in terms of the potential solution to the Monge-Kantorovich problem. It turns out
that the control formulation is a dual formulation of the Kantrovich distance problem via the Hamilton-Jacobi equations.
[ 参考URL ]The Monge-Kantorovich mass transfer problem is equivalently formulated as an optimal control problem for the mass transport equation. The equivalency of the two problems is establish using the Lax-Hopf formula and the optimal control theory arguments. Also, it is shown that the optimal solution to the equivalent control problem is given in a gradient form in terms of the potential solution to the Monge-Kantorovich problem. It turns out
that the control formulation is a dual formulation of the Kantrovich distance problem via the Hamilton-Jacobi equations.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
Oleg Yu. Imanuvilov 氏 (Colorado State University) 11:45-12:45
Local and Global Exact Controllability of Evolution Equations
[ 講演概要 ]
We discuss rcent global and local controlability results for the Navier-Stokes system and Bousinesq system. The control is acting on the part of the boundary or locally distributed over subdomain.
[ 参考URL ]We discuss rcent global and local controlability results for the Navier-Stokes system and Bousinesq system. The control is acting on the part of the boundary or locally distributed over subdomain.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
2005年12月05日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
Sebastien Boucksom 氏 (ParisVII / Univ. of Tokyo)
Positive cones of hyper-Keahler manifold
Sebastien Boucksom 氏 (ParisVII / Univ. of Tokyo)
Positive cones of hyper-Keahler manifold
2005年11月28日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
上田哲生 氏 (京都大学)
Schroeder equation and Abel equation
上田哲生 氏 (京都大学)
Schroeder equation and Abel equation
2005年11月22日(火)
諸分野のための数学研究会
16:30-17:30 数理科学研究科棟(駒場) 128号室
Hans Heesterbeek 氏 (University of Utrecht)
Mathematics in the epidemiology and control of infectious diseases
http://coe.math.sci.hokudai.ac.jp/sympo/various/index.html
Hans Heesterbeek 氏 (University of Utrecht)
Mathematics in the epidemiology and control of infectious diseases
[ 講演概要 ]
In this lecture I will give examples of the way in which mathematics helps in getting insight into the spread and control of infectious diseases. I will do this by discussing the population phenomena that are observed after an infectious agent enters a population (invasion, epidemic, recurrent epidemic, endemic, regulation, control). Along the way I will also give insight into the historical development of mathematical modelling in infectious disease epidemiology. Examples will be taken from human and animal infections. Special topics treated in some detail are threshold quantities such as the basic reproduction number R_0, the importance of understanding the structure of contacts in a population, the use of R_0 to estimate control effort with vaccines. In the last part of the lecture a number of important epidemiological problems will be discussed where input of new mathematical theory is needed.
[ 参考URL ]In this lecture I will give examples of the way in which mathematics helps in getting insight into the spread and control of infectious diseases. I will do this by discussing the population phenomena that are observed after an infectious agent enters a population (invasion, epidemic, recurrent epidemic, endemic, regulation, control). Along the way I will also give insight into the historical development of mathematical modelling in infectious disease epidemiology. Examples will be taken from human and animal infections. Special topics treated in some detail are threshold quantities such as the basic reproduction number R_0, the importance of understanding the structure of contacts in a population, the use of R_0 to estimate control effort with vaccines. In the last part of the lecture a number of important epidemiological problems will be discussed where input of new mathematical theory is needed.
http://coe.math.sci.hokudai.ac.jp/sympo/various/index.html
2005年11月21日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
Andreas Cap 氏 (Univ. of Vienna)
On CR-invariant differential operators
Andreas Cap 氏 (Univ. of Vienna)
On CR-invariant differential operators
[ 講演概要 ]
My talk will be devoted to questions about differential operators which are intrinsic to non--degenerate CR structures of hypersurface type. Restricting to the subclass of spherical CR structures, this question admits an equivalent formulation in terms of representation theory, which leads to several surprising consequences.
Guided by the ideas from representation theory and using the canonical Cartan connection which is available in this situation, one obtains a construction for a large class of such operators, which continues to work for non--spherical structures, and even for a class of almost CR structures. In the end of the talk I will discuss joint work with V. Soucek which shows that in the integrable case many of the operators obtained in this way form complexes.
My talk will be devoted to questions about differential operators which are intrinsic to non--degenerate CR structures of hypersurface type. Restricting to the subclass of spherical CR structures, this question admits an equivalent formulation in terms of representation theory, which leads to several surprising consequences.
Guided by the ideas from representation theory and using the canonical Cartan connection which is available in this situation, one obtains a construction for a large class of such operators, which continues to work for non--spherical structures, and even for a class of almost CR structures. In the end of the talk I will discuss joint work with V. Soucek which shows that in the integrable case many of the operators obtained in this way form complexes.
2005年11月14日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
Raphael Pong 氏 (Ohio State Univ)
New invariants for CR and contact manifolds
Raphael Pong 氏 (Ohio State Univ)
New invariants for CR and contact manifolds
[ 講演概要 ]
In this talk I will explain the construction of several new invariants for CR and contact manifolds as noncommutative residue traces of various geometric pseudodifferential projections. In the CR setting these operators arise from the ∂b-complex and include the Szegö projections. In the contact setting they stem from the generalized Szegö projections at arbitrary integer levels of Epstein-Melrose and from the contact complex of Rumin. In particular, we recover and extend recent results of Hirachi and Boutet de Monvel and answer a question of Fefferman.
In this talk I will explain the construction of several new invariants for CR and contact manifolds as noncommutative residue traces of various geometric pseudodifferential projections. In the CR setting these operators arise from the ∂b-complex and include the Szegö projections. In the contact setting they stem from the generalized Szegö projections at arbitrary integer levels of Epstein-Melrose and from the contact complex of Rumin. In particular, we recover and extend recent results of Hirachi and Boutet de Monvel and answer a question of Fefferman.
2005年11月09日(水)
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 056号室
藤田安啓 氏 (富山大学)
Asymptotic solutions and Aubry sets for Hamilton-Jacobi equations
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
藤田安啓 氏 (富山大学)
Asymptotic solutions and Aubry sets for Hamilton-Jacobi equations
[ 講演概要 ]
In this talk, we consider the asymptotic behavior of the viscosity solution of the Cauchy problem for the Hamilton-Jacobi equation $u_t + \\alpha x\\cdot Du + H(Du) =f(x)$ in ${\\rm I}\\!{\\rm R}^N \\times (0,\\infty)$, where $\\alpha$ is a positive constant and $H$ is a convex function on ${\\rm I} \\!{\\rm R}^N$. We show that, under some assumptions, $u(x,t) - ct - v(x)$ converges to $0$ locally uniformly in ${\\rm I}\\!{\\rm R}^N$ as $t \\to \\infty$, where $c$ is a constant and $v$ is a viscosity solution of the Hamilton-Jacobi equation $c + \\alpha x\\cdot Dv + H(Dv) = f(x)$ in ${\\rm I}\\!{\\rm R}^N$. A set in ${\\rm I}\\!{\\rm R}^N$, which is called the {\\it Aubry set}, gives a concrete representation of the viscosity solution $v$. We also discuss convergence rates of this asymptotic behavior. This is a joint work with Professors H. Ishii and P. Loreti.
[ 参考URL ]In this talk, we consider the asymptotic behavior of the viscosity solution of the Cauchy problem for the Hamilton-Jacobi equation $u_t + \\alpha x\\cdot Du + H(Du) =f(x)$ in ${\\rm I}\\!{\\rm R}^N \\times (0,\\infty)$, where $\\alpha$ is a positive constant and $H$ is a convex function on ${\\rm I} \\!{\\rm R}^N$. We show that, under some assumptions, $u(x,t) - ct - v(x)$ converges to $0$ locally uniformly in ${\\rm I}\\!{\\rm R}^N$ as $t \\to \\infty$, where $c$ is a constant and $v$ is a viscosity solution of the Hamilton-Jacobi equation $c + \\alpha x\\cdot Dv + H(Dv) = f(x)$ in ${\\rm I}\\!{\\rm R}^N$. A set in ${\\rm I}\\!{\\rm R}^N$, which is called the {\\it Aubry set}, gives a concrete representation of the viscosity solution $v$. We also discuss convergence rates of this asymptotic behavior. This is a joint work with Professors H. Ishii and P. Loreti.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
2005年11月07日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
難波誠 氏 (追手門学院大学)
Moduli of Galois coverings of the complex projective line
難波誠 氏 (追手門学院大学)
Moduli of Galois coverings of the complex projective line
2005年10月26日(水)
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 056号室
利根川吉廣 氏 (北海道大学)
On Mullins-Sekerka as singular limit of Cahn-Hilliard, some mathematical progress and open problems
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
利根川吉廣 氏 (北海道大学)
On Mullins-Sekerka as singular limit of Cahn-Hilliard, some mathematical progress and open problems
[ 講演概要 ]
The Cahn-Hilliard equation and its variants have been widely used in materials science community to model coarse graining phenomena in mesoscopic scale. The equation has a parameter corresponding the order of thickness of phase boundaries. When the parameter is close to zero, the phase boundary and the chemical potential field are known to evolve by the so-called Mullins-Sekerka problem. The rigorous justification for the latter statement is known only for short-time so far. I describe some recent progress as well as some difficulties on the long-time case, relateing my recent works and those by M. Roeger and R. Schaetzle.
[ 参考URL ]The Cahn-Hilliard equation and its variants have been widely used in materials science community to model coarse graining phenomena in mesoscopic scale. The equation has a parameter corresponding the order of thickness of phase boundaries. When the parameter is close to zero, the phase boundary and the chemical potential field are known to evolve by the so-called Mullins-Sekerka problem. The rigorous justification for the latter statement is known only for short-time so far. I describe some recent progress as well as some difficulties on the long-time case, relateing my recent works and those by M. Roeger and R. Schaetzle.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
2005年10月24日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
平地健吾 氏 (東大数理)
Ambient metrics for even dimensional conformal structures
平地健吾 氏 (東大数理)
Ambient metrics for even dimensional conformal structures
2005年10月18日(火)
諸分野のための数学研究会
16:30-17:30 数理科学研究科棟(駒場) 128号室
Rainer Kress 氏 (Goettingen 大学)
Hybrid methods for inverse boundary problems
[ 参考URL ]
http://coe.math.sci.hokudai.ac.jp/sympo/various/index.html
Rainer Kress 氏 (Goettingen 大学)
Hybrid methods for inverse boundary problems
[ 参考URL ]
http://coe.math.sci.hokudai.ac.jp/sympo/various/index.html
2005年10月17日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
吉川謙一 氏 (東大数理)
On the discriminant of certain K3 surfaces
吉川謙一 氏 (東大数理)
On the discriminant of certain K3 surfaces
2005年09月28日(水)
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 056号室
Matthias Geissert 氏 (ダルムシュタット工科大学)
The Navier-Stokes flow in the exterior of a rotating obstacle
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
Matthias Geissert 氏 (ダルムシュタット工科大学)
The Navier-Stokes flow in the exterior of a rotating obstacle
[ 講演概要 ]
We show the existence of solutions of the Navier-Stokes flow in the exterior of a rotating obstacle. In the first step we transform the Navier-Stokes equations to a problem in a time independent domain. In this talk we present two different change of coordinates to do this. Finally, we discuss the advantages of both approaches and show the local existence and uniqueness of mild and strong $L^p$ solutions.
[ 参考URL ]We show the existence of solutions of the Navier-Stokes flow in the exterior of a rotating obstacle. In the first step we transform the Navier-Stokes equations to a problem in a time independent domain. In this talk we present two different change of coordinates to do this. Finally, we discuss the advantages of both approaches and show the local existence and uniqueness of mild and strong $L^p$ solutions.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
2005年07月22日(金)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
倉西正武 氏 (コロンビア大学)
Szegö kernel の構成について
倉西正武 氏 (コロンビア大学)
Szegö kernel の構成について
複素解析幾何セミナー
15:30-17:00 数理科学研究科棟(駒場) 128号室
Dan Popovici 氏 (JSPS, 名古屋大学多元数理)
Effective Local Finite Generation of Multiplier Ideal Sheaves
Dan Popovici 氏 (JSPS, 名古屋大学多元数理)
Effective Local Finite Generation of Multiplier Ideal Sheaves
2005年07月20日(水)
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 056号室
相川弘明 氏 (島根大学)
Equivalence between the boundary Harnack principle and the Carleson estimate
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
相川弘明 氏 (島根大学)
Equivalence between the boundary Harnack principle and the Carleson estimate
[ 講演概要 ]
Both the boundary Harnack principle and the Carleson estimate describe the boundary behavior of positive harmonic functions vanishing on a portion of the boundary. These notions are inextricably related and have been obtained simultaneously for domains with specific geometrical conditions. The main aim of this talk is to show that the boundary Harnack principle and the Carleson estimate are equivalent for arbitrary domains.
[ 参考URL ]Both the boundary Harnack principle and the Carleson estimate describe the boundary behavior of positive harmonic functions vanishing on a portion of the boundary. These notions are inextricably related and have been obtained simultaneously for domains with specific geometrical conditions. The main aim of this talk is to show that the boundary Harnack principle and the Carleson estimate are equivalent for arbitrary domains.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
2005年07月13日(水)
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 122号室
Yonggeun Cho 氏 (北海道大学)
On classical solutions of the compressible Navier-Stokes equation with nonnegative density
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
Yonggeun Cho 氏 (北海道大学)
On classical solutions of the compressible Navier-Stokes equation with nonnegative density
[ 講演概要 ]
In this talk, we discuss a recent progress on the regularity of solution of compressible Navier-Stokes equations with nonnegative density. The nonnegativity of density cauases a problem in using the usual parabolicity of momentum equations and hence in general makes it hard to gain a regularity of solution. To overcome the difficulty, we develop a natural compatibility condition. Then observing a smoothing effect for positive time, we obtain classical solutions of the compressible Navier-Stokes equations.
[ 参考URL ]In this talk, we discuss a recent progress on the regularity of solution of compressible Navier-Stokes equations with nonnegative density. The nonnegativity of density cauases a problem in using the usual parabolicity of momentum equations and hence in general makes it hard to gain a regularity of solution. To overcome the difficulty, we develop a natural compatibility condition. Then observing a smoothing effect for positive time, we obtain classical solutions of the compressible Navier-Stokes equations.
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html
2005年07月11日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
青柳美輝 氏 (上智大理工)
学習理論のゼータ関数と特異点解消
青柳美輝 氏 (上智大理工)
学習理論のゼータ関数と特異点解消
2005年07月04日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 128号室
辻 元 氏 (上智大理工)
Variation of Bergman kernel of projective manifolds
辻 元 氏 (上智大理工)
Variation of Bergman kernel of projective manifolds
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