## Seminar information archive

Seminar information archive ～02/25｜Today's seminar 02/26 | Future seminars 02/27～

### 2005/07/22

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Szegö kernel の構成について

**倉西正武**(コロンビア大学)Szegö kernel の構成について

#### Seminar on Geometric Complex Analysis

15:30-17:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Effective Local Finite Generation of Multiplier Ideal Sheaves

**Dan Popovici**(JSPS, 名古屋大学多元数理)Effective Local Finite Generation of Multiplier Ideal Sheaves

### 2005/07/20

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

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**(島根大学)Equivalence between the boundary Harnack principle and the Carleson estimate

[ Abstract ]

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.

[ Reference 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

### 2005/07/13

#### PDE Real Analysis Seminar

10:30-11:30 Room #122 (Graduate School of Math. Sci. Bldg.)

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**(北海道大学)On classical solutions of the compressible Navier-Stokes equation with nonnegative density

[ Abstract ]

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.

[ Reference 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

### 2005/07/11

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

学習理論のゼータ関数と特異点解消

**青柳美輝**(上智大理工)学習理論のゼータ関数と特異点解消

### 2005/07/04

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Variation of Bergman kernel of projective manifolds

**辻 元**(上智大理工)Variation of Bergman kernel of projective manifolds

### 2005/06/27

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Uniqueness problem of analytic coverng spaces

**相原義弘**(沼津高専)Uniqueness problem of analytic coverng spaces

### 2005/06/22

#### Seminar on Mathematics for various disciplines

16:30-17:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Threshold Dynamics for the Piecewise Constant

http://coe.math.sci.hokudai.ac.jp/sympo/various/index.html

**Y. H. Richard Tsai**(University of Texas)Threshold Dynamics for the Piecewise Constant

[ Abstract ]

We propose an efficient algorithm for minimizing the piecewise constant Mumford-Shah functional of image segmentation. It is based on the threshold dynamics of Merriman, Bence, and Osher for evolving an interface by its mean curvature. We show that a very fast minimization can be achieved by alternating the solution of a linear parabolic partial differential equation and simple thresholding. We discuss our current work of extending this line of work to higher order accuracy and to applications involving Willmore flow.

[ Reference URL ]We propose an efficient algorithm for minimizing the piecewise constant Mumford-Shah functional of image segmentation. It is based on the threshold dynamics of Merriman, Bence, and Osher for evolving an interface by its mean curvature. We show that a very fast minimization can be achieved by alternating the solution of a linear parabolic partial differential equation and simple thresholding. We discuss our current work of extending this line of work to higher order accuracy and to applications involving Willmore flow.

http://coe.math.sci.hokudai.ac.jp/sympo/various/index.html

### 2005/06/15

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Singular and fractional integral operators on function spaces related to Morrey spaces

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**中井英一**(大阪教育大学)Singular and fractional integral operators on function spaces related to Morrey spaces

[ Abstract ]

It is known that the Hardy-Littlewood maximal operator, singular integral operators and fractional integral operators are bounded on L^p spaces and Morrey spaces. We extend the boundedness to generalized Morrey spaces, Orlicz-Morrey spaces, etc.

[ Reference URL ]It is known that the Hardy-Littlewood maximal operator, singular integral operators and fractional integral operators are bounded on L^p spaces and Morrey spaces. We extend the boundedness to generalized Morrey spaces, Orlicz-Morrey spaces, etc.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/06/08

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Weighted Hardy spaces on an interval and Jacobi series

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**宮地晶彦**(東京女子大学)Weighted Hardy spaces on an interval and Jacobi series

[ Abstract ]

For the classical Hardy class consisting of functions holomorphic in the unit disc, the Burkholder-Gundy-Silverstein theorem gives a characterization of the class in terms of certain maximal functions. We give a variant of this theorem related to weighted Hardy spaces on the interval(0,$\\pi$) and generalized holomorphic functions efined through ultraspherical (Gegenbauer) polynomials.

[ Reference URL ]For the classical Hardy class consisting of functions holomorphic in the unit disc, the Burkholder-Gundy-Silverstein theorem gives a characterization of the class in terms of certain maximal functions. We give a variant of this theorem related to weighted Hardy spaces on the interval(0,$\\pi$) and generalized holomorphic functions efined through ultraspherical (Gegenbauer) polynomials.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/06/06

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Application of Hartogs type extension theorems to Levi flats in Kaehler manifolds

**大沢健夫**(名大多元数理)Application of Hartogs type extension theorems to Levi flats in Kaehler manifolds

### 2005/06/01

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Annihilation of wave fronts of a reaction-diffusion equation

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**Jong-Shenq-Guo**(国立台湾師範大学)Annihilation of wave fronts of a reaction-diffusion equation

[ Abstract ]

We shall present some recent results on the existence and uniqueness of 2-front entire solutions of a reaction-diffusion equation. These entire solutions behave as two opposite wave fronts approaching each other from both sides of the x-axis and then annihilating in a finite time.

[ Reference URL ]We shall present some recent results on the existence and uniqueness of 2-front entire solutions of a reaction-diffusion equation. These entire solutions behave as two opposite wave fronts approaching each other from both sides of the x-axis and then annihilating in a finite time.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/05/30

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

全曲率有限な完備極小曲面のガウス写像の除外値について

**宮岡礼子**(九大数理)全曲率有限な完備極小曲面のガウス写像の除外値について

### 2005/05/25

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Some regularity results for Stefan equation

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

Nonlinear elliptic systems with general growth

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**Vincenzo Vespri**(Dipartimento di Matematica Ulisse Dini Viale Morgagni) 10:30-11:30Some regularity results for Stefan equation

[ Abstract ]

We consider the eqation $\\beta (u)_t = A(u)$ where $A$ is an elliptic operator and $\\beta$ is a maximal graph. Under suitable hypothesis on $\\beta$ and $A$ we prove the continuity of local solutions extendind some techniques introduced in the 80's.

[ Reference URL ]We consider the eqation $\\beta (u)_t = A(u)$ where $A$ is an elliptic operator and $\\beta$ is a maximal graph. Under suitable hypothesis on $\\beta$ and $A$ we prove the continuity of local solutions extendind some techniques introduced in the 80's.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**Paolo Marcellini**(Università degli Studi di Firenze) 11:45-12:45Nonlinear elliptic systems with general growth

[ Abstract ]

We prove \\textit{local Lipschitz-continuity} and, as a consequence, $C^{k}$%\\textit{\\ and }$C^{\\infty }$\\textit{\\ regularity} of \\textit{weak} solutions $u$ for a class of \\textit{nonlinear elliptic differential systems} of the form $\\sum_{i=1}^{n}\\frac{\\partial }{\\partial x_{i}}a_{i}^{\\alpha}(Du)=0,\\;\\alpha =1,2\\dots m$. The \\textit{growth conditions} on the dependence of functions $a_{i}^{\\alpha }(\\cdot )$ on the gradient $Du$ are so mild to allow us to embrace growths between the \\textit{linear} and the \\textit{exponential} cases, and they are more general than those known in the literature.

[ Reference URL ]We prove \\textit{local Lipschitz-continuity} and, as a consequence, $C^{k}$%\\textit{\\ and }$C^{\\infty }$\\textit{\\ regularity} of \\textit{weak} solutions $u$ for a class of \\textit{nonlinear elliptic differential systems} of the form $\\sum_{i=1}^{n}\\frac{\\partial }{\\partial x_{i}}a_{i}^{\\alpha}(Du)=0,\\;\\alpha =1,2\\dots m$. The \\textit{growth conditions} on the dependence of functions $a_{i}^{\\alpha }(\\cdot )$ on the gradient $Du$ are so mild to allow us to embrace growths between the \\textit{linear} and the \\textit{exponential} cases, and they are more general than those known in the literature.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/05/23

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

A-branes from CR-geometry

**赤堀隆夫**(兵庫県立大物質理学)A-branes from CR-geometry

### 2005/05/18

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

A model of damage evolution in viscous locking material.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**剣持信幸**(千葉大学)A model of damage evolution in viscous locking material.

[ Abstract ]

A model problem, describing the damage evolution for instance in some composite materials, is considered. The model is a system of nonlinear PDEs, which are kinetic equations for the displacement and damage quantity in the material. They are both heavily nonlinear parabolic equations, and one of them is of degenerate type. In this talk, the existence of a global in time solution is shown with some key ideas.

[ Reference URL ]A model problem, describing the damage evolution for instance in some composite materials, is considered. The model is a system of nonlinear PDEs, which are kinetic equations for the displacement and damage quantity in the material. They are both heavily nonlinear parabolic equations, and one of them is of degenerate type. In this talk, the existence of a global in time solution is shown with some key ideas.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/05/16

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Algebraic degeneracy of holomorphic curves

**野口潤次郎**(東大数理)Algebraic degeneracy of holomorphic curves

### 2005/05/09

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

レビ形式が退化する、あるクラスの実超曲面の定義関数について

**林本厚志**(長野高専)レビ形式が退化する、あるクラスの実超曲面の定義関数について

### 2005/04/25

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

停留的写像類群とタイヒミュラー空間への作用

**藤川英華**(東工大情報理工)停留的写像類群とタイヒミュラー空間への作用

### 2005/04/20

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Small modifications of quadrature domains around a cusp

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**酒井 良**(都立大学)Small modifications of quadrature domains around a cusp

[ Abstract ]

A flow which is produced by injection of fluid into the narrow gap between two parallel planes is called a Hele-Shaw flow. We regard the flow as an increasing family of plane domains and discuss the case that the initial domain has a cusp on the boundary. We give sufficient conditions for the cusp to be a laminar-flow point.

[ Reference URL ]A flow which is produced by injection of fluid into the narrow gap between two parallel planes is called a Hele-Shaw flow. We regard the flow as an increasing family of plane domains and discuss the case that the initial domain has a cusp on the boundary. We give sufficient conditions for the cusp to be a laminar-flow point.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/04/18

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

エネルギー有限な有理形関数の除外点の個数について

**厚地 淳**(慶大経済)エネルギー有限な有理形関数の除外点の個数について

### 2005/03/23

#### PDE Real Analysis Seminar

10:30-11:30 Room #122 (Graduate School of Math. Sci. Bldg.)

Pseudodifferential Boundary Value Problems with Non-Smooth Coefficients

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**Helmut Abels**(Max Planck Institute)Pseudodifferential Boundary Value Problems with Non-Smooth Coefficients

[ Abstract ]

We discuss an operator class that models elliptic differential boundary value problems as well as their solution operators and is closed under compositions. It was introduced by Boutet de Monvel in 1971 and provides a powerful tool to calculate with symbols associated to these operators. But the standard calculus and most of its further developments require that the symbols have smooth coefficient in the space and phase variable. We present some results which extend the calculus to symbols which have limited smoothness in the space variable. Such an extension is nescessary to apply the calculus to nonlinear partial differential boundary value problems and free boundary value problems.

[ Reference URL ]We discuss an operator class that models elliptic differential boundary value problems as well as their solution operators and is closed under compositions. It was introduced by Boutet de Monvel in 1971 and provides a powerful tool to calculate with symbols associated to these operators. But the standard calculus and most of its further developments require that the symbols have smooth coefficient in the space and phase variable. We present some results which extend the calculus to symbols which have limited smoothness in the space variable. Such an extension is nescessary to apply the calculus to nonlinear partial differential boundary value problems and free boundary value problems.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/03/02

#### PDE Real Analysis Seminar

10:30-11:30 Room #270 (Graduate School of Math. Sci. Bldg.)

The maximum principle in unbounded domains

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

Aubry set and applications

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**Italo Capuzzo-Dolcetta**(Universita di Roma) 10:30-11:30The maximum principle in unbounded domains

[ Abstract ]

The issue of the talk is the validity of the Weak Maximum Principle for functions u satisfying a second-order partial differential inequality of the form

(*) F(x,u,Du,D^2u) ≧ 0

in a domain A of the n-dimensional euclidean space.

The main result presented in the lecture is that for bounded above upper semicontinuous functions verifying

(*) in the viscosity sense, the inequality u≦ 0 on the boundary ∂A is propagated in the interior of the domain itself, under suitable conditions on F and A.

These conditions include ellipticity of F, a general geometric condition on the (possibly) unbounded domain A and a joint requirement involving the spread of A and the decay of first order terms at infinity.

This result, contained in I.C.D, A.Leoni, A.Vitolo "The Alexandrov-Bakelman-Pucci weak Maximum Principle for fully nonlinear equations in unbounded domains", to appear in Comm.in PDE's, extends previous results due to X.Cabré and L.Caffarelli-X.Cabré.

In the second part of the talk we present different versions of Weak Maximum Principle, namely for solutions growing exponentially fast of (*) in narrow domains and for solutions of

(**) F(x,u,Du,D^2u) + c(x)u ≧ 0

(c changing sign) in domains of small measure.

[ Reference URL ]The issue of the talk is the validity of the Weak Maximum Principle for functions u satisfying a second-order partial differential inequality of the form

(*) F(x,u,Du,D^2u) ≧ 0

in a domain A of the n-dimensional euclidean space.

The main result presented in the lecture is that for bounded above upper semicontinuous functions verifying

(*) in the viscosity sense, the inequality u≦ 0 on the boundary ∂A is propagated in the interior of the domain itself, under suitable conditions on F and A.

These conditions include ellipticity of F, a general geometric condition on the (possibly) unbounded domain A and a joint requirement involving the spread of A and the decay of first order terms at infinity.

This result, contained in I.C.D, A.Leoni, A.Vitolo "The Alexandrov-Bakelman-Pucci weak Maximum Principle for fully nonlinear equations in unbounded domains", to appear in Comm.in PDE's, extends previous results due to X.Cabré and L.Caffarelli-X.Cabré.

In the second part of the talk we present different versions of Weak Maximum Principle, namely for solutions growing exponentially fast of (*) in narrow domains and for solutions of

(**) F(x,u,Du,D^2u) + c(x)u ≧ 0

(c changing sign) in domains of small measure.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

**Antonio Siconolfi**(Universita di Roma) 11:45-12:45Aubry set and applications

[ Abstract ]

For given Hamiltonian H(x, p) continuous and quasiconvex in the second argument, defined in Rn × Rn or on the cotangent bundle of a compact boundaryless manifold, we consider the equation

H= c

with c critical value, i.e. for which the equation admits locally Lipschitzcontinuous a.e. subsolutions, but not strict subsolutions. We show that there is a subset of the state variable space, called Aubry set and denoted by A, where the obstruction to the existence of such subsolutions is concentrated. We give a metric characterization of A, and we discuss its main properties.

They are applied to a projection problem in a Banach space, to the study of the largetime behaviour of subsolutions to a timedependent HamiltonJacobi equation, and to construct a Lyapunov function for a perturbed dynamics, under suitable stability assumptions.

[ Reference URL ]For given Hamiltonian H(x, p) continuous and quasiconvex in the second argument, defined in Rn × Rn or on the cotangent bundle of a compact boundaryless manifold, we consider the equation

H= c

with c critical value, i.e. for which the equation admits locally Lipschitzcontinuous a.e. subsolutions, but not strict subsolutions. We show that there is a subset of the state variable space, called Aubry set and denoted by A, where the obstruction to the existence of such subsolutions is concentrated. We give a metric characterization of A, and we discuss its main properties.

They are applied to a projection problem in a Banach space, to the study of the largetime behaviour of subsolutions to a timedependent HamiltonJacobi equation, and to construct a Lyapunov function for a perturbed dynamics, under suitable stability assumptions.

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/01/26

#### PDE Real Analysis Seminar

10:30-11:30 Room #122 (Graduate School of Math. Sci. Bldg.)

L^p-Theory of the Navier-Stokes flow past rotating or moving obstacles

**Matthias Hieber**(ダルムシュタット工科大学)L^p-Theory of the Navier-Stokes flow past rotating or moving obstacles

[ Abstract ]

In this talk we consider the equation of Navier-Stokes in the exterior of a rotating or moving domain. Using techniques from the analysis of Ornstein-Uhlenbeck operators it is shown that, after rewriting the problem on a fixed domain $\\Omega$, the solution of the linearized equation is governed by a $C_0$-semigroup on $L^p_\\sigma(\\Omega)$ for $1

In this talk we consider the equation of Navier-Stokes in the exterior of a rotating or moving domain. Using techniques from the analysis of Ornstein-Uhlenbeck operators it is shown that, after rewriting the problem on a fixed domain $\\Omega$, the solution of the linearized equation is governed by a $C_0$-semigroup on $L^p_\\sigma(\\Omega)$ for $1

[ Reference URL ]

http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

### 2005/01/24

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Hausdorff measure and exceptional sets in Dirichlet space theory on local fields

**金子 宏**(東京理科大)Hausdorff measure and exceptional sets in Dirichlet space theory on local fields

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