トップ   一覧 単語検索 最終更新   ヘルプ   最終更新のRSS
***** 専攻談話会(セミナー) [#t67d9871]



**第4回 [#v136b20a]

日時: ''2010年1月15日(金) 16:30 - 17:30''

会場: ''西8号館W棟10階W1008号室''

講演者: ''Wei-Ming Ni 氏(客員教授,University of Minnesota)''


要旨: In this talk I will discuss and compare the following two aspects of the dynamics of 2x2 reaction-diffusion equations and their shadow systems: global existence/finite-time blow-up, and, stability properties of steady states. A well known activator-inhibitor system in morphogenesis developed by Alan Turing , and A. Gierer and H. Meinhardt, will be used as a primary example to illustrate the results.

**第3回 [#kbd5e04e]

日時:   ''2009年11月25日(水) 16:30 - 17:30''

会場:   ''西8号館W棟10階W1008号室''

講演者:  ''Hans D. Mittelmann 氏 (Arizona State University)''

題目:   ''The Power of SDP Relaxations --- Computing Strong Bounds for QAPs and Graph Problems''

As is well-known semidefinite relaxations of discrete optimization
problems yield excellent bounds on their solutions. We present two
examples from our recent research. The first addresses the quadratic
assignment problem and a formulation is developed which yields the
strongest lower bounds known for a number of large cases (up to
dimension 256). It utilizes standard SDP software. With iterative
SDP solvers still larger dimensions as they occur, for example,
in communications, are within reach. The second area is the
computation of bounds in graph problems, respectively in geometry.
A strategy based on the Lovasz theta function is generalized to
compute lower bounds for the chromatic number of graphs and upper
bounds on the spherical kissing number utilizing SDP relaxations.
Multiple precision SDP solvers are needed and improvements on known
results for kissing numbers in dimensions up to 23 are obtained.

**第2回 [#q938586b]

日時:   ''2009年6月3日(水) 13:30 - 14:30''

会場:   ''西8号館W棟10階W1008号室''

講演者: ''Joseph Maher 氏 (Oklahoma State University)''

題目:   ''Surfaces, groups and random walks.''


Every group has an intrinsic geometry associated with it, which can help us understand properties of the group, such as:
- what does the group looks like on the large scale?
- what properties does a generic group element have?

We will consider such questions for various families of groups, such as free  groups, matrix groups, and groups arising from the study of surfaces, and we will mention some applications to 3-manifolds. 

**第1回 [#k8e2f936]

日時: ''2009年5月7日(木) 13:20-''

会場: ''西8号館W棟8階W809号室''

講演者:	''Karl Sigman 氏 (Columbia University)''

題目: ''Brief introduction to Monte Carlo Simulation and its use for estimating the price of simple stock options (under the Binomial Lattice Model)''

**過去の談話会 [#db336cc6]