Let G be a simple algebraic group over a field of positive characteristic, B a Borel subgroup of G, and F the Frobenius morphism on the flag variety B = G/B. A splitting of the comorphismF#:OB→F*OB via a→ap, due to Mehta and Ramanathan, marked a breakthrough in the study of the geometry of B regardless of characteristic. We will describe a construction of a splitting of the Frobenous morphism on the algebra of distributions Dist G on G. This is joint work with Michel Gros.

多复变与复几何系列学术报告(TJ-Seminar on Several Complex Variables and Complex Geometry)演讲人: 符斯奇教授（Rutgers大学）题目：Spectrum of the d-bar-Neumann Laplacian时间：2008年1月15日 数学系106室 3：30-5：00 p. m.地点：数学系106室欢迎大家参

报告人：华东师范大学数学系 舒斌教授题 目：Modular Representations of Supergroups时 间：2008年3月24日星期一下午3:30—5:00地 点：数学系致远楼106室欢迎各位参加

In an evolution model, a constant equilibrium is often stable if the perturbation is also constant one, hence it is dynamically stable with respect to an ODE dynamics. More realistic models often include the effect of spatial dispersal. In classicalTuring reaction- diffusion model, an instability is caused by diffusion with different diffusion coefficients, and it generates non-constant equilibria via bifurcation. In a model with attractive and repulsive chemotaxis, and another model with advection, we show that instability of a constant equilibrium can be caused by advection or chemotaxis. In both cases, Hopf bifurcations occur so oscillatory states emerge as the result of instability. The talk is based on joint work with Ping Liu, Zhian Wang, and Jun Zhou.

I will give a brief introduction of delayed differential equations, and show that the question of stability of an equilibrium solution is equivalent to an algebraic equation with transcendental terms. Then I will show the new method of solving the purely imaginary eigenvalues of a transcendental characteristic equation with two transcendental terms. The results are applied to the stability and associated Hopf bifurcation of a constant equilibrium of a generalreaction-diffusion system or ordinary differential equation with delay effects. Examples from chemical reaction and predator-prey models are analyzed using the new techniques. In particular the stability and associate Hopf bifurcation of a Gierer-Meinhardt system with the gene expression time delays is analyzed by using our method. This is a joint work with Shanshan Chen, and Junjie Wei.

报告人：张根凯教授张根凯教授报告题目一：Determinant of Toeplitiz operators on bounded symmetric domains and their Dixmier trace报告一时间：2013年7月3号上午9：00-10:15地点：致远楼107报告题目二：Estimates of normal differentiation of spherical harmonics along subsphere and complementary series of SO(n, 1).报告二时间：2013年7月3号上午10:30-11:45地点：致远楼107张根凯教授简介：张根凯教授，瑞典 Chalm...

In many situations, Business processes are often constrained by scarce resources. The lack of resources can cause contention among tasks and slow down the accomplishment of larger goals. This presentation discusses a Petri net based approach for recourse requirements analysis, which can be used for more general purposes. The concept of resource- oriented workflow nets (ROWN) is introduced and the transition firing rules of ROWN are presented. Resource requirements for general workflow can be done through reachability analysis. For a class of well-structured workflows, an efficient resource analysis algorithm is developed. Task falures are also considered in resource requirement analysis.

报告人：王维克教授(上海交通大学)报告题目： 数学的抽象时间：2013年7月4日（周四）下午4：00—5：00地点：数学系致远楼10