We study some problems relating to polynomials evaluated either at random Gaussian or random Bernoulli inputs. We present a structure theorem for degree-d polynomials with Gaussian inputs. In particular, if p is a given degree-d polynomial, then p can be written in terms of some bounded number of other polynomials q_1,...,q_m so that the joint probability density function of q_1(G),...,q_m(G) is close to being bounded. This says essentially that any abnormalities in the distribution of p(G) can be explained by the way in which p decomposes into the q_i. We then present some applications of this result.
Eigenfunctions of the Laplacian on a bounded domain represent the modes of vibration of a vibrating drum. The behavior of these eigenfunctions is closely related to the behavior of the underlying dynamical system of the billiard table. In this talk I first give a brief exposition on this relation and then I talk about the boundary traces of eigenfunctions and a recent joint work with Han, Hassell and Zelditch.
I will outline a construction of an exotic solution of the nonlinear
Schrödinger equation that exhibits a big frequency cascade. Recent advances
related to this construction and some open questions will be surveyed.
Eigenfunctions of the Laplacian on a bounded domain represent the modes of vibration of a vibrating drum. The behavior of these eigenfunctions is closely related to the behavior of the underlying dynamical system of the billiard table. In this talk I first give a brief exposition on this relation and then I talk about the boundary traces of eigenfunctions and a recent joint work with Han, Hassell and Zelditch.
Finite subgroup of Cremona group is a classical topic in algebraic geometry since the 19th century. In this talk we explain an extension of this problem to the symplectic category. In particular, we will explain the symplectic counterparts of two classical theorems. The first one due to Noether, says a plane Cremona map is decomposed into a sequence of quadratic transformations, which is generalized to the symplectic category on the homological level. The second one is due to Castelnuovo and Kantor, which says a minimal G-surface either has a conic bundle structure or is a Del Pezzo surface. The latter theorem lies the ground of classifications of finite Cremona subgroups due to Dolgachev and Iskovskikh. This is an ongoing program joint with Weimin Chen and Tian-Jun Li
In this talk, I will give a brief summary of my current research projects with open problems for students interested in Ph.D. thesis research. These projects are principally in the areas of tissue pattern formation in developmental biology and genetic instability in carcinogenesis. Some details will be given to show the nature of the mathematical and computational problems involved.
The Hamiltonians of two and three particles moving on d-dimensional lattice and interacting via pairwise short-range potentials are studied.
The following new results are established:
(i).The existence of eigenvalues for the two-particle Shr\"odinger operators depending on the quasi-momentum.
(ii). Infiniteness the number of eigenvalues(Efimov's effect) of the three-particle Shr\"odinger operators
for the zero value of quasi-momentum and its finiteness for the non-zero values of the quasi-momentum.
(iii).The corresponding asymptotics for the number of eigenvalues.