In this talk, we will look at mathematical modeling of language using computer simulations. Using these models, we study how individuals with language spread through a population of individuals without language. We consider a population without language on one- and two-dimensional grids. Language will appear in the population through a genetic mutation. To study how the language group will grow, we focus on the effects of talking and movement. If two individuals with language are next to each other on the grid, they can communicate.
Laver functions for supercompact cardinals appear in many forcing constructions, including all known constructions of models of strong forcing axioms. Viale proved that the Proper Forcing Axiom implies the existence of a "generic" Laver function from $\omega_2 \to H_{\omega_2}$. I will discuss his result and some recent work of mine on generic Laver functions.
I will discuss a sharp lower bound for the first positive eigenvalue of the sublaplacian on a closed, strictly pseudoconvex pseudo-hermitian manifold of dimension $2m+1\geq 5$. We prove that the equality holds iff the manifold is equivalent to the CR sphere up to a scaling. The essential step is a characterization of the CR sphere when there is a nonzero function satisfying a certain overdetermined system.
This is joint work with Song-Ying Li.
In this talk I will present some recent results concerning the
asymptotic self-similar patterns of degenerate diffusion in an infinite
porous medium with vanishing at infinity variable density.
The asymptotic pattern turns out to strongly depend on the decay rate of
the density. For "slowly" decaying densities, the picture is similar to
the homogeneous case (Barenblatt-type solutions), whereas for densities,
decaying fast enough, a completely different behavior, typical of problems
in bounded domains, arises.
For intermediate decay rates, both descriptions are correct, providing an
example of matched asymptotics.
Abstract: For the site percolation model on the triangular lattice and
certain generalizations for which Cardy’s Formula has been established
we acquire a power law estimate for the rate of convergence of the
crossing probabilities to Cardy’s Formula.
There does not exist closed manifold along the line of projective planes
above the dimension of octonions due to the inexistence of hopf invariant
1 map in higher dimensions. I investigated the existence dimension of such
manifold in the rational sense, such that the rational cohomology is rank
one in dimension 0, 2k and 4k and is zero otherwise. Applying rational
surgery, the problem can be reduced to finding possible Pontryagin classes
satisfying the Hirzebruch signature formula and a set of congruence relations
determined by the Riemann-Roch integrality conditions, which is eventually
equivalent to solving a system of Diophantine equations. After a negative
answer in dimension 24, the first existence dimension of such manifold is 32.
Ishlinsky Institute for Problems in Mechanics, RAS, Moscow, and Moscow Institute of Physics and Technology, Russia
Time:
Thursday, November 1, 2012 - 2:00pm
Location:
RH 340
Using as examples the Schroedinger equation and the wave equation we show that homogenization of many linear operators with oscillating coefficients could be done in a frame of the adiabatic approximation based on pseudodifferential operators (functions of noncommuting operators) and the Maslov methods. This approach allows one to reproduce well known homogenization results in the other way, but also take into account so-called dispersion effects leading to a change of structure of original equation. We discuss as example the asymptotic of the solution to the Cauchy problem with localized initial data and rapidly oscillating velocity.
This work was done together with J.Bruening, V.Grushin and S.Sergeev.