How many real zeroes does a random polynomial haveĀ ? (Talk 1)

Seminar: 
Combinatorics Seminar
Event time: 
Friday, September 13, 2013 - 10:00am to 11:00am
Location: 
215 LOM
Speaker: 
Van Vu
Speaker affiliation: 
Yale
Event description: 

Consider a polynomial $P_n =c_0 + c_1x +…c+n x$ of degree $n$ whose coefficients $c_i$ are real random variables. The problem of determining $N_n$, the number of real zeroes of $P_n$ goes back to Waring (1789), and has become popular since the work of Bloch-Polya and Littlewood-Offord in the 1940s. Deep works of Littlewood-Offord, Erdos-Offord, Kac, Stevens, Ibragimov-Maslova, Edelman-Kostlan, and many others give us a good understanding of $N_n$ in the case $c_i$ are iid random variables with mean $0$ and variance $1$ (see John Baez’s Lord of the Ring beautiful picture on http://math.ucr.edu/home/baez/). However, much less is known for the all other cases, when the $c_i$ have different variances and/or are dependent (a good example is the characteristic polynomial of a random matrix).

In this talk, I am going to give a brief survey on the state of the art of the problem, and introduce a new approach that will lead to the solution for a general set of random variables $c_i$. In the next talk, I will describe the main ideas behind the proof.

Joint work with T. Tao.