Seminar

Title: Graph covers with two new eigenvalues

Abstract:

I am going to talk about graph covers. If $Y$ is a cyclic cover of $X$, it turns out that $Y$ has the same spectrum as $X$ plus (possibly) some new eigenvalues. 

Title: OutFn, M_gn and renormalized topological field theory

Abstract:

I will report on recent joint work with Karen Vogtmann on the Euler characteristic of Out(F_n) and the moduli space of graphs.

Title: How can we optimize nonsmooth objectives globally?

Abstract:

In machine learning objective functions that are only piecewise smooth and should be globally minimized abound. The standard method of dealing with them is to apply a stochastic gradient method disregarding the rare points of nonsmoothness and hoping for the best as far as global optimality of the computed solution is concerned.

Title: Biometric security: Design, implementation, and challenges

Abstract:

Biometric based cybersecurity technologies offer significant advantages in authentication, identification, and access control mechanisms.

Title: Inverses of Trees

Abstract:

A tree is invertible if and only if it has a perfect matching.

Godsil considers an invertible tree T and finds that the inverse of the adjacency matrix has entries in {0, ±1} and is the signed adjacency matrix of a graph which contains T.

Title: Incompressibility of classical distributions

Abstract:

We prove a general, robust, single-letter lower bound on the achievable rate for ensembles of classical states, which holds even when Alice and Bob share free entanglement and allow a constant local error. 

Title: Resilience of the rank of random matrices

Abstract:

I will discuss the preprint of this title by Ferber, Luh, and McKinley (arXiv:1910.03619).

Title: Disjunctive Cuts through the V-Polyhedral Lens

Abstract:

Cutting planes, or cuts, are a critical component of modern integer programming solvers, but existing cuts implemented in solvers are relatively simple compared to those in the literature. We discuss the primary reasons for this disparity, as well as our recently-proposed V-polyhedral framework for mitigating some of these difficulties encountered by prior "stronger" cuts.

Title: Kummer's Theorem on binomial coefficients, etc.

Abstract: 

Some of us like the primes and call ourselves pure mathematicians. Some of us like the Catalan numbers and call ourselves combinatorialists.

Title: Submodular function maximization via the multilinear relaxation and contention resolution schemes

Abstract:

I will present a general framework for maximizing a nonnegative submodular set function $f$ subject to a variety of packing type constraints including multiple matroid constraints, knapsack constraints, and their intersections.