# Colloquium

The weekly colloquium features a talk by an invited speaker. Topics vary and include all areas of mathematics.

The colloquium takes place on Tuesdays, 14:00 in room 614, 6’th floor of the Science and Education Building. For further details, please contact the colloquium coordinator, Dr. Oren Ben-Bassat.

## Colloquium: Tuesday, January 3, 2 pm. Speaker: Mikhail Borovoi (Tel Aviv). Title: “Reeder’s puzzle and orbits in real homogeneous spaces”.

In the talk I shall describe a puzzle for children. We have a pile of stones and a graph D with n vertices. At most one stone may be placed on a vertex, so a vertex has one of two…

## Colloquium: Tuesday, December 27, 12 pm. Speaker: Uriya First (UBC). Title: “Ramanujan Complexes”.

Ramanujan graphs are regular graphs whose vertex adjacency matrix has “very condensed” spectrum. The latter manifests in many desired combinatorial properties, most notable of which is the fact that Ramanujan graphs are expanders, i.e. they admit high connectivity among their…

## Colloquium: Tuesday, December 20, 2 pm. Speaker: Edva Roditty-Gershon (Bristol). Title: “Arithmetic statistics in function fields”.

In the talk I will discuss classical problems concerning the distribution of square-full numbers and their analogues over function fields. The results described are  in the context of the ring Fq[T] of polynomials over a finite field Fq of q elements,…

## Colloquium: Tuesday, December 6, 2 pm. Speaker: Tali Pinsky (Tata institute – India). Title: “Could the Lorenz flow be hyperbolic?”.

I will describe the theory of hyperbolic dynamical systems, and then describe a new approach to chaotic flows in dimension three, using knot theory. I’ll use this to show that, surprisingly, the famous Lorenz flow on R^3 can be related…

## Colloquium: Tuesday, November 29, 2 pm. Speaker: Boris Zilber (Oxford). Title: “A geometric semantics of algebraic quantum mechanics”.

We approach the formalism of quantum mechanics from the logician point of view and treat the canonical commutation relations and the conventional calculus based on it as an algebraic syntax of quantum mechanics. We then aim to establish a geometric…

## Colloquium: Tuesday, November 22, 2 pm. Speaker: Yehuda Pinchover (Technion). Title: “Some aspects of Hardy-type inequalities”.

: In 1921, Landau wrote a letter to Hardy including a proof of the inequality \begin{align*} \sum_{n=0}^{\infty}|\phi(n)-\phi(n+1)|^{p}\geq \left(\frac{p-1}{p}\right)^{p}\sum_{n=1}^{\infty}\frac{|\phi(n)|^{p}}{n^{p}} \end{align*} which holds for all finitely supported $\phi:\N_0\to\R$ such that $\phi(0)=0$ (here $1<p<\infty$ is a fixed number). This inequality was stated before…

## Colloquium: Tuesday, November 1, 2 pm. Speaker: Eitan Sayag (Ben Gurion). Title: “Spherical functions, spherical distributions and their applications”.

Periods of automorphic forms provides an important tool to classify automorphic representations and arise time and time again in problems with arithmetic origin. Motivated by that, I shall describe some of our investigation of local counterparts of these periods that…

## Colloquium: Tuesday, June 14, 2 pm. Speaker: Asaf Nachmias (Tel Aviv). Title: “The connectivity of the uniform spanning forest on planar graphs”.

The free uniform spanning forest (FUSF) of an infinite connected graph G is obtained as the weak limit of uniformly chosen spanning trees of finite subgraphs of G. It is easy to see that the FUSF is supported on spanning…

## Colloquium: Tuesday, June 7, 2 pm. Speaker: Jonathan Aaronson (Tel Aviv). Title: “Distributional limits of positive, ergodic stationary processes & infinite ergodic transformations”.

In infinite ergodic theory, distributional limits replace the absolutely normalized pointwise ergodic theorem.We’ll review the subject and then see that every random variable on the positive reals occurs as the distributional limit of some infinite ergodic transformation. We’ll consider consequences…

## Colloquium: Tuesday, May 31, 2 pm. Speaker: Dmitry Gourevitch (Weizmann). Title: “D-modules and equivariant distributions – old and new”.

I will first recall the notions of Schwartz functions and tempered distributions – on the line and then on general real affine algebraic manifolds. Then I will pose a problem on the existence of distributions that are semi-invariant under a…

Accessibility