Eventss

2020 Jun 02

Dynamics seminar : Rhiannon Dougall (Bristol) Critical exponents for subgroups of isometries of negatively curved spaces

2:00pm to 3:00pm


Abstract: One of the first things we learn about a (proper) Gromov hyperbolic geodesic space X is the construction of the visual boundary of X. An ergodic theorist then learns that for a non-elementary discrete group of isometries G acting properly on X, there is an interesting family of \delta_G-quasi-conformal measures on the boundary. The parameter \delta_G is called the critical exponent of G, and is equal to the exponential growth rate of the orbit Gx in X.
2020 Jun 29

Combinatorics: Dan Hefez (Ariel)

11:00am to 1:00pm

In this talk we will study the so-called perturbed model which is a graph distribution of the form G \cup \mathbb{G}(n,p), where G is an n-vertex graph with edge-density at least d > 0, and d is independent of n.

We are interested in the threshold of the following anti-Ramsey property: every proper edge-colouring of G \cup \mathbb{G}(n,p) yields a rainbow copy of K_s. We have determined this threshold for every s.   

Based on joint work with Elad Aigner-Horev, Oran Danon and Shoham Letzter.

2020 Jun 08

Combinatorics: Bannai Eiichi (Kyushu University)

11:00am to 12:45pm

Location: 

Zoom

Speaker: Bannai Eiichi (Kyushu University)

Title:
On unitary t-designs


Abstract: 

The purpose of design theory is for a given space $M$ to find good finite subsets $X$ of $M$ that approximate the whole space $M$ well. There are many design theories for various spaces $M$. If $M$ is the sphere $S^{n-1}$ then such $X$ are called spherical designs. If $M$ is the unitary group $U(d)$, then such $X$ are called unitary designs. 
2020 May 11

Combinatorics: Michael Krivelevich (TAU)

11:00am to 12:45pm

Location: 

Zoom

Speaker: Michael Krivelevich, Tel Aviv University
Title: Embedding large minors in weak expanders and in sparse random graphs

                         ABSTRACT

A graph G on n vertices is called an alpha-expander if the external neighborhood of every vertex subset U of size |U|<=n/2 in G has size at least alpha*|U|.
2020 May 10

ZOOM-IN מפגש התעניינות לתואר ראשון במתמטיקה

2:00pm to 3:00pm

Location: 

Zoom

זום-אין אל העתיד....שלך!
בואו למפגשי מתעניינים באוניברסיטה העברית ותעשו זום-אין על כל מסלולי הלימוד, המרצים והאוניברסיטה. 10 – 11 במאי.
ההרשמה באתר

מפגש ההתעניינות ב-ZOOM לתואר ראשון במתמטיקה יהיה ב-10.5.2020 בשעה 14:00
נשמח לראותך!

לפרטים נוספים

 

2020 May 06

Logic Seminar - Timo Krisam

11:00am to 1:00pm

Location: 

Zoom: Meeting ID: 959 8849 6874 , Password: 020269
Timo Krisam will speal about distal theories and the type decomposition theorem.
.
Title: Distal Theories and the Type Decomposition Theorem

Abstract: The class of NIP-Theories is an important subject of study in pure model theory. It contains many interesting examples like stable theories, o-minimal theories or algebraically closed valued fields.

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