Activities This Week
Geometry in the Spring: a mini-conference on geometry
May 21, 11:00—18:00, 2019, Seminar room -101, Deichmann bldg. 58
Geometry in the Spring
Program:
11:00-11:30 Gathering and light refreshements
11:30-12:30 Ran Tessler (Weizmann Institute of Science), “The open arf invariant and stratifications of moduli spaces of surfaces with boundary”.
12:30-14:00 Lunch
14:00-16:15 Award ceremony in honor of Noriko Sakurai, Hillel Gauchman and Yossi Friedman.
- Honorary speaker: Sergey Fomin (University of Michigan, Ann Arbor), “Cluster Transformations”.
16:40-17:40 Eugenii Shustin (Tel Aviv University), TBA
Organizers:
- Prof. Miriam Cohen (Ben Gurion University),
- Prof. Daniel Sternheimer (Rikkyo University, Institut de Mathematiques de Bourgogne),
- Dr. Inna Entova-Aizenbud (Ben Gurion University).
The award ceremony will be held in the presence of Prof. Daniel Sternheimer and Ms. Julia Gauchman.
Award ceremony in honor of Noriko Sakurai, Hillel Gauchman and Yossi Friedman
May 21, 12:30—16:15, 2019, Seminar room -101, Deichmann bldg. 58
Colloquium
TBA
May 21, 14:30—15:30, 2019, Math -101
Speaker
Noriko Sakurai and Gauchman events. Speaker: Sergei Fomin
אשנב למתמטיקה
מה גורם למספר כרומטי של גרף להיות גדול?
May 21, 18:10—19:30, 2019, אולם 101-
Speaker
מנחם קוג'מן
Abstract
השאלה בכותרת היא שאלה עתיקה שאין לה תשובה פשוטה. משפט מסתורי של ארדש והיינל משנות החמישים מבטיח שבכל גרף בעל מספר כרומטי לא בן-מניה חייבים להימצא תת-גרפים דו-צדדיים גדולים. הדבר מוזר, כי לגרפים דו-צדדיים יש מספר כרומטי 2. נדון בהסבר למסתורין, המערב מספרים גדולים יותר מהמספר הכרומטי, נציג חלק מהקשרים בין המספרים האלה וגם נציג את השיטה שארדש והיינל השתמשו בה וניגע בגרסאות יותר מודרניות שלה שמשתמשות באריתמטיקה אינסופית חדשה יחסית.
AGNT
Morsifications and mutations
May 22, 15:10—16:25, 2019, -101
Speaker
Sergey Fomin (University of Michigan)
Abstract
I will discuss a somewhat mysterious connection between singularity theory and cluster algebras, more specifically between the topology of isolated singularities of plane curves and the mutation equivalence of quivers associated with their morsifications. The talk will assume no prior knowledge of any of these topics. This is joint work with Pavlo Pylyavskyy, Eugenii Shustin, and Dylan Thurston.
BGU Probability and Ergodic Theory (PET) seminar
On (a,b) Pairs in Random Fibonacci Sequences
May 23, 11:10—12:00, 2019, -101
Speaker
J.C. Saunders (Ben-Gurion University)
Abstract
| We deal with the random Fibonacci tree, which is an infinite binary tree with nonnegative integers at each node. The root consists of the number 1 with a single child, also the number 1. We define the tree recursively in the following way: if x is the parent of y, then y has two children, namely | x−y | and x+y. This tree was studied by Benoit Rittaud who proved that any pair of integers a,b that are coprime occur as a parent-child pair infinitely often. We extend his results by determining the probability that a random infinite walk in this tree contains exactly one pair (1,1), that being at the root of the tree. Also, we give tight upper and lower bounds on the number of occurrences of any specific coprime pair (a,b) at any given fixed depth in the tree. |