### האירועים האחרונים

• The HUJI-BGU Workshop in Arithmetic Jan 13, 10:30-16:15, 2020.

10.30 - 11.00 Welcome

11.00 - 11:50 Francesco Saettone (BGU), Analytic continuation of L-functions of characters: Tate‘s thesis.

12.05 - 12.55 Zev Rosengarten (HUJI), L-functions of characters and regulators: Beilinson‘s conjecture.

14.15 - 15.05 Amnon Besser (BGU), The p-adic Beilinson conjectures for number fields.

15.20 -16.00 Yotam Svoray (BGU), Polylogarithms and their geometry.

16.00 -16.15 (bonus content): Ishai Dan-Cohen (BGU) Regulators are polylogarithms.

All talks in room -101.

• האריה המתמטי: יום עיון לקהל מתמטי רחב Oct 24, 09:30-18:00, 2019, אוניברסיטת בן-גוריון בנגב (קמפוס ע"ש משפחת מרקוס), בניין 26, אולם 5.

הנכם מוזמנים ליום עיון ”האריה המתמטי“ באוניברסיטת בן-גוריון בנגב. יום העיון יכיל 6 הרצאות בנושאים שונים במתמטיקה, המיועדות לקהל מתמטי רחב. תכנית מפורטת של יום העיון, כולל תקצירי הרצאות ודרישות קדם לכל הרצאה, תופיע באתר האירוע. מחכים לכם!

המרצים:

• דור אלימלך

• גילי גולן

• איליה טיומקין

• אריאל ידין

• מנחם קוג‘מן

• לירן רון

• Department picnic Oct 20, 11:00-16:00, 2019, Amphitheater, Ashkelon National Park.

You are cordially invited to a “beginning-of-the-year” informal picnic/potluck for the math department.
We will meet in the Amphitheater in Ashkelon National Park on Sunday, October 20th, 2019, at 11:00, take a walk and have a picnic.

A potluck is a party or a picnic where each guest brings some food to share with the others. It is recommended that every family with $N$ members brings a dish (choice of dish entirely up to you), which should be enough for at least $(N+4)$ people.

If you are interested in attending, please register here.

Here is some information about the park.

Remark: one needs to buy a ticket at the entrance to enter the park (the prices appear in the website above).

Some older events may be found on the pages of the Center for Advanced Studies.

### אירועי העבר

• 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.

• 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.

• Mathematical Midrasha in the Negev(*) Feb 19, 09:00-Feb 21, 17:00, 2019, שדה בוקר.

המדרשה היא כנס מתמטי המיועד לתלמידי מתמטיקה משנה ג‘ והלאה, והיא תכלול ארבע סדרות של הרצאות על ידי חברי סגל מהמחלקה למתמטיקה באוניברסיטת בן-גוריון בנגב. זוהי הזדמנות להכיר חוקרים פעילים במתמטיקה, לשמוע הרצאות על תחום מחקרם באווירה ידידותית, לשוחח עימם ולשאול שאלות על מחקר מתמטי.

• Lie Superalgebra Day(*) Dec 25, 2018, room -101.

Official Website (containing the full program) and Poster

• Complex and Symplectic geometry(*) May 8, 11:00-16:00, 2018, Math -101, BGU.

• Set Theory, Model Theory and Applications(*) Apr 22-26, 2018, Eilat Campus of Ben-Gurion University of the Negev (Israel).

• Cohn‘s theory of universal skew fields of fractions Feb 6, 11:30-Feb 18, 11:30, 2018, Room -101.

Jurij Volcic (BGU) will give three lectures on the theory of universal skew fields of fractions due to P.M. Cohn, a beautiful and powerful tool of noncommutative algebra little known outside of a small circle of cognoscenti. Everybody is invited (the lectures should be accessible for graduate students).

Time and place:

Tuesday Feb. 6, Thursday Feb. 15, and Sunday Feb. 18 at 11:30-13:00 in Room -101

Abstract:

As opposed to the commutative setting, localization in noncommutative rings is a much more intricate topic, accompanied with various subtle obstacles and at first sight counter-intuitive phenomena. An exceptional contribution to this field has been made by Paul Moritz Cohn (1924-2006) with the introduction of universal skew fields of fractions in the 70‘s, and his subsequent development of this theory. In the self-contained course of three talks I will try to present some of Cohn‘s core results with the view towards the universal skew field of fractions of a free algebra.

In the first lecture we will consider the general problem of embedding rings into skew fields, and early difficulties accompanying it. Following Cohn we will then introduce the category of epic skew fields and specializations assigned to a fixed ring. This will allow us to talk about universal skew fields of fractions and to draw parallels with the commutative theory.

In the second lecture we will explain the interplay between specializations, singular kernels, matrix ideals in matrix representation of fractions. Our aim will be to determine necessary and sufficient conditions for a ring to admit a (universal) skew field of fractions.

In the last lecture we will finally look at a concrete family of rings admitting universal skew fields of fractions: free ideal rings (firs), among which are free algebras, and their generalizations. We will trace down their distinguishing property that fulfills the sufficient condition from the previous lecture.

• School on Polish Groups(*) May 22-27, 2016, Midreshet Sde-Boker.

The School will focus on Polish Groups. General theory, examples, representations of discrete groups with Polish targets, and applications to discrete groups, geometry and dynamics. The three main courses will be:

### Mini-Courses###

1. General theory of Polish groups Jullien Melleray, Christian Rosendal and Todor Tsankov.
2. Algebraic groups over Polish fields. Jean Lécureux and Bertrand Rémy.
3. Infinite dimensional Lie groups and their symmetric spaces Bruno Duchesne.
• ערב חשיפה לתארים מתקדמים Apr 12, 17:00-18:30, 2016, חדר סמינרים (101-), בניין 58.

• Algebraic Combinatorics day(*) Mar 29, 2016, Room -101, Math building (58), BGU.

In honor of Prof. Mikhail Klin, on the occasion of his retirement

• Special Seminar Jun 16, 10:00-11:00, 2015, Room -101, BGU.

Speaker: Antoine Ducros (Paris 6)

Title: Stability of Gauss valuations

Abstract:

A valued field $(k,|.|)$ is said to be stable (this terminology has no link with model-theoretic stability theory) if every finite extension $L$ of $k$ is defectless, i.e., satisfies the equality $\sum e_vf_v=[L:k]$, where $v$ goes through the set of extensions of $|.|$ to $L$, and where $e_v$ and $f_v$ are the ramification and inertia indexes of $v$. The purpose of my talk is to present a new proof (which is part of current joint reflexions with E. Hrushovski and F. Loeser) of the following classical fact (Grauert, Kuhlmann, Temkin,…) : let $(k,|.|)$ be a stable valued field, and let $(r_1,\dots,r_n)$ be elements of an ordered abelian group $G$ containing $|k^*|$. Let $|.|‘$ be the $G$-valued valuation on $k(T_1,\dots,T_n)$ that sends $\sum a_I T^I$ to $\max_I |a_I|\cdot r^I$. Then $(k(T_1,\dots,T_n),|.|‘)$ is stable too.

Our general strategy is purely geometric, but the proof is based upon model-theoretic tools coming from model theory (which I will first present; no knowledge of model theory will be assumed). In particular, it uses in a crucial way a geometric object defined in model-theoretic terms that Hrushovski and Loeser attach to a given $k$-variety $X$, which is called its stable completion; the only case we will have to consider is that of a curve, in which the stable completion has a very nice model-theoretic property, namely the definability, which makes it very easy to work with.

• Operator algebras and operator theory May 13, 11:10-15:30, 2015, BGU.

Joint Operator Algebras and Operator Theory Seminar, bringing together people from Ben-Gurion University, the Technion, Tel Aviv University and the University of Haifa

• Award of the Noriko Sakurai Postdoctoral Fellowship(*) May 12, 2015, BGU.

• Distinguished Lecture Series: Prof. Ilijas Farah, York University, Canada May 7-18, 2015, BGU.

• Ergodic Theorems and Applications in Probability(*) May 3-8, 2015, Eilat.

• Action NOW(*) Mar 24, 2015, BGU.

• The Moshe Flato Lecture Series 2015 Mar 12, 2015, BGU.

• Workshop on Generalized Cohomology(*) Feb 8-12, 2015, Sde Boker.

• TRATC2014 - Tropicalization, Realization, and Algebraic-Tropical Correspondence(*) Sep 28-Oct 3, 2014, Eilat.

• Award of the Noriko Sakurai Postdoctoral Fellowship(*) May 20, 2014, BGU.

• 30th European Workshop on Computational Geometry (EuroCG 2014)(*) Mar 3-5, 2014, Ein Gedi.

• Workshop on the Central Limit Theorem(*) Jul 2, 2013, Ben-Gurion University, math. dept. building.

• Interactions between Logic, Topological structures and Banach spaces theory(*) May 19-24, 2013, Eilat.

• Action Now Seminar: Mostow and Rigidity(*) May 7, 2013, Ben-Gurion University Math dept. building.

• Workshop on Algebraic, Analytic, and Tropical Geometry (AATG2013)(*) Apr 28-May 3, 2013, Kibbutz Ein Gedi.

• Mini conference in operator algebras(*) Apr 9-10, 2013, BGU.

• Spring School on Group C*-algebras(*) Mar 17-21, 2013, Sde Boker.

• Workshop on C*-algebras and Noncommutative Dynamics(*) Mar 11-14, 2013, Sde Boker.

• Dynamics on parameter spaces 2013 Jan 27-Feb 1, 2013, Sde Boker.

• Award of the Noriko Sakurai Postdoctoral Fellowship for 2013(*) Dec 25, 2012, BGU.

• The Moshe Flato Lecture Series 2011 Mar 10, 2011, BGU.

• The Moshe Flato Lecture Series 2008 Nov 27, 2008, BGU.

• The Moshe Flato Lecture Series 2007 Mar 20, 2007, BGU.

• The Moshe Flato Lecture Series 2004 Nov 25, 2004, BGU.

• The Moshe Flato Lecture Series 2002 Nov 28, 2002, BGU.

(Star) מסמל אירועים הנתמכים בחלקם על-ידי המרכז ללימודים מתקדמים במתמטיקה באוניברסיטת בן-גוריון