2017 May 03

# סמינר תלמידי מחקר - אריאל רפפורט

12:00pm to 1:00pm

## Location:

רוס 70A
Title: Bernoulli convolutions and Erdős's argument for singularity
2018 Jan 24

# סמינר תלמידי מחקר - יתיר הלוי

10:00am to 11:00am

2016 Nov 07

# סמינר תלמידי מחקר - יתיר הלוי

11:45am to 1:00pm

## Location:

70A
מרצה: יתיר הלוי כותרת: למה ל-{e^{-x^2 אין פונקציה קדומה אלמנטרית? תקציר: במהלך התואר הראשון מבקשים מאתנו להאמין בכל מיני אמיתות מתמטיות (לא כולן קשות) אך לא תמיד מספקים לנו הוכחה. בין השאר, הבנייה של המספרים הממשיים באינפי 1, אי קיום פונקציה קדומה לפונקציות מסוימות ותורת הקבוצות הנאיבית. נוכיח, עד כדי כמה פרטים טכנים, את אי-הקיום של פונקציה קדומה אלמנטרית ל-{e^{-x^2, הדגש יהיה על ההגדרות והניסוח הנכון לשאלה. נשתמש ברעיונות אלה כדי לתת הקדמה לתורת גלואה הדיפרנציאלית, מה היא יכולה להגיד על פתרונות למשוואות דיפרנציאליות ואיך כל זה קשור לכותרת ההרצאה.
2018 Dec 18

# Matthew Foreman (UC IRVINE), Global Structure Theorems for the space of measure preserving transformations

2:15pm to 3:15pm

Abstract: This talk describes two classes of symbolic topological systems, the odometer based and the circular systems. The odometer based systems are ubiquitous--when equipped with invariant measures they form an upwards closed cone in the space of ergodic transformations (in the pre-ordering induced by factor maps). The circular systems are a small class, but represent the diffeomorphisms of the 2-torus built using the Anosov-Katok technique of approximation by conjugacy.

2018 Nov 27

# Amir Dembo (Stanford), Large deviations of subgraph counts for sparse random graphs

2:15pm to 3:15pm

## Location:

Ross 70
For fixed t>1 and L>3 we establish sharp asymptotic formula for the log-probability that the number of cycles of length L in the Erdos - Renyi random graph G(N,p) exceeds its expectation by a factor t, assuming only that p >> log N/sqrt(N). In a narrower range of p=p(N) we obtain such sharp upper tail for general subgraph counts and for the Schatten norms of the corresponding adjacency matrices. In this talk, based on a joint work with Nick Cook, I will explain our approach, based on convex-covering and a new quantitative refinement of
2018 Dec 11

# Demi Allen (Manchester) A mass transference principle for systems of linear forms with applications to Diophantine approximation

2:15pm to 3:15pm

## Location:

Ross 70
Abstract: In Diophantine approximation we are often interested in the Lebesgue and Hausdorff measures of certain $\limsup$ sets. In 2006, Beresnevich and Velani proved a remarkable result --- the Mass Transference Principle --- which allows for the transference of Lebesgue measure theoretic statements to Hausdorff measure theoretic statements for $\limsup$ sets arising from sequences of balls in $\mathbb{R}^k$.
2018 Nov 14

# Set Theory Seminar: Shimon Garti "On the consistency of d_lambda > r_lambda for a singular cardinal lambda"

2:00pm to 3:30pm

## Location:

Ross 63
Abstract: We shall try to prove the consistency of d_lambda > r_lambda (and even d_lambda > u_lambda) for a singular cardinal lambda. This is a joint work with Saharon.
2018 Nov 05

# NT&AG: Michael Temkin (HUJI), ""Differential forms on Berkovich curves"

3:00pm to 4:00pm

## Location:

Room 70A, Ross Building, Jerusalem, Israel
This is a continuation of the talk on October 29. After finishing a brief review of basic facts about Berkovich curves, I will associate a reduction datum to differential forms on such curves and explain how a lifting theorem for such data is proved and why it reproves the lifting theorem of [BCGGM].
2018 Oct 31

# Logic Seminar - Yatir Halevi

11:00am to 1:00pm

## Location:

Ross 63

Around the stable and dependent fields conjecture

Abstract: The stable fields conjecture asserts that every infinite stable field is separably closed.
We will talk a bit about the history of this conjecture, its connection to an analogous conjecture on dependent fields and some of their consequences.
Finally, we will end by proving the conjecture for fields of finite dp-rank.
2019 Jan 14

# Combinatorics: Frank Mousset, TAU, "The upper tail for triangles in sparse random graphs"

11:00am to 1:00pm

## Location:

Rothberg CS bldg, room B500, Safra campus, Givat Ram
Speaker: Frank Mousset, TAU Title: The upper tail for triangles in sparse random graphs Abstract:
2018 Dec 19

# Set Theory Seminar - Asaf Karagila (The Morris model)

2:00pm to 3:30pm

## Location:

Ross 63
Title: The Morris model Abstract: Douglass Morris was a student of Keisler, and in 1970 he announced the following result: It is consistent with ZF that for every \alpha, there is a set A_\alpha which is the countable union of countable sets, and the power set of A_\alpha can be partitioned into \aleph_\alpha non-empty sets. The result was never published, and survived only in the form of a short announcement and an exercise in Jech's "The Axiom of Choice". We go over the proof of this theorem using modern tools, as well as some of its odd implications about "size" and countability.
2018 Oct 31

2:00pm to 3:29pm

2018 Oct 29

# NT&AG: Michael Temkin (HUJI), ""Differential forms on Berkovich curves"

2:30pm to 3:30pm

## Location:

Room 70A, Ross Building, Jerusalem, Israel
The moduli space of smooth curves with a chosen differential form has a natural stratification by the pattern of zeros of the form. In a recent paper of Bainbridge-Chen-Gendron-Grushevsky-Moeller, one used a complicated complex-analytic technique to explicitly describe a compactification of these strata. In a joint work in progress with I. Tyomkin we provide an algebraic proof of these results based on studying differential forms on Berkovich curves over fields of residual characteristic zero.
2018 Oct 24

# Set Theory Seminar (Ross 63)

2:00pm to 3:30pm

## Location:

Ross 63
לאירוע הזה יש שיחת וידאו. הצטרף: https://meet.google.com/bbc-knox-fds +1 225-434-0384 קוד גישה: 826117698#
2018 Dec 18

# Dynamics Lunch: Omer Ben-Neria "Dichotomies for Borel equivalence relations"

12:00pm to 1:00pm

Abstract: We would like present several results in descriptive set theory involving definable equivalence relations on Polish spaces. Given an equivalence relation E on a polish space X, we would like to study the classification problem of determining whether two objects x,y in X are E-related.