Seminars

2018 Nov 27

T&G: Graham Denham (Western University), Cohomological vanishing and abelian duality

2:00pm to 3:30pm

Location: 

Room 209, Manchester Building, Jerusalem
Cohomology jump loci are secondary cohomological invariants of discrete groups and topological spaces. I will describe some recent work on the cohomology jump loci of complements of unions of smooth complex hypersurfaces, and I will motivate the notion of abelian duality spaces that I introduced in joint work with Alex Suciu and Sergey Yuzvinsky. The study of such hypersurface arrangements involves a mix of combinatorics and complex geometry.
2018 Nov 27

Yan Dolinsky. A new type of stochastic target problems.

12:00pm to 1:00pm

Location: 

Coffee lounge
Abstract: I will discuss two stochastic target problem in the Brownian framework . The first problem has a nice solution which I will present. The second problem is much more complicated and for now remains open. I will discuss the challenges and connection with other fields in probability theory.
2018 Dec 12

Set Theory Seminar: Yair Hayut "Chang's Conjecture" (Part III)

2:00pm to 3:30pm

Location: 

Ross 63
Title: Chang's Conjecture (joint with Monroe Eskew) Abstract: I will review some consistency results related to Chang's Conjecture (CC). First I will discuss some classical results of deriving instances of CC from huge cardinals and the new results for getting instances of CC from supercompact cardinals, and present some open problems. Then, I will review the consistency proof of some versions of the Global Chang's Conjecture - which is the consistency of the occurrence many instances of CC simultaneously. We will aim to show the consistency of the statement: (\mu^+,\mu) -->> ( u^+,
2018 Nov 28

Set Theory Seminar: Yair Hayut "Chang's Conjecture" (Part II)

2:00pm to 3:30pm

Location: 

ross 63
Title: Chang's Conjecture (joint with Monroe Eskew) Abstract: I will review some consistency results related to Chang's Conjecture (CC). First I will discuss some classical results of deriving instances of CC from huge cardinals and the new results for getting instances of CC from supercompact cardinals, and present some open problems. Then, I will review the consistency proof of some versions of the Global Chang's Conjecture - which is the consistency of the occurrence many instances of CC simultaneously. We will aim to show the consistency of the statement: (\mu^+,\mu) -->> ( u^+,
2018 Nov 26

Combinatorics: Ron Adin, BIU, "Cyclic permutations, shuffles and quasi-symmetric functions"

11:00am to 1:00pm

Location: 

Rothberg CS bldg, room B500, Safra campus, Gival Ram
Speaker: Ron Adin, Bar-Ilan University Title: Cyclic permutations, shuffles and quasi-symmetric functions Abstract: By a theorem of Stanley, the distribution of descent number over all the shuffles of two permutations depends only on the descent numbers of these permutations. For a quantitative version of this result and its cyclic analogue, we use a new cyclic counterpart of Gessel's ring of quasi-symmetric functions, together with an unusual homomorphism and a mysterious binomial identity. No previous acquaintance assumed.
2018 Nov 21

Logic Seminar - Saharon Shelah

11:00am to 1:00pm

Location: 

Ross 63
קשת איוּם מוֹדל כוֹלל

the spectrum of the existence of a universal model


תמצית/abstract:
קיוּם מוֹדל כולל של תורה בעצמה נתוּנה זו שאלה טבעית בתוֹרת המוֹדלים ובתוֹרת הקבוּצוֹת. נטפל בתנאים מספיקים לאי קיוּם, אין צוֹרך בידיעוֹת מוּקדמוֹת.

The existence of a universal model (of a theory T in a cardinal lambda)  is a natural question in model theory and set theory.  We shall deal with new sufficient conditions for non-existence.
No need of previous knowledge
2018 Dec 26

Logic Seminar - Antongiulio Fornasiero

11:00am to 1:00pm

Location: 

Ross 63

Generic derivations on o-minimal structures
Antongiulio Fornasiero

A derivation on a field K is a map d from K to K such that  d(x + y) = d(x) + d(y) and d(x y) = x d(y) + d(x) y.

Given an o-minimal structure M in a language L, we introduce the notion L-derivation, i.e derivation compatible with L. For example, if M is the field of reals with exponentiation, then we further require that the derivation d satisfies d(exp x) = exp(x) d(x).

2018 Nov 20

T&G: Gangotryi Sorcar (Hebrew University), On the topology of the Teichmuller space of negatively curved Riemannian metrics

2:00pm to 3:30pm

Location: 

Room 209, Manchester Building, Jerusalem
This talk is a survey on results concerning the Teichmuller space of negatively curved Riemannian metrics on M. It is defined as the quotient space of the space of all negatively curved Riemannian metrics on M modulo the space of all isotopies of M that are homotopic to the identity. This space was shown to have highly non-trivial homotopy when M is real hyperbolic by Tom Farrell and Pedro Ontaneda in 2009.

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