Title: Local root numbers for Heisenberg representations
Abstract: On the Langlands program, explicit computation of the local root numbers (or epsilon factors) for Galois representations is an integral part. But for arbitrary Galois representation of higher dimension, we do not have explicit formula for local root numbers. In our recent work (joint with Ernst-Wilhelm Zink) we consider Heisenberg representation (i.e., it represents commutators by scalar matrices) of the Weil
Title: Irreducibility of Galois representations associated to low weight Siegel modular forms
Abstract: If f is a cuspidal modular eigenform of weight k>1, Ribet proved that its associated p-adic Galois representation is irreducible for all primes. More generally, it is conjectured that the p-adic Galois representations associated to cuspidal automorphic representations of GL(n) should always be irreducible.
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.
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.
Abstract: In this talk I will show that for finite entropy countable Markov shifts the entropy map is upper semi-continuous when restricted to the set of ergodic measures. This is joint work with Mike Todd and Anibal Velozo.
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.
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.
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.
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
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).
