Algebra and Number Theory Seminars - 2017

Date Speaker and Affiliation Title of the Talk (Click on title to view abstract)
03-03-2017 Sudarshan Gurjar

Borel-Weil-Bott theorem

In this talk we shall summarize results on the structure and representation theory of semisimple algebraic groups. This will to prepare ground for the subsequent talks on the Borel-Weil-Bott theorem which explains how (loosely speaking) representations of semisimple algebraic groups can be obtained as sheaf cohomology groups associated to certain line bundles.

03-03-2017 Dr. V. Mukundan, TIFR

Title: Ideals of Linear type-3

In this talk, we study the basics of defining ideal of the Rees algebra of Ideal I and what makes the ideal to be of linear type. Further, we prove that ideals generated by a regular sequences are of linear type.

28-02-2017 Dr. Shreedevi Masuti, University of Genoa

Symbolic Rees Agebra of certain monomial curves

24-02-2017 J. K. Verma

Counting Zeros of Multivariate Laurent Polynomials and Mixed Volumes of Polytopes

A result of D.N. Bernstein proved in the late seventies gives an upper bound on the number of common solutions of n multivariate Laurent polynomials in n indeterminates in terms of the mixed volumes of their Newton polytopes. This bound refines the classical Bezout's bound. Bernstein's Theorem has several proofs using techniques from numerical analysis, intersection theory and tori varieties. B. Teissier proved the theorem using intersection theory. A proof using theory of toric varieties can be found in the book by W. Fulton on the same subject. In this talk, I will outline an algebraic proof similar to the standard proof of Bezout's Theorem. This proof, found in collaboration with N.V. Trung, uses basic results about Hilbert functions of multigraded algebras first proved by van der Waerden.

20-02-2017 Ronnie Sebastian

Deligne's conjectures on critical values of L-functions

We will explain how to attach an L-function to a motive, what the critical points of this L-function are, and Deligne's conjectures on the values of the L-function at critical points.

17-02-2017 Dr. Vivek Mukundan

Ideals of linear type 2

In this talk, we study the basics of defining ideal of the Rees algebra of Ideal I and what makes the ideal to be of linear type. Further, we prove that ideals generated by a regular sequences are of linear type.

15-02-2017 Eshita Mazumdar, IIT Bombay

An Extremal Problem in the study of Zero-Sum Problems

For a finite abelian group G with |G|= n, the arithmetical invariant EA(G) is defined to be the least integer k such that any sequence S with length k of elements in G has a A weighted zero-sum subsequence of length n. When A={1}, it is the Erdos-Ginzburg-Ziv constant and is denoted by E(G). Similarly, the Davenport Constant DA(G) is defined to be the least integer k such that any sequence S with length k of elements in G has a non-empty A weighted zero-sum subsequence. For certain sets A, we already know some general bounds for these weighted constants corresponding to the cyclic group Z_n. We try to find out bounds for these combinatorial invariants for random A. We got few results in this connection. In this talk I would like to present those results and discuss about an extremal problem related to the cardinality of A

10-02-2017 Dr. Vivek Mukundan

Ideals of Linear Type I

In this talk, we study the basics of defining ideal of the Rees algebra of Ideal I and what makes the ideal to be of linear type. Further, we prove that ideals generated by a regular sequences are of linear type.

09-02-2017 Saurav Bhaumik

Some consequences of the Riemann hypothesis for varieties over finite fields - II

We will talk about a result of M. Katz and W. Messing, which says the following. From the Riemann hypothesis and the hard Lefschetz theorem in l-adic cohomology, the corresponding facts for any Weil cohomology follow.

08-02-2017 R. V. Gurjar

Rational Singularities VI

We will prove a purely numerical criterion due to M. Artin to test the rationality of a surface singularity. In practice this is the criterion which is used when a rational surface singularity is being considered.

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