Algebra and Number Theory Seminars - 2017

Date Speaker and Affiliation Title of the Talk (Click on title to view abstract)
07-11-2017 Sudeshna Roy

Gotzmann's regularity and persistence theorem – III

Gotzmann's regularity theorem establishes a bound on Castelnuovo-Mumford regularity using a binomial representation (the Macaulay representation) of the Hilbert polynomial of a standard graded algebra. Gotzmann's persistence theorem shows that once the Hilbert function of a homogeneous ideal achieves minimal growth then it grows minimally for ever. We start with a proof of Eisenbud-Goto's theorem to establish regularity in terms of graded Betti numbers. Then we discuss Gotzmann's theorems in the language of commutative algebra.

03-11-2017 Saurav Bhaumik

Higgs bundles

We will describe the general fiber of the Hitchin fibration for the classical groups.

31-10-2017 Provanjan Mallick

Asymptotic prime divisors – III

Consider a Noetherian ring R and an ideal I of R. Ratliff asked a question that what happens to Ass(R/I^n) as n gets large ? He was able to answer that question for the integral closure of I. Meanwhile Brodmann answered the original question, and proved that the set Ass(R/I^n) stabilizes for large n. We will discuss the proof of stability of Ass(R/I^n). We will also give an example to show that the sequence is not monotone. The aim of this series of talks to present the first chapter of S. McAdam, Asymptotic prime divisors, Lecture Notes in Mathematics 1023, Springer-Verlag, Berlin, 1983.

31-10-2017 Sudeshna Roy

Gotzmann's regularity and persistence theorem - II

Gotzmann's regularity theorem establishes a bound on Castelnuovo-Mumford regularity using a binomial representation (the Macaulay representation) of the Hilbert polynomial of a standard graded algebra. Gotzmann's persistence theorem shows that once the Hilbert function of a homogeneous ideal achieves minimal growth then it grows minimally for ever. We start with a proof of Eisenbud-Goto's theorem to establish regularity in terms of graded Betti numbers. Then we discuss Gotzmann's theorems in the language of commutative algebra.

27-10-2017 Sudarshan Gurjar and Saurav Bhaumik

Higgs Bundles

We will define the moduli of Higgs bundles and the Hitchin fibration, which is a morphism from the moduli of Higgs bundles to an affine space. Then we will describe the general fibre in terms of the spectral cover.

25-10-2017 Santosh Nadimpalli

Typical representations for depth-zero representations.

We are interested in understanding cuspidal support of smooth representations of p-adic reductive group via understanding the restriction of a smooth representation to a maximal compact subgroup. This is motivated by arithmetic applications via local Langlands correspondence. We will explain the case of general linear groups and classical groups.

24-10-2017 Provanjan Mallick

Asymptotic prime divisors – II

Consider a Noetherian ring R and an ideal I of R. Ratliff asked a question that what happens to Ass(R/I^n) as n gets large ? He was able to answer that question for the integral closure of I. Meanwhile Brodmann answered the original question, and proved that the set Ass(R/I^n) stabilizes for large n. We will discuss the proof of stability of Ass(R/I^n). We will also give an example to show that the sequence is not monotone. The aim of this series of talks to present the first chapter of S. McAdam, Asymptotic prime divisors, Lecture Notes in Mathematics 1023, Springer-Verlag, Berlin, 1983.

24-10-2017 Sudeshna Roy

Gotzmann's regularity and persistence theorem

Gotzmann's regularity theorem establishes a bound on Castelnuovo-Mumford regularity using a binomial representation (the Macaulay representation) of the Hilbert polynomial of a standard graded algebra. Gotzmann's persistence theorem shows that once the Hilbert function of a homogeneous ideal achieves minimal growth then it grows minimally for ever. We start with a proof of Eisenbud-Goto's theorem to establish regularity in terms of graded Betti numbers. Then we discuss Gotzmann's theorems in the language of commutative algebra.

20-10-2017 Sudarshan Gurjar and Saurav Bhaumik

Higgs Bundles

In this second talk of the series, I will continue the discussion on Higgs bundles with focus on some of the moduli aspects of the theory.

17-10-2017 Provanjan Mallick

Asymptotic prime divisors.

Consider a Noetherian ring R and an ideal I of R. Ratliff asked a question that what happens to Ass(R/I^n) as n gets large ? He was able to answer that question for the integral closure of I. Meanwhile Brodmann answered the original question, and proved that the set Ass(R/I^n) stabilizes for large n. We will discuss the proof of stability of Ass(R/I^n). We will also give an example to show that the sequence is not monotone. The aim of this series of talk to present the first chapter of S. McAdam, Asymptotic prime divisors, Lecture Notes in Mathematics 1023, Springer-Verlag, Berlin, 1983.

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