Mathematics Seminar at IISER, Pune 2009-10



IISER, Pune Anupam Singh


The seminar will take place in the lecture room W302 (on the 3rd floor of west wing).

Date and Time Speaker Title Abstract
17 April 2010, 11AM Supriya Pisolkar, TIFR Mumbai Local Fields We will begin with the definition of discrete valued fields. Local fields are special examples of such fields. After discussing important properties like Hensel's lemma, we will study types of extensions of local fields. If time permits we will also see the the statement of local class field theory.
16 April 2010, 3PM Amit Hogadi, TIFR Mumbai The Brauer group of a field. This talk will start with definition of central simple algebras and some elementary properties of Brauer group of a field. Towards the end we will see some interesting problems and conjectures which are still open.
07-09 April 2010, 3PM Prof. Akhil Ranjan, IIT Bombay Differential Geometry of Curves and Surfaces in R3 Abstract
05 April 2010, 11AM A. Chandrashekaran Linear and semidefinite linear complementarity problems. In this talk we will see a brief introduction to the linear complementarity problems (LCP) and the semidefinite linear complementarity problems(SDLCP). We begin with the definition of (LCP) and illustrate it with some examples. Then we move to the SDLCP's. Here we give some examples of SDLCP's and we show how SDLCP's includes LCP as its special case. We also discuss the difficulties that we will face when working with SDLCP's compared to LCP's. Finally we will see few results from my earlier research work.
24 March 2010, 3PM Nageswara Rao Simulations for modelling population balance equations of particulate process using discrete particle model. Not received yet
22,23 March 2010, 3PM Rama Mishra Galois Theory for Differential Equations. Abstract
15, 16 March 2010, 3PM Vivek Mallick Projective Spaces, Grassmannians and Gaussian binomials. In this talk we define grassmannians over a finite fields. We go on to find out the cardinality of these finite sets. We show that the cardinality have properties similar to those of binomial coefficients.
09 March 2010, 3PM Sreekar Vadlamani, Technion, Israel Wiener space and the geometry of random fields This talk is broadly divided into two parts: In the first part, we shall study some geometric aspects of the Wiener space. In particular, we shall extend the well known (for the old-school Statisticians, and the old-German-school Geometers) "Tube formula", to the case of infinite dimensions, using the infinite dimensional calculus set forth by L. Gross and P. Malliavin. Then, in the second part, we shall use the results obtained in the first part, to understand the geometry of random fields defined on smooth manifolds.
05 March 2010, 12 Noon Sankaran Viswanath, IISc Bangalore Constant Term Identities In his 1962 study of the statistical theory of energy levels of complex nuclei, Freeman Dyson was led to conjecture an identity for the associated Boltzmann partition function in closed form. Over the next 3 decades, this "constant term identity" has been progressively generalized and its connections to Lie algebras and associated structures unearthed. I will narrate parts of this story, including a recently discovered relation to polynomial analogs of weight multiplicities in representations of affine Lie algebras.
25 February 2010 , 2PM Rabeya Basu, IISER Kolkata A Problem of J.P.-Serre on Projective Modules In 1956, J.P.-Serre posed a problem on projective modules. During 60's many Indian mathematicians of Tata Institute were motivated by this problem and showed their profound contributions. In 1958, C.S. Seshadri gave a proof for a special case. It took 20 years to get the general solution of the problem. Finally, it was proved by Daniel Quillen and Andrei Suslin Independently in 1976. Now it is known as Quillen-Suslin Theorem. In this talk I will discuss few problems related to the above famous result.
23 February 2010, 3 PM Aparajita Dasgupta, IISc Bangalore The Twisted Laplacian, the Laplacians on the Heisenberg Group and SG Pseudo-Differential Operators Abstract
19 February 2010, 3PM Amit Bose Two case studies on what controls a neuron's firing properties Neurons convey signals throughout the nervous system by firing action potentials which are large voltage deviations from a resting state. In many cases, a neuron needs to receive input from other neurons in order to produce an action potential. In this talk, I will discuss two examples of this situation. The first involves coincidence detection where a neuron must calculate the time difference between distinct inputs and display a firing rate that is inversely related to this difference. This problem is related to how animals localize sound sources. The second example involves sustained activity in a working memory model. In this situation, a neuron is recruited into an ongoing activity pattern if and only if it receives a number of sufficiently strong inputs in a short enough window of time. Mathematical models for both phenomena will be presented. The analysis of these models relies on tools from non-linear dynamical systems.
18 February 2010, 3PM S. K. Sahoo, IIT Madras, Chennai Quasihyperbolic Distance and Quasiconformal Mappings

Notes of the talk
Quasihyperbolic distance is a generalization of the hyperbolic distance, in the sense that they are equal in the upper half plane of the complex plane. We study the quasihyperbolic distance on arbitrary proper subdomains of the real Euclidean spaces with dimension at least two. We consider certain geometric properties of arc lengths and characterize domains (open and connected sets) in terms of the quasihyperbolic distance where the geometric properties hold. In the sequel, we investigate invariance properties of such domains under quasiconformal mappings.
6, 7 February 2010, 10AM - 5PM Professor Rajeev Karandikar, Cranes Software International Ltd, Bangalore Introduction to Statistics (from the organiser) These will be Marathon interactive discussion sessions to introduce statistics to the undergraduate students. The aim will be to see how one can apply simple statistical ideas to solve many problems.
3 February 2010, 3 PM Krishnendu Gongopadhyay, ISI Kolkata On the Existence of an Invariant Non-degenerate Bilinear Form under a Linear Map. Let $V$ be a vector space over a field $F$ of characteristic different from $2$. Let $T: V --> V$ be an invertible linear map. We shall discuss an answer to the following question in this talk: When does $V$ admit a $T$-invariant non-degenerate symmetric (resp. skew-symmetric) bilinear form? Along the way we shall apply our result to give a characterization of the real elements in the general linear group $GL(n, F)$.
2 February 2010 3PM Saikat Chatterjee, S.N. Bose National Centre for Basic sciences Parallel transport on the path space and category theory A p-form on path space PM can be constructed from a p-form and a p+1-form on the space M. Similarly from a Lie algebra valued 1-form A and a Lie algebra valued 2-form B on Principal fiber bundle one can construct a connection on path space bundle. But a single group is not sufficient for non Abelian description of surface holonomy ("No go" theorem)! Introducing another group one can define a 'consistent' surface holonomy for the non Abelian case. This introduction of a second group leads to an interesting categorical picture of the surface holonomy. As in pathspace a 'point'is basicaly a 'path' in base space, path space formalism can be very useful to study dynamics of an extended object like string.
3 February 2010, 5PM Vijay Patankar, Microsoft Research, Bangalore Factoring polynomials and Abelian Varieties An irreducible polynomial with integer coefficients can factor modulo p for every prime p. We study a geometric analogue of this phenomenon in the context of Abelian varieties.
27, 28 January 2010, 3PM Rama Mishra, IISER Pune Topological Quantum Field Theory (TQFT) A topological quantum field theory (TQFT) is an, almost, metric independent quantum field theory that gives rise to topological invariants of the background manifold. This is a nice interplay between Topology and Algebra. We will see that in dimension 2, the category of 2d TQFTs are in one to one correspondence with the category of Commutative Frobenius Algebras.
20, 21 January 2010, 3PM Anupam Kumar Singh, IISER Pune Orthogonal and Symplectic Groups We will define Orthogonal and Symplectic groups and study some of it's properties.
12 January 10, 3PM Prof. S. M. Bhatwadekar, TIFR Mumbai Completion of Unimodular Rows over Integers Abstract
08 January 10, 3PM Professor Mahesh Nerurkar, Rutgers University on Lyapunov Exponents Not recieved Yet
10 December 09, 3PM Abhijit pal Trees of Spaces and Cannon-Thurston Maps. In this talk, we will first introduce trees of strongly relatively hyperbolic spaces and then we will prove that if X is a tree of relatively hyperbolic spaces satisfying some conditions, then, for a vertex spaces Y, a Cannon-Thurston map exists for the embedding i:Y -> X, i.e., i can be extended continuously to their boundaries. Using same technique, for the above short exact sequence of relatively hyperbolic groups, we can prove that a Cannon-Thurston map for the inclusion i:K -> G exists.
09 December 09, 1PM Abhijit pal Relative Hyperbolicity and Quasi-Isometric section. In this talk, we will introduce hyperbolic and strongly relatively hyperbolic spaces (groups). We will give two definitions of a relatively hyperbolic space (due to Gromov and Farb). We will define nearest point projections and discuss several properties of it. For a short exact sequence of finitely generated groups 1 -> K -> G -> Q -> 1, we will prove that if K is relatively hyperbolic and G preserves cusp subgroups of K, then there exists a quasi-isometric section from Q to G.
23 November 2009, 4PM Prof. Rajeeva Karandikar, Cranes Software Bangalore Opinion polls, Exit polls and Early seat projections How can talking to a few thousand people enable one to predict the mood of the Nation? This is the question I will focus on and talk about opinion polls, exit polls in Indian context. I will share my experiences over the last 10 years. No specific background in Statistics or Mathematics is assumed (other than Class 12 Maths).   Notes
11-13 November 2009, 11 AM - 12 Noon Prof. N. Raja, TIFR, Mumbai An Introduction to the Axiomatic Method Yet to recieve
28 October 2009, 11 AM - 1PM Prof. Gautam Bharali, IISc Bangalore Analytic Continuation in Several Complex Variables Notes
26 October 2009, 3 PM Prof. Gautam Bharali, IISc Bangalore Analytic Continuation in Several Complex Variables The theory of functions in several complex variables is challenging because of several unexpected phenomena that have no analogues in one variable. One such phenomenon is that there exists domains in C^n, n>1, for which EVERY holomorphic function defined on this domain analytically continues past the boundary. Demonstrating this is quite easy, and requires nothing more than an understanding of Cauchy's integral formula and Laurent series. In the first lecture, we shall recapitulate some of the one-variable results that shall be exploited later -- and this lecture will be accessible to all students who have seen some complex analysis. The second lecture will be devoted to the phenomenon mentioned above, and will be based on entirely elementary tools. The third lecture will be concentrate on some new results on the theme of analytic continuation.
21 October 2009, 3 PM Prof. G. Misra, IISc Bangalore Invariants for linear transformations We show how to extract unitary invariants for a linear transformation from the unitary invariants for its restrictions to a family of (finite dimensional) subspaces. Often it is possible to (holomorphically) glue these subspaces and produce a holomorphic Hermitian vector bundle. Then one sees that the invariants for the restriction operators and the invariants for the holomorphic Hermitian vector bundle determine each other.
20 October 2009 Prof. Amit Kulshrestha, IISER Mohali Group Theory and Puzzles Notes
06 October 2009, 3 PM Prof. Siddhartha Gadgil, IISc Bangalore Coarse geometry and Curvature : A glimpse into the work of Mikhail Gromov. Coarse Geometry is the study of geometry `seen from far away'. We will explain what coarse geometry is as well as classical and coarse notions of curvature. We also discuss related geometric notions of approximating by finite sets and taking limits of metric spaces. This lecture will be informal and accessible. Only a basic knowledge of Calculus is assumed (even that in only part of the talk).
21 September 2009, 4 PM Prof. K. Srinivas, IMSc, Chennai Summation of Arithmetical Fuctions Given a counting function $f$, one would like to know how to estimate $ \sum_{n\leq x} f(n)$. For example, if $ f(n)=1$ when $n$ is prime, and $0$, otherwise, then one is asking how many primes are there upto $x$. We shall discuss this problem.
14 September 2009, 4 PM Dr. Shanta Laishram, Universit of Waterloo, Canada Irreducibility of generalized Schur Polynomials Abstract
17 July 2009, 3:30 PM Dr. Rama Mishra Introduction to Knot Theory We will introduce Knot invariants.
10 July 2009, 3 PM Dr. Rama Mishra Introduction to Knot Theory We will continue the introductory lecture on Knot Theory.
01 July 2009, 3 PM Dr. Rama Mishra Introduction to Knot Theory We will continue the introductory lecture on Knot Theory.
26 June 2009, 3 PM Dr. Rama Mishra Introduction to Knot Theory We will introduce Knots in the first lecture.


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