Past Seminars - 2017

Date Speaker and Affiliation Title of the Talk (Click on title to view abstract) Subject Classification
23-02-2017 S.G. Dani

Values of binary quadratic forms on integer pairs

This will be a continuation of the overview from the last week. Some details will be briefly recalled from the last time, for continuity and the benefit of new audience if any.

Geometry and Topology
22-02-2017 Kathleen Shannon, Salisbury University.

Pascal's Triangle, Cellular Automata and Serendipity: A Mathematical Tale

The talk will outline the development of the PascGalois Project. Its origins are in an exercise using Pascal's Triangle and modular arithmetic. Colors are assigned to the numbers 0, 1, ..., n-1, and Pascal's Triangle modulo n is drawn. The patterns in the triangle are then related to the properties of the cyclic group Zn. The process of drawing the triangles is then generalized to non-cyclic and non-abelian groups and the new patterns are examined in light of the properties of these groups. The images can help develop visual and intuitive understanding of concepts such as subgroup closure and quotient groups. They can also be used to discuss the relationship between mathematical properties and visual aesthetics. Finally we view Pascal's Triangle as a one-dimensional cellular automata and generalize to more general initial conditions and two dimensional automata. Many of the investigations in this project have been undertaken with students in undergraduate research projects and one outgrowth of the project has been the development of a set of visualization exercises to supplement the standard undergraduate course in abstract algebra. The web site for the project is at www.pascgalois.org.

Colloquium
22-02-2017 M S Raghunathan

h-Cobordism Thorem

Geometry and Topology
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.

Algebra and Number Theory
17-02-2017 Prof. A. R Shastri

Groups of Homotopy spheres

In a land-mark paper in 1956, J. Milnor showed that there are non standard differential structures on the 7-dimensional sphere. Six years later along with Kervaire, he introduced an abelian group structure on the set of equivalence classes of smooth structures on spheres of all dimension and determined these groups in several cases. We shall present some of the salient features of this work.

Geometry and Topology
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.

Algebra and Number Theory
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

Algebra and Number Theory
14-02-2017 Dr. Avinash Dharmadhikari, Quality Systems and Reliability, Engineering Research Centre, Tata Motors, Pune

Prediction of a Warranty Cost For a Two Dimensional Policy

In current automotive market, reliability and durability are important hygiene factors to the customer and customer’s perception about these parameters is established through length of product warranty period. Therefore, to be competitive in market, all companies aim to provide optimal warranty on their product. To decide optimal warranty period for a product, forecasting of cost to the companies due to particular warranty policy is essential. Automotive product warranty has two dimensions, time and mileage (t,m). Hence, to forecast warranty cost one has to model a bivariate distribution for (t,m) and project expected number of warranty returns within specified period (t,m). In this paper we bypass the bivariate distribution by using usage distribution and use multiple renewal processes induced by Weibull distributions to arrive at cost structure under various warranty policies.

Statistics and Probability
14-02-2017 Prof. Bikas Sinha, ISI Kolkata

Mixture Designs - a Review

We introduce standard mixture models and standard mixture designs as are well-known in the literature. Some of the less known models are also introduced briefly. Next we mention about known applications of mixture experiments in agriculture, food processing and pharmaceutical studies. Then we describe the framework of exact and approximate [or, continuous] mixture designs. A broad class of research problems posed and discussed in the published literature is presented with appropriate references.

Statistics and Probability
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.

Algebra and Number Theory
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