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Mathematics Colloquium | Amritanshu Prasad

September 14 @ 4:30 pm - 5:30 pm

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Event Details

Title: Generating Functions Associated to Species of Structures


Abstract: Species of structures were introduced by André Joyal and his group in Québec in the 1980s. They provide a way of organizing classes of labeled combinatorial objects that elevate the art of studying their generating functions to a science.

Combinatorial relationships realized bijectively among such classes are transformed into functional relationships of their generating functions. For example, from the combinatorial interpretation of a set partition as a set of non-empty sets, the exponential generating function for Bell numbers exp(exp(z)-1) becomes blindingly clear; exp(z) is the generating function of sets and exp(z)-1 that of non-empty ones.

I will discuss species of structures and some generating functions that are associated with them. I will explain how algebraic operations on generating functions can be seen to arise from set-theoretic operations on species. I will introduce the Frobenius characteristic generating function of a species of structures, which is a simple variation of the cycle index generating function, landing us in the world of symmetric polynomials.

About the Speaker: Amritanshu Prasad is a Professor of Mathematics in The Institute of Mathematical Sciences (IMSc), Chennai. His research interests are in Combinatorics and Representation theory. He is the recipient of many honors, including the  Swarnajayanti Fellowship, DST, (2014-15), and the Young Scientist Medal, Indian National Science Academy (2010). He is a Fellow of the Indian Academy of Sciences. He is the author of the book Representation Theory: A Combinatorial Viewpoint, Cambridge University Press (2015).

YouTube Live-Streaming Link https://youtu.be/z90RgmWPmqY


September 14
4:30 pm - 5:30 pm


Department of Mathematics


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