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Adventures with group theory: counting and constructing polynomial invariants for applications in quantum entanglement and molecular phylogenetics

by

Dr Peter Jarvis


Date: Friday, June 8, 2012          Time: 15:10           Location: B.21 Ingkarni Wardli   

Abstract: In many modelling problems in mathematics and physics, a standard challenge is dealing with several repeated instances of a system under study. If linear transformations are involved, then the machinery of tensor products steps in, and it is the job of group theory to control how the relevant symmetries lift from a single system, to having many copies. At the level of group characters, the construction which does this is called PLETHYSM. In this talk all this will be contextualised via two case studies: entanglement invariants for multipartite quantum systems, and Markov invariants for tree reconstruction in molecular phylogenetics. By the end of the talk, listeners will have understood why Alice, Bob and Charlie love Cayley's hyperdeterminant, and they will know why the three squangles -- polynomial beasts of degree 5 in 256 variables, with a modest 50,000 terms or so -- can tell us a lot about quartet trees!

The Colloquium will be followed by a reception for our speaker in the Staff Tea Room with wine and nibbles to which all are invited.

Peter's web-page

Slides of his talk