The Slice Method for torsors of algebraic groups

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• Mark MacDonald (Lancaster)
• Wednesday 13 November 2013, 14:15-15:15
• MR 13, CMS.

If you have a question about this talk, please contact Dr. J Ross.

Given a linear representation V of a linear algebraic group G, the slice method in invariant theory is a way of reducing birationality questions about V/G to questions about S/N(S), where S < V is a “slice”, and N(S) is its normalizer. I will describe how an analogous method could be applied to G-torsors over a field, to obtain a reduction to N(S)-torsors. This leads to new information about essential dimension. In this talk I will also give some context for the notion of essential dimension, and finally I will explain the various ways the slice method can be applied when G is the split exceptional algebraic group of type F_4, hence giving new bounds on ed(F_4).

This talk is part of the Algebraic Geometry Seminar series.

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