Geometry Seminar

Date: March 1, 2019

Time: 4:00PM - 5:00PM

Location: BLOC 628

Speaker: Visu Makam, IAS

Title: Exponential degree lower bounds for invariant rings

Abstract: The ring of invariants for a rational representation of a reductive group is finitely generated and graded. We give a general technique that can be used to show that an invariant ring is not generated by invariants of small degree. The main ingredients are Grosshans principle and the moment map, which I will explain. As an example, we apply this technique to show "exponential" lower bounds for the action of SL(n) on 4-tuples of cubic forms.