Sums of squares on surfaces

Series
Algebra Seminar
Time
Monday, November 6, 2023 - 1:00pm for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Gregory G. Smith – Queen's University – ggsmith@mast.queensu.ca
Organizer
Changxin Ding

Please Note: There will be a pre-seminar (aimed toward grad students and postdocs) from 11 am to 11:30 am in Skiles 006.

How do we effectively verify that a polynomial function is nonnegative?  One may certify nonnegativity by exhibiting a nonnegative multiplier such that the product is a sum of squares.  We will survey a few known results before focusing on some new degree bounds on multipliers.  Unexpectedly, our novel techniques are particularly well-suited to ruled surfaces.  This talk is based on joint work with Grigoriy Blekherman, Rainer Sinn, and Mauricio Velasco.