|Date: Wednesday, November 08, 2017
Location: 4096 East Hall (4:10 PM to 5:30 PM)
Title: Motivic Euler numbers and an arithmetic count of the lines on a cubic surface
Abstract: A celebrated 19th century result of Cayley and Salmon is that a smooth cubic surface over the complex numbers contains exactly 27 lines. Over the real numbers, it is a lovely observation of Finashin-Kharlamov and Okonek-Teleman that while the number of real lines depends on the surface, a certain signed count of lines is always 3. We extend this count to an arbitrary field k using an Euler number in A1-homotopy theory. The resulting count is valued in the Grothendieck-Witt group of non-degenerate symmetric bilinear forms. This is joint work with Jesse Kass.
Speaker: Kirsten Wickelgren
Institution: Georgia Tech