Algebraic Geometry Seminar Spring 2015

The seminar meets on Fridays at 2:25 pm in Van Vleck B135.

The schedule for the previous semester is here.

Algebraic Geometry Mailing List

• Please join the Algebraic Geometry Mailing list to hear about upcoming seminars, lunches, and other algebraic geometry events in the department (it is possible you must be on a math department computer to use this link).

Fall 2014 Schedule

date	speaker	title	host(s)
February 20	Jordan Ellenberg (Wisconsin)	Furstenberg sets and Furstenberg schemes over finite fields	I invited myself
February 27	Botong Wang (Notre Dame)	TBD	Max
March 6	Matt Satriano (Johns Hopkins)	TBD	Max
March 13	Jose Rodriguez (Notre Dame)	TBD	Daniel

Abstracts

Jordan Ellenberg

Furstenberg sets and Furstenberg schemes over finite fields

We prove a theorem of Kakeya type for the intersection of subsets of n-space over a finite field with k-planes. Let S be a subset of F_q^n with the "k-plane Furstenberg property": for every k-plane V, there is a k-plane W parallel to V which intersects S in at least q^c points. We prove that such a set has size at least a constant multiple of q^{cn/k}. The novelty is the method; we prove that the theorem holds, not only for subsets of the plane, but arbitrary 0-dimensional subschemes, and reduce the problem by Grobner methods to a simpler one about G_m-invariant subschemes supported at a point. The talk will not assume that everyone in the room is an algebraic geometer.

Jose Rodriguez

TBA