Notes

Equivariant Intersection Theory

The following are notes from William Fulton's Eilenberg lectures on "Equivariant Cohomology in Algebraic Geometry."

Eilenberg lectures, Columbia University, Spring 2007.

Some of the following might eventually be polished enough to be posted.  In the meantime, feel free to ask me if you're interested.

William Graham showed that the structure constants of the equivariant cohomology of a (generalized) flag variety are positive in the roots.  This note gives a short, geometric proof, based on a transversality argument.  (April 2007)

These are notes from an expository talk given at Columbia, to accompany Bill Fulton's lecture series.  (April 2007)  (Comments welcome on the current draft!)

This article gives a geometric explanation for a certain polynomial identity relating double Schubert polynomials to single ones, together with some generalizations to other Lie types. As Allen Knutson kindly pointed out to me, experts were already familiar with the main results, but I do not know a good reference in the literature.  (June 2006)

In the cohomology of the complex flag manifold, Schubert classes have particularly nice polynomial representatives, called Schubert polynomials.  It turns out that the same is true in the manifold of real flags, when you take mod 2 coefficients; these notes explain why.  (April 2005)

From a talk given at the Student Algebraic Geometry Seminar on November 18, 2005.

From a talk given at the Tropical Geometry Seminar on October 6, 2005.

From a talk given at the Student Algebraic Geometry Seminar on February 8, 2005.

Notes from a talk given at the Student Topology Seminar on November 19, 2004.

I spent the summer of 2001 under the mistaken impression that I wanted to be a physicist.  The time wasn't completely wasted, though: I learned something about Feynman integrals, and played some incredible Capture-the-Flag.