Rational points and cohomology of discriminant varieties

Rational points on varieties

Rational Points and Coxeter Group Actions on the Cohomology of Toric Varieties

We derive a simple formula for the action of a finite crystallographic Coxeter group on the cohomology of its associated complex toric variety, using the method of counting rational points over finite fields, and the Hodge structure of the cohomology. Various applications are given, including the determination of the graded multiplicity of the reflection representation.

Rational Points of Rationally Simply Connected Varieties

These are notes prepared for a series of lectures at the conference Variétés rationnellement connexes: aspects géométriques et arithmétiques of the Société Mathématique de France held in Strasbourg, France in May 2008.

Varieties with Too Many Rational Points

We investigate Fano varieties defined over a number field, which contain subvarieties whose number of rational points of bounded height is comparable to the total number on the variety.

Counting Rational Points on Algebraic Varieties

In these lectures we will be interested in solutions to Diophantine equations F (x1, . . . , xn) = 0, where F is an absolutely irreducible polynomial with integer coefficients, and the solutions are to satisfy (x1, . . . , xn) ∈ Z. Such an equation represents a hypersurface in A, and we may prefer to talk of integer points on this hypersurface, rather than solutions to the corresponding Diophan...