In my talk I am going to remind you what is the AK-invariant and give examples of its usefulness. I shall also discuss basic conjectures about this invariant and some positive and negative results related to these conjectures.
Let be a proper smooth variety over a field of characteristic and an effective divisor on with multiplicity. We introduce a generalized Albanese variety Alb of of modulus , as higher dimensional analogue of the generalized Jacobian with modulus of Rosenlicht-Serre. Our construction is algebraic. For we give a Hodge theoretic description.
On étudie la relation entre le -rang des variétés abéliennes en caractéristique et la stratification de Kottwitz-Rapoport de la fibre spéciale en de l’espace de module des variétés abéliennes principalement polarisées avec structure de niveau de type Iwahori en . En particulier, on démontre la densité du lieu ordinaire dans cette fibre spéciale.
For a complex projective manifold Gromov-Witten invariants can be constructed either algebraically or symplectically. Using the versions of Gromov-Witten theory by Behrend and Fantechi on the algebraic side and by the author on the symplectic side, we prove that both points of view are equivalent
Let K,R be an algebraically closed field (of characteristic zero) and a real closed field respectively with K=R(√(-1)). We show that every K-analytic set definable in an o-minimal expansion of R can be locally approximated by a sequence of K-Nash sets.
Given a pseudo-effective divisor we construct the diminished ideal , a “continuous” extension of the asymptotic multiplier ideal for big divisors to the pseudo-effective boundary. Our main theorem shows that for most pseudo-effective divisors the multiplier ideal of the metric of minimal singularities on is contained in . We also characterize abundant divisors using the diminished ideal, indicating that the geometric and analytic information should coincide.
The double point relation defines a natural theory of algebraic cobordism for bundles on varieties. We construct a simple basis (over ) of the corresponding cobordism groups over Spec() for all dimensions of varieties and ranks of bundles. The basis consists of split bundles over products of projective spaces. Moreover, we prove the full theory for bundles on varieties is an extension of scalars of standard algebraic cobordism.
We show that the Beauville’s integrable system on a ten dimensional moduli space of sheaves on a K3 surface constructed via a moduli space of stable sheaves on cubic threefolds is algebraically completely integrable, using O’Grady’s construction of a symplectic resolution of the moduli space of sheaves on a K3.