Topological invariants of O'Grady's six dimensional irreducible symplectic variety

Abstract

We study O'Grady examples of irreducible symplectic varieties: we establish that both of them can be deformed into lagrangian fibrations. We analyse in detail the topology of the six dimensional example: in particular we compute its Euler characteristic and determine its Beauville form.

35 pages, corrected a computational mistake in Theorem 3.5.1, improved exposition