2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/71404We 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 expositionAlgebraic Geometrytext