On the definition of irreducible holomorphic symplectic manifolds and their singular analogs
arXiv:2003.06004
Abstract
In the definition of irreducible holomorphic symplectic manifolds the condition of being simply connected can be replaced by vanishing irregularity. We discuss finite quotients X of complex tori where the space of reflexive 2-forms is generated by a holomorphic symplectic form, and their Lagrangian fibrations. Neither X nor the base can be smooth unless X is a 2-torus.
10 pages