activity
20242026
collaborators

8 papers

math.AG2026

A note on the Nielsen realization problem for Enriques manifolds

Simone Billi

We give a numerical criterion for the Nielsen realization problem for Enriques manifolds, based on the recent developments on the Birman-Hilden theory for hyper-Kähler manifolds a…

math.AG2026

Some remarks on L-equivalence for cubic fourfolds and hyper-Kähler manifolds

Simone Billi, Lucas Li Bassi

We prove that if two very general cubic fourfolds are L-equivalent then they are isomorphic, and we observe that there exist special cubic fourfolds which are L-equivalent but not…

math.AG2026

On maximality of involutions of hyper-Kähler manifolds and punctual Hilbert schemes of surfaces

Simone Billi, Lie Fu, Annalisa Grossi +1

Given a holomorphic or anti-holomorphic involution on a complex variety, the Smith inequality says that the total -Betti number of the fixed locus is no greater than…

math.AG2025

Cubic fourfolds with a symplectic automorphism of prime order

Simone Billi, Annalisa Grossi, Lisa Marquand

We determine the algebraic and transcendental lattices of a general cubic fourfold with a symplectic automorphism of prime order. We prove that cubic fourfolds admitting a symplect…

math.AG2025

Non-existence of Enriques manifolds from OG10 type manifolds

Simone Billi, Franco Giovenzana, Luca Giovenzana +1

We use the LLV algebra to describe the action of a finite order automorphism on the total cohomology of a manifold of OG10 type. As an application, we prove that no Enriques manifo…

math.AG2025

A note on the Nielsen realization problem for hyper-Kähler manifolds

Simone Billi

We give an answer to the Nielsen realization problem for hyper-Kähler manifolds in terms of the same invariant used for K3 surfaces. We determine that, for some of the known defor…