Finite groups and complex projective surfaces
Alexander Lubotzky, Matthew Stover
TL;DR
The paper addresses realizing any finite group G as the automorphism group of a closed complex hyperbolic 2-manifold. It develops a construction that starts from cocompact nonarithmetic lattices in PU(2,1) with nontrivial universal homomorphisms and uses congruence-subgroup techniques to produce torsion-free subgroups whose normalizers realize G as a quotient, with Mostow rigidity identifying the automorphism group of the associated manifold with G. A key technical tool is a rigidity result for automorphisms of surface groups, ensuring control over induced automorphisms under the universal-homomorphism framework. The work yields infinitely many isomorphism classes for each G and also translates the results into the setting of irreducible smooth complex projective surfaces of general type, broadening the impact to complex algebraic geometry and the study of Kähler groups.
Abstract
In response to a question raised by Belolipetsky and the first author, we prove that for every finite group $G$ there are infinitely many isomorphism classes of compact complex hyperbolic $2$-manifolds with automorphism group isomorphic to $G$.
