On the model theory of higher rank arithmetic groups
arXiv:2008.01793
Abstract
Let be a centerless irreducible higher rank arithmetic lattice in characteristic zero. We prove that if is either non-uniform or is uniform of orthogonal type and dimension at least 9, then is bi-interpretable with the ring of integers. It follows that the first order theory of is undecidable, that all finitely generated subgroups of are definable, and that is characterized by a single first order sentence among all finitely generated groups.
preliminary version. Comments welcome