The small index property for infinite dimensional classical groups
Let V be a vector space of countably infinite dimension over a finite field F, and G a symplectic, orthogonal, or unitary group on V. The main result in this paper is a description of all subgroups of G of index less than \(2^{\omega}\).
symplectic, orthogonal, or unitary group
scientific article; zbMATH DE number 4190029