### Selberg’s lemma and negatively curved Hadamard manifolds

Selberg’s lemma is a fundamental result about linear groups. It states that every finitely generated subgroup of \(\mathrm{GL}(n,K)\), where \(K\) is a field of characteristic zero, is virtually torsion-free (i.e., contains a torsion-free subgroup of finite index). Recently, Michael Kapovich proved that the conclusion of Selberg’s lemma can fail for finitely generated, discrete subgroups of isometry groups … Continue reading "Selberg’s lemma and negatively curved Hadamard manifolds"

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