Group Extensions (Mathematics), Mathematics / Algebra / Abstract, Mathematics / Group Theory, Representations of groups
The aim of these notes is a unified treatment of various group-theoretic topics for which, as it turns out, the Schur multiplicator is the key. At the beginning of this century, classical projective geometry was at its peak, while representation theory was growing in the hands of Frobenius and Burnside. In this climate our subject started with the two important papers of Schur on the projective representations of finite groups.