Schur Multiplier

In mathematical group theory, the Schur multiplier or Schur multiplicator is the second homology group H2(G, Z) of a group G. It was introduced by Issai Schur (1904) in his work on projective representations.

Read more about Schur Multiplier:  Examples and Properties, Relation To Projective Representations, Relation To Central Extensions, Relation To Efficient Presentations, Relation To Topology, Applications