Held group

In the area of modern algebra known as group theory, the Held group He is a sporadic simple group of order In the area of modern algebra known as group theory, the Held group He is a sporadic simple group of order He is one of the 26 sporadic groups and was found by Dieter Held (1969a, 1969b) during an investigation of simple groups containing an involution whose centralizer is isomorphic to that of an involution in the Mathieu group M24. A second such group is the linear group L5(2). The Held group is the third possibility, and its construction was completed by John McKay and Graham Higman. The outer automorphism group has order 2 and the Schur multiplier is trivial.