A survey of partial difference sets

LetG be a finite group of order . Ak-element subsetD ofG is called a (,k, , )-partial difference set if the expressionsgh ^–1, forg andh inD withgh, represent each nonidentity element inD exactly times and each nonidentity element not inD exactly times. IfeD andgD iffg ^–1D, thenD is essentially the same as a strongly regular Cayley graph. In this survey, we try to list all important existence and nonexistence results concerning partial difference sets. In particular, various construction methods are studied, e.g., constructions using partial congruence partitions, quadratic forms, cyclotomic classes and finite local rings. Also, the relations with Schur rings, two-weight codes, projective sets, difference sets, divisible difference sets and partial geometries are discussed in detail.