Let G = (V,E) be a regular graph with v vertices and degree k. G is said to be strongly regular if there are also integers λ and μ such that:
A graph of this kind is sometimes said to be an srg(v,k,λ,μ).
Some authors exclude^{[citation needed]} graphs which satisfy the definition trivially, namely those graphs which are the disjoint union of one or more equalsized complete graphs, and their complements, the Turán graphs.
A strongly regular graph is a distanceregular graph with diameter 2, but only if μ is nonzero.
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