3 - Strongly Regular Graphs
from Part II - Graph Basics
Published online by Cambridge University Press: 05 June 2026
Summary
In this chapter we consider strongly regular graphs, an important class of graphs for many applications, which include both the Shrikhande graph and the graphs associated with Latin squares, all of which play a part in our story.
This theorem was proved by Erdős, Rényi and Sós in the 1960s. It was an early success for the methods of algebraic graph theory.
We assume that friendship is an irreflexive and symmetric relation on a set of individuals: that is, nobody is his or her own friend, and if A is B’s friend then B is A’s friend. (It may be doubtful if these assumptions are valid in the age of social media – but we are doing mathematics, not sociology.) In other words, the situation is described by a graph, in which the vertices are the individuals and two vertices are joined if they are friends.
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- The Shrikhande GraphA Window on Discrete Mathematics, pp. 37 - 56Publisher: Cambridge University PressPrint publication year: 2026
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