Permuting the rows (and not the columns) of the adjacency matrix of a graph is called dual Seidel switching. This operation was introduced in [H84] as a possible way to construct strongly regular graphs with λ=μ from the existing ones.
A k-regular graph G on v vertices is a Deza graph with parameters (v,k,b,a), where v>k≥b≥a≥0, if the number of common neighbours of two distinct vertices takes on one of two values a or b, not necessarily depending on the adjacency of the two vertices. A Deza graph is called a strictly Deza graph if it has diameter 2 and is not strongly regular. In [EFHHH99], the dual Seidel switching was adopted to obtain strictly Deza graphs from strongly regular graphs.
In this talk we give a survey of results on Deza graphs obtained by the dual Seidel switching. This is joint work in progress with Sergey Goryainov and Vladislav V. Kabanov.