Strongly regular and pseudo geometric graphs

Very often, strongly regular graphs appear associated with partial geometries. The point graph of a partial geometry is the graph whose vertices are the points of the geometry and adjacency is defined by collinearity. It is well known that the point graph associated to a partial geometry is a strongly regular graph and, in this case, the strongly regular graph is named geometric. When the parameters of a strongly regular graph, Γ, satisfy the relations of a geometric graph, then Γ is named a pseudo geometric graph. Moreover, it is known that not every pseudo geometric graph is geometric. In this work, we characterize strongly regular graphs that are pseudo geometric and we analyze when the complement of a pseudo geometric graph is also pseudo geometric.