2010 Mathematics Subject Classification: 05E30, 05C50;

Abstract: Divisible design graphs (DDG for short) have been recently defined by Kharaghani, Meulenberg and the second author as a generalization of (v, k, λ)-graphs. In this paper we give some new constructions of DDGs, most of them using Hadamard matrices and (v, k, λ)-graphs. For three...

AMS Subject Classification: 05B05, 05E30, 05C50.

Рассматриваются модели унифицированного информационного управления в социальных сетях, описываемых регулярным графом взаимодействия их членов. Основной...

AMS classifications: 05E30, 05B20;

The energy of a graph is the sum of the absolute values of the eigenvalues of its adjacency matrix. Koolen and Moulton have proved that the energy of a graph on n vertices is at most n(1 + √n)/2, and that equality holds if and only if the graph is strongly regular with parameters (n,...