Degree diameter problem

The Degree-Diameter Problem (DDP) is a classic problem in the field of graph theory and combinatorics. It focuses on the trade-off between the degree of vertices in a graph and its diameter. Specifically, the problem seeks to determine the maximum number of vertices \( N \) in a graph given two constraints: the maximum degree \( D \) of any vertex and the maximum diameter \( h \) of the graph.