Strong Identification Codes for Graphs

Abstract

For any graph~\(G,\) a set of vertices~\({\cal V}\) is said to be dominating if every vertex of~\(G\) contains at least one node of~\(G\) and separating if each vertex~\(v\) contains a unique neighbour~\(u_v \in {\cal V}\) that is adjacent to no other vertex of~\(G.\) If~\({\cal V}\) is both dominating and separating, then~\({\cal V}\) is defined to be an identification code. In this paper, we study strong identification codes with an index~\(r,\) by imposing the constraint that each vertex of~\(G\) contains at least~\(r\) unique neighbours in~\({\cal V}.\) We use the probabilistic method to study both the minimum size of strong identification codes and the existence of graphs that allow an identification code with a given index.