Graphs
The spectral radius of a finite graph is defined to be the spectral radius of its adjacency matrix.
This definition extends to the case of infinite graphs with bounded degrees of vertices (i.e. there exists some real number C such that the degree of every vertex of the graph is smaller than C). In this case, for the graph let denote the space of functions with . Let be the adjacency operator of, i.e., . The spectral radius of G is defined to be the spectral radius of the bounded linear operator .
Read more about this topic: Spectral Radius