Figure 1. An example of a node labeling.
A node labeling, 
, of the nodes of a network with 
nodes so that, for instance, 
and 
.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.