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.
and 
.
A multiplex network is a network where different layers share the same set of nodes and edges on each layer represent a different relationship. For example, here the nodes could represent countries in the world, the edges in layer U the alliances between them, and the edges in layer 
may denote trade between the same set of countries.
