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.
Partition 
fully reflects the reference, 
(
). In contrast, partition 
is random with respect to the reference – the two results do not share any information (
). Partition 
is a combination of the two previous situations – half of the reference can be recovered from this clustering (
).
