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.
Example of an area, points, and cells. This area is a polygon composed by points a0, a1, …, and a5. To this area, point p1 and point p3 are not-inside and point p2 is inside, both cells c1 and c2 are overlapped and c3 is not overlapped. Moreover, cell c1 is also termed as inside this area.
