Fig. 2.
An abstract environment that represents the events E, situations S, actions A and in which situations which events are present (black square) or absent (white square) and which actions are satisfactory (dark gray) or not (light gray)
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.