System behaviors: state machine diagrams

Capture the admissible behaviors of system components
Behavior of component instance = sequence of state transitions for the items it controls
SM state = set of situations where a variable characterizing a controlled item has always the same value e.g. state MeetingScheduled: always same value for Date, Location (while other variable WithWhom on Meeting may change value)
Initial, final states = states where item appears, disappears
States may have some duration
SM state transition: caused by associated event
if item in source state and event ev occurs
then it gets to target state
Events are instantaneous phenomena