Nov-25-2018, 04:33 PM
(This post was last modified: Nov-25-2018, 04:33 PM by Gribouillis.)
You can start thinking about the data that describe the state of the system at a given moment. I would say this data comprises which buttons are lit in the lift, which buttons are lit on the floors, the lift's current position and direction. Then think about the events that may change this data.