ABSTRACT
Consider a system as shown in Figure 4.1 where a Control System controls an Application.
The Control System receives a number of stimuli (Inputs) from the Application and produces actions (Outputs) to affect the application. The control system realizes the control using simple logical conditions of the form:
If (Input Conditions) Then Outputs
The input conditions are logical expressions formulated according to Boolean algebra. Some examples of Input conditions:
valve_open valve_open OR timer_expired valve_closed AND temperature_ok
where OR and AND are logical operators. All arguments in these expressions are Boolean values (
false
,
true
). In the approach presented in the book we will expand the range of values in input conditions beyond the Boolean values and therefore the NOT operator will not be used.
