Law of Requisite Variety

1. Subject: Management Information System
Topic: Ashby’s Law of Requisite Variety
Prepared By:
Mohammed Jasir PV
Asst. Professor
NBS, Koratty
Phone: 9605 69 32 66

2. • Assume that, a junction with many vehicles
• How we are controlling all these?
• By using a traffic signal light

3. • What will happen if there only one
light in the traffic signal?
• Is it possible to handle the same
situation?
• The control techniques which we
have is very less but the situation
need different controls

4. Which radio is best and why?

7. Law of Requisite Variety
• “Only variety absorbs variety”
• Rosh Ashby
• The variety of regulator has to match
with the variety of system

9. Law of Requisite Variety
• Law of requisite variety is one of the basic notation of system control theory,
to obtain control
• This has various rigorous formulations, but a commonsense, understanding is
that to control each possible state of system elements
• This means also that the control for the system must be able to determine of
variables and send system change instructions for each change
• The Law of requisite variety needs that for a system to be control, every
controller (human/machine) must be provided with enough control responses
(what to do in each case) to cover all possible condition the system may face

10. Contd…
• The law of requisite variety means that for a system to be controlled, every
controller(human and machine) must be provided with:-
1. Enough control responses (what to do in each case) to cover all possible
conditions the system may face
2. The decision rules for generating all possible control responses or
3. The authority to become a self organizing system in order to generate control
responses
• Enumerating all responses is possible in simple cases. In complex systems providing
control responses is very difficult

11. Thank You