Variety (cybernetics)

In cybernetics , an increase (growing stock) of possibilities for action, action and communication of a system is described with the concept of increasing variety. According to W. Ross Ashby , the variety is used to measure the complexity of a system.

Variety theorem

The variety theorem describes the relationships between disturbances S that act on a system, the possible system reactions R and the resulting consequences K:

${\ displaystyle V_ {k}> = V_ {S} / V_ {R}}$

that is, the variety of consequences cannot be less than the ratio of the varieties of disturbances and the possible reactions.

Variety number and degree of variety

To this was added by Frahm Varietätszahl and Varietätsgrad introduced. Both variables are used to measure the complexity in cybernetics and are defined as follows:

- The variety number:

This describes the quotient of the sum of all interrelationships W of a project structure to the number of organizational levels OE.

${\ displaystyle V_ {Z} = SumW / SumOE}$

- The degree of variety:

This is the quotient of the sum of all interrelationships W to the number of nodes K in the project structure.

${\ displaystyle V_ {G} = SumW / SumK}$

Individual evidence

^ W. Ross Ashby : An Introduction to Cybernetics (= University Paperbacks. 80). Reprinted Edition. Chapman & Hall et al., London 1971, ISBN 0-412-05670-4 .
^ Michael Frahm: Description of complex project structures. In: Current project management. Vol. 22, No. 2, 2011, ZDB -ID 2074596-5 , pp. 22-27.

[1] W. Ross Ashby : An Introduction to Cybernetics (= University Paperbacks. 80). Reprinted Edition. Chapman & Hall et al., London 1971, ISBN 0-412-05670-4 .

[2] Michael Frahm: Description of complex project structures. In: Current project management. Vol. 22, No. 2, 2011, ZDB -ID 2074596-5 , pp. 22-27.