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53Systems

Ashby's Law of Requisite Variety

Only variety can absorb variety.

If

A controller can regulate a system only if it can match the variety of states that system can produce. Under-powered control simply cannot cope with a sufficiently rich environment.

Then

When incidents keep escaping your alerts and runbooks, either add matching response capability or deliberately shrink the system's state space: fewer configurations, stricter inputs.

Unless

Constrain the Environment — excess control variety is itself cost and complexity

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