Subsystem optimisation and system optimisation

By Gordon Rugg

When a politician or a manager tells you that they’re going to take a “common sense” approach to a problem, they usually mean that they’re about to take a concept that works in one area, and apply it to a different area on the unstated assumption that it will work there too. Once in a while, it actually does. A lot of the time, though, it ends less than well.

There’s a technical description for one common way in which this approach comes to grief.

Sub-system optimisation does not necessarily lead to system optimisation.

It’s not exactly the most catchy line ever written, which might be why it’s not as widely known as it should be. This article is about what it means, and why it’s important.

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