Minimize Intellectual Distance

Edsger Dijkstra defined intellectual distance as the distance between the real-world problem and the computerized solution to that problem. Richard Fairley argues that the smaller the intellectual distance, the easier it will be to maintain the software.

To do this, the structure of the software should as closely as possible mimic the structure of the real world. You can minimize intellectual distance using any design approach. Be aware that the structure of the real-world is not unique. As pointed out so well by Jawed Siddiqi in his March 1994 article in IEEE Software, entitled "Challenging Universal Truths of Requirements Engineering," different people often perceive different structures when examining the same thing and thus construct quite diverse constructed realities.

Keep Design Under Intellectual Control

A design is under intellectual control if it has been created and documented in a manner that enables its creators and maintainers to fully understand it.

An essential attribute of such a design is that it is constructed hierarchically and with multiple views. Hierarchies enable readers to comprehend the entire system abstractly, and then comprehend finer and finer levels of details as they move down the hierarchy. At each level the component should be described from an external point of view only. Furthermore, any single component (at any level in the hierarchy) should exhibit simplicity and elegance.