Brooks's Law

Brooks's Law: prov.

“Adding manpower to a late software project makes it later�? — a result of the fact that the expected advantage from splitting development work among N programmers is O(N) (that is, proportional to N), but the complexity and communications cost associated with coordinating and then merging their work is O(N^2) (that is, proportional to the square of N).

The quote is from Fred Brooks, a manager of IBM's OS/360 project and author of The Mythical Man-Month (Addison-Wesley, 1975, ISBN 0-201-00650-2), an excellent early book on software engineering. The myth in question has been most tersely expressed as “Programmer time is fungible�? and Brooks established conclusively that it is not. Hackers have never forgotten his advice (though it's not the whole story; see bazaar); too often, management still does. See also creationism, second-system effect.