change when we change software Reflecting on Lehman's categories of software system Nat Pryce @natpryce [email protected] github.com/npryce speakerdeck.com/npryce
a theory of a model of an abstraction of some portion of the world or of some universe of discourse. –Manny Lehman Programs, Life Cycles, and Laws of Evolution. 1980
real-world problem but does not affect the world it models Embedded in the world it models; its operation changes that world S-Type P-Type E-Type Lehman's categories of software system
real-world problem but does not affect the world it models S-Type P-Type Embedded in the world it models; its operation changes that world E-Type Lehman's categories of software system
real-world must change or become less and less useful in that environment. Law of Increasing Complexity As a system evolves, its complexity increases unless work is done to maintain or reduce it. –Manny Lehman (1974, ...)
multi agent feedback systems and: The outcome, in the real world, of software system operation is inherently uncertain with the precise area of uncertainty also unknown –Manny Lehman (1974 onwards)