Software Development is an Empirical Process

nZiv's Uncertainty Principle in Software Engineering - uncertainty is inherent and inevitable in software development processes and products [Ziv, 1996]. nHumphrey's Requirements Uncertainty Principle - for a new software system, the requirements will not be completely known until after the users have used it. nWegner's Lemma - it is not possible to completely specify an interactive system [Wegner, 1995].