1. Any given program, when running, is obsolete.
2. Any given program costs more and takes longer each time it is run.
3. If a program is useful, it will have to be changed.
4. If a program is useless, it will have to be documented.
5. Any given program will expand to fill all the availible memory.
6. The value of a program is inversely proportional to the weight of it's output.
7. Program complexity grows until it exceeds the capability of the programmer who must maintain it.
8. Every non-trivial program has a least one bug
Corollary 1 - A sufficient condition for program triviality is that is has no bugs.
Corollary 2 - At least one bug will be observed after the author has left the organization.
9. Bugs will appear in one part of a working program when another 'unrelated' part is modified.
10. The subtlest bugs cause the greatest damage and problems.
Corollary - A subtle bug will modify storage thereby masquerading as some other problem.