An interesting archive article on the topic of correctness, and the layers thereof:
Program verification: the very idea; Communications of the ACM Volume 31 , Issue 9 (September 1988) Pages: 1048 - 1063 Year of Publication: 1988 ISSN:0001-0782 "The notion of program verification appears to trade upon an equivocation. Algorithms, as logical structures, are appropriate subjects for deductive verification. Programs, as causal models of those structures, are not. The success of program verification as a generally applicable and completely reliable method for guaranteeing program performance is not even a theoretical possibility." And: The proof of correctness wars; Communications of the ACM archive Volume 45 , Issue 8 (August 2002) COLUMN: Practical programmer Pages: 19 - 21 Year of Publication: 2002 ISSN:0001-0782 "Whether mild or raging, wars about topics ranging from programming languages to methods of indentation are healthy for our field" One central point in the discussions is that the correctness of a (running) program is different than just that of a piece of code - it also depends on the compiler, OS, and underlying hardware layers. -- http://mail.python.org/mailman/listinfo/python-list