[adrianN]

> Also, since they're provably correct the "maintenance" metaphor is no longer applicable.

If you want your software to never change, then sure, a proof of correctness is enough. But I've yet to see a piece of software that is both relevant and never has to adapt to new requirements.

[verbin217]

Agreed. When I said "maintenance" I was referring to the continuous post hoc work needed to uphold the original functionality as it encounters the full range of it's potential input.