[jcelerier]

> It may not work perfectly in 100% of the cases, but that doesn't mean reversing a string is no longer possible.

I don't understand why in maths finding one single counter-example is enough to disprove a theorem yet in programming people seem to be happy with 99.x % of success rate. To me, "It may not work perfectly in 100% of the cases" exactly means "no longer possible" as "possible" used to imply that it would work consistently, 100% of the time.

[tux3]

It is very useful in engineering to do things that are mathematically impossible, by simply ignoring or rejecting the last 1%.

Sometimes that's unacceptable, because you really do care about 100% of cases. When it isn't, you get really cool "impossible" tools out of it :)

[paxys]

Because programming is not a science (or at most it is an applied science).

By your logic any software that has a single bug would be useless, and if that were the case this entire profession wouldn't exist.

[solarmist]

Because you have additional information that separates it from the general case.

Even in mathematics if you add additional constraints you can solve subclasses of problems.