Null references redux

[BCS]

Hello bearophile,

> Do you know fuzzy logic? One of the purposes of fuzzy logic is to
> design control systems (that can be used for washing machines,
> cameras, missiles, etc) that work and fail gracefully. They don't work
> in two binary ways perfect/totallywrong. A graceful failure may have
> avoided the Ariane to crash and go boom.
> 
> Today people are studying software systems based on fuzzy logic,
> neural networks, support vector machines, and more, that are designed
> to keep working despite some small problems and faults.

But this still assumes some degree of reliability of the code doing the fuzzy 
logic. If I had to guess, I'd expect that the systems you mention are designed 
to function under external faults (some expected input vanishes or some other 
component in a distributed system fails). It would be almost impossible to 
make a program that can work correctly once it has had an internal fault. 
Once that has happened, I think Walter is correct and the only thing to do 
is shut down. In the auto pilot case, this could amount to kill off the current 
auto pilot process and boot up a very simple fly-straight-and-level program 
to take over while the pilot reacts to a nice loud klaxon.