Python from Wise Guy's Viewpoint

[Pascal Bourguignon]

Garry Hodgson <garry at sage.att.com> writes:

> Pascal Bourguignon <spam at thalassa.informatimago.com> wrote:
> 
> > You're  right, I  did not  answer.  I  think that  what is  missing in
> > classic software, and that ought to be present in AI software, is some
> > introspective  control:  having  a  process checking  that  the  other
> > processes are  live and  progressing, and able  to act to  correct any
> > infinite loop,  break down  or dead-lock.  
> 
> so assume this AI software was running on Ariane 5, and the same
> condition occurs.  based on the previously referenced design 
> assumptions, it is told that there's been a hardware failure, and that 
> numerical calculations can no longer be trusted.  how does it cope 
> with this?

I just read yesterday an old  paper by Sussman about how they designed
a  Lisp  on a  chip,  including the  garbage  collector  and the  eval
function.  Strangely enough that did not included any ALU (only a test
for zero and an incrementer, for address scanning).

You can  implement an  eval without arithmetic  and you  can implement
theorem prover above it still  without arithmetic.  You can still do a
great deal of thinking without any arithmetic...


> > Some  hardware may  help in
> > controling  this controling  software, like  on the  latest Macintosh:
> > they automatically restart when the system is hung. 
> 
> in this case, a restart would cause the same calculations to occur,
> and the same failure to be reported.

In this case, since the problem was not in the supposed AI controlling
agent, there would have been no restart.


> > And purely at the
> > hardware level,  for a real  life system, you  can't rely on  only one
> > processor.
> 
> absolutely right.  though, in this case, this wouldn't have helped either.
> the fatal error was a process error, and it occurred long before launch.

I think it would have  been helped.  For example, an architecture like
the  Shuttle's where  there are  five computer  differently programmed
would have  helped, because  at least one  of the computers  would not
have had the Ariane-4 module.

-- 
__Pascal_Bourguignon__
http://www.informatimago.com/