Invisible wrote:
> Invisible wrote:
> 
>> This seems relevant:
>>
>> http://en.wikipedia.org/wiki/Rice%27s_theorem
>>
>> Now, if only it wasn't completely incomprehensible...
> 
> So, to summarise:
> 
>   For any property that some functions have and some functions don't 
> have, it is impossible to tell whether a given function has that 
> property just by examining the computer program that implements the 
> function.
> 
> (Or rather, for one specific program it might be possible, but it's not 
> possible for *every possible* program...)
> 
> Is that about right?

Yes, that sounds right to within the limits of english prose vs mathematics. 
:-) Pluralize "computer program" and you're a touch closer, since there can 
be many programs that implement the same function, but you can't tell what 
they are. ;-)

Basically, you can think of it as "you can turn any problem into the halting 
problem."  Anything that some programs do and some don't, you can turn into 
the halting problem.

-- 
   Darren New, San Diego CA, USA (PST)
   "We'd like you to back-port all the changes in 2.0
    back to version 1.0."
   "We've done that already. We call it 2.0."

Post a reply to this message