[Haskell-cafe] Re: Wikipedia on first-class object

Ketil Malde ketil+haskell at ii.uib.no
Sun Dec 30 03:38:36 EST 2007

jerzy.karczmarczuk at info.unicaen.fr writes:

> I suggest that you read something on 'quantum computing'. 

I guess I should disclaim the rest of my post right away: I don't know
much about quantum anything, beyond what I read in the newspapers.
Sorry.  But:

> Concerning quanta, the simulation of quantum processes on classical archi-
> tectures may be and usually is extremely inefficient. So inefficient that
> your "simulation" loses sense. 

You could raise the same argument for (digital) computers compared to
brains - although my brain might be able to, it's not practical for it
to do the computations performed even by simple computer programs.

But the difference is quantitative and practical, not qualitative and
theoretical.  (Arguably, I know. I invoke Occam.)

> No classical system can compute, say, a Fourier transform in
> constant (in fact, infinitely small) time, quantum system do it (in
> a sense) constantly.

If I understand correctly, a quantum computer might solve problems in
NP in polynomial time, which is assumed not to be possible for
deterministic computers.  As far as I can tell, it doesn't imply the
ability to compute anthing that wasn't computable before.

Now if we can wrap up the topic of whether machines can think, next
session we'll discuss whether ships can swim.

If I haven't seen further, it is by standing in the footprints of giants

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