"Tim Tyler"  wrote in message
news:c5ut04$2rpg$1{at}darwin.ediacara.org...
> irr  wrote or quoted:
> > "Tim Tyler"  wrote in message
> > > IRR  wrote or quoted:
>
> > > The best-established way of measuring complexity is to use Kolmogorov
> > > complexity.
> > >
> > > This:
> > >
> > > * Confines discussion to digital phenomena;
> > > * Is difficult to measure;
> > > * Has a subjective element - since it depends on a choice of
> > >   descriptive language.
> > >
> > > The first is no problem, if we are content to confine ourselves
> > > to the complexity of genomes.
> > >
> > > The second is a problem in theory:
> > >
> > > * Except in a few trivial cases, you can only put bounds on the
metric -
> > >   rather than measure it exactly (and even then the lower bound is
rarely
> > >   much use).  I would suggest ignoring this problem - and measuring
> > >   the value using a conventional high-quality compressor of a type
> > >   that is capable of dealing well with repeated sequences.
> > >
> > > ...and in practice...
> > >
> > > * You need to sequence the genome in question before you can measure
> > >   its complexity;
> > >
> > > The third makes the metric less asethetically attractive.  My approach
> > > would probably be to say something along the lines of:
> > >
> > > "Always use FORTRAN-77 as your language".
> > ....]
> >
> > IMO this third problem -- choosing a language with which to quantify
> > complexity -- is still *the* showstopper when it comes to biology.
>
> I like the answer I gave.
>
> I almost always give this answer.
>
> So far - IMO - I have had no serious complaints ;-)

Better check your audience ;-).

>
> There may be a few even more "unbiased" languages out there -
> but FORTRAN-77 is convenient enough.
>
> > While we might all agree that the primate brain is an incredibly
> > complex organ, it's not at all agreed upon what it is we mean by this.
> > For example, a Kolmogorov measure fails miserably in classifying the
> > brain as complex, after all you're really only talking about two dozen
> > or so different recognized cell types stamped out in enormous
> > repetition with iterated connections between them -- in other words, a
> > digital representation of the brain is incredibly compressible.
>
> IMO - this makes no sense at all :-|
>
> An acceptable digital version of the brain would handle the same I/O - and
> produce similar inputs from similar outputs.  This sounds like a job for
> a huge computer with an *extremely* lengthy description to me - and of
> course a correspondingly enormous Kolmogorov complexity.
> -- 
> __________
>  |im |yler  http://timtyler.org/  tim{at}tt1lock.org  Remove lock to reply.
>

Certainly a huge computer, but really an extremely lengthy description?
Check out the top 500 list (top500.org) -- the fastest computers in the
world are and will continue to be iterations of the single processor system
you're likely reading this reply on right now.  While such massively
parallel systems -- including the human brain -- are increadibly impressive
to look at, they are remarkably regular.  Kolmogorov essentially a measure
of regularity; low in highly parallel architectures and high in random ones.
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