On Sun, 20 Jul 1997 Mark Crosby <crosby_m@rocketmail.com> Wrote:
>That "all information is not of equal value" implies meaning, or
>semantics. The AIC and "depth" measures are strictly syntactic.
>Semantics basically involves categorization and context.
I don't think the two are as strictly segregated as some think and I don't
you need humans of even intelligence for semantics. A sequence of amino acids
MEANS a shape, the way the resulting protein folds up in water at the
temperature and acidity found in life.
>In the most general terms, it seems to me that complexity could be
>measured by the number of different functional relationships a
>system can maintain, and might further be weighted by the number of
>functions it can perform simultaneously.
Not a useful definition because we can't know how many relationships a
system can have.
>The temperate forest is more resilient than the tropical forest by
>whose measure (survivability against current human agricultural
>practices?)
No, surviving largely unchanged in the face of any environmental change,
not just those produced by humans.
>What is "the same thing" that these two types of forests do
Survive.
>the more complex program, which might have much more parameterization
>and be more data-driven by looking up values in external files, is
>going to be more flexible and possibly more maintainable.
I can not agree, at least not in general. If will be difficult to even
understand how a complex program works and without that you can't be sure
that any change you make in it won't have unexpected consequences.
>Bruce Edmonds:
>Complexity . . . is unlikely to have any useful value as applied to
>"real" objects or systems. Further that even relativising it to an
>observer has problems. It is proposed that complexity can usefully
>be applied only to constructions within a given language.
A language doesn't need an observer, consider the Genetic code. The nucleotide
triplet CAU in messenger RNA is a "real" object it MEANS the amino acid
histidine but I grant you, only in the context (language) of life, their are
no special chemical characteristics that relate one to the other. One type of
transfer RNA has an anticodon that connects to the CAU triplet of messenger
RNA like a key fitting into a lock. At another part of the transfer RNA
molecule, an amino acid can be attached, in this case histidine. However
transfer RNA can't tell one amino acid from another, the amino acid
attachment part is IDENTICAL in all tRNA molecules, but in practice, only
those that have the anticodon for CAU are attached to histidine. The reason
for this is an enzyme ( aminocyl-tRNA synthetase).
This enzyme can tell one amino acid from another, and it can tell one tRNA
molecule from another, and it can a attach a animo acid to it. However, this
enzyme does NOT look at the anticodon at all but at another part of the
transfer RNA, the DHU loop. In the lab the DHU loop from one type of tRNA has
been grafted onto another type of tRNA and that changes the genetic code.
It's also interesting that this enzyme is a protein encoded by, what else,
the genetic code. I can't point to exactly where the genetic code is, because
it does not reside in any one of these stages, it resides in all of them.
>A definition of complexity is proposed which can be summarised as
>"that property of a language expression which makes it difficult to
>formulate its overall behaviour even when given almost complete
>information about its atomic components and their inter-relations.
This could be AIC or depth, I can't tell which because Edmonds doesn't
say what he means by "difficult". At any rate, by this definition the
gibberish produced by a monkey would certainly be more complex than any
article in the journal "Nature". I want a definition that is not the opposite
of our intuitive understanding of the word, I haven't found it.
John K Clark johnkc@well.com
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