Re: DNA and Information


"r norman" <r_s_norman@xxxxxxxxxxxx> wrote in message news:886893hrbgh97jronj4gdkvot8iuc0btae@xxxxxxxxxx
On Tue, 10 Jul 2007 22:48:50 GMT, "Perplexed in Peoria"
<jimmenegay@xxxxxxxxxxxxx> wrote:


"r norman" <r_s_norman@xxxxxxxxxxxx> wrote in message news:n5v793ldb52dvdr36mi9j2slp1q2t2bt2j@xxxxxxxxxx
On Tue, 10 Jul 2007 20:27:09 GMT, "Perplexed in Peoria"
<jimmenegay@xxxxxxxxxxxxx> wrote:

<snip because I prefer short posts restricted to a single point (even
though I frequently write very long and rambling posts without any
point)>

I am not arguing about an information processing system at all. I
think I will refuse to be drawn into that trap set by the philosophers.

There can be no 'information' in anything without a context that gives
the information its informational value.

First response: sez you.
Second response: Who said information has to have value?

[snip because the rest is only relevant if I buy into the idea that
'information' has to have 'value']

Let me try here to provide a first draft of something which I will
probably have to say at some point in my series.

INFORMATION DOES NOT HAVE TO INFORM!!!!!!

Gee, I feel much better now. Allow me to amplify on that a little:

INFORMATION DOES NOT HAVE TO INFORM!!!!!! REALLY!!!!!

The definition of 'information' and 'information theory' itself
do indeed originate in an analysis of situations in which someone
or something really is being informed in some way. But, having
started here, it has moved on. The same definitions and the same
theorems apply in other circumstances - sometimes related in some
manner to questions of knowledge and meaning, and sometimes not.

I will define 'information' as anything which can be measured in
bits (or nats) and I will define information theory as the discipline
which talks about such things.

It may have started having something to do with 'informing', but now
it doesn't necessarily. And nobody should find anything to object
to in this except maybe UC.

Ecologists often use a "Shannon measure" is an indication of the
diversity of an ecosystem. It uses the Shannon formula for measuring
information content (sum of p log p) on species population size. Does
that mean that each ecosystem contains information in a specified
number of bits?

In this formula, is 'p' actually a population size?!

Or is it rather a ratio of the population size to the sum of the sizes
of the populations of all species? That would make more sense as
a metric of diversity. Though I would approve even more if it were
a ratio of species biomass to total ecosystem biomass.

Actually, I would prefer to call that measure an 'informational entropy'
rather than an amount of information per se. (As, of course did
Shannon when he applied that formula to information. His formula
for the information content of a string or sequence would have
been (sum of log p). If you were to insist on a classically
informational interpretation of that particular diversity measure,
it might be the average number of bits required to represent species ID
in a database of every individual organism in the ecosystem. That is,
of course, highly artificial.

I may have to back off a little from my claim that everything measured
in bits should be thought of as information. After all, information
capacities are also measured in bits. But I would definitely assert
that those ecologists are applying information theory.

.

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