Path: utzoo!attcan!uunet!husc6!mailrus!tut.cis.ohio-state.edu!bloom-beacon!FRODO.STANFORD.EDU!golden
From: golden@FRODO.STANFORD.EDU (Richard Golden)
Newsgroups: comp.ai.digest
Subject: Re: Definition of Information
Message-ID: <19880615061544.6.NICK@INTERLAKEN.LCS.MIT.EDU>
Date: 15 Jun 88 06:15:00 GMT
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Date: Tue, 14 Jun 88 10:52 EDT
From: Richard Golden <golden@frodo.STANFORD.EDU>
To: AIList-REQUEST@AI.AI.MIT.EDU
Subject: Re: Definition of Information

In AILIST Digest V7 #26 Bruce Nevin asks:
Can anyone point me to a coherent definition of information respecting
information content, as opposed to merely "quantity of information"?

This question is really related to an earlier discussion concerned with
viewing probability theory as a measure of belief.  We can think of a
knowledge structure as being represented by a probability distribution
which assigns some "degree of belief" (i.e., a probability) to some
set of events (i.e., a sample space).  Let X be an event which occurs 
with probability p(X).  Then clearly an equivalent "knowledge structure"
which assigns some "degree of surprise" (i.e., -LOG[p(X)]) to some
set of events (i.e., a sample space) may be constructed.

The simple point which I am making is that the SAMPLE SPACE and the
STRUCTURE OF ITS ELEMENTS is a necessary component of the definition of
information in a technical sense and information CONTENT (for the most
part) resides in this SAMPLE SPACE.

					Richard Golden (golden@psych)