Certainty Factors

Hi,
I'm just wondering what angle the proposed RDF spec takes for dealing
with uncertainty, and the 'truth' of a statement. As an extreme case
let's have the assertion in one place (abstracting it a bit)

Object : Freddy's cat
Attribute : Colour
Value : Red

 and elsewhere we have the assertion
Object : Freddy's cat
Attribute : Colour
Value : Green

As I see it, there are essentially two approaches available - 1. there
is no need for implicit definition of certainty within RDF; 2. certainty
can be expressed in a RDF triple.

With 1, it could be left to a reasoning engine to determine which of
these statements is more likely to be true - following a chain of
authority perhaps, if the chain leads back to a document with Freddy as
the author, then we take his word on it.

With 2, we could have additional assertions along the lines of :

Object : The first statement about the colour of Freddy's cat
Attribute : Certainty
Value : 0.9

or even

Object : This document
Attribute : Certainty
Value : 0.01

Any thoughts on this?

I must confess that my knowledge of RDF is pre-pubescent, and apologies
if I've missed a relevant thread or document.

Cheers,
Danny.











 Having looked at other knowledge representation methods in the past 



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