# Re: Abbreviated assertions (was: Certainty Factors)

From: Danny Ayers <Danny.Ayers@highpeak.ac.uk>
Date: Mon, 13 Dec 1999 12:26:31 +0000
Message-ID: <3854E5F7.A5070AFB@highpeak.ac.uk>
To: Daniel LaLiberte <liberte@w3.org>

```Hi,
You say '...what matters is what you *do* with assertions...' which
seems a little to be avoiding my question. My point is that for the
inference engine to use e.g. Bayesian reasoning, some facility for
certainty must be included. I'm a little uncertain (:-)) of your
notation, and could probably answer better if you could spell this out
for me. I'll try though, on the assumption that you are meaning
something along the lines of :

A --p--> B

could be
A = Freddy's cat
p = has colour
B = Red

B --q--> C

B = Red
q = type of colour
C = Primary

which could allow us to have

A --p--> x --q--> C

so I suppose --p-q--> could be equal to --p--> x --q-->

which is clear given the above example, but I'm not clear enough to see
whether this can be generalised.

But I'm slipping off my topic, so for the sake of argument let's say the
above is all fair enough, then as the assertions have no element of
uncertainty, then whatever you do with the assertions is fixed to this
same premise. If however you had the following
A --p--> B (probability 0.9)
B --q--> C (probability 0.9)

you could derive a probability for A --p-q--> C, so you could say 'there
is a 0.81 (or somesuch) probability that Freddy's cat is a primary
colour.

To keep with the 'assertions-only' approach I imagine this could be
expressed as :

[s1] - type -> rdf:Statement
[s1] - subject -> [Freddy's Cat]
[s1] - predicate -> [colour]
[s1] - object - > [Red]

[s2] - type -> rdf:Statement
[s2] - subject -> [s1]
[s2] - predicate -> [certainty]
[s2] - object - > [0.9]

but I was wondering whether this is adequate to cover all eventualities.
Is a rdf:Statement(probabilistic) type needed? Is there a better way of
expressing [s2]?

Cheers,
Danny.
```
Received on Monday, 13 December 1999 07:26:59 UTC

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