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Re: Comments to Rules Working Group Charter Draft $Revision: 1.60$ (Part II)

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Mon, 12 Sep 2005 13:35:38 +0100
Message-ID: <4325761A.1010508@hplb.hpl.hp.com>
To: Giorgos Stamou <gstam@softlab.ntua.gr>
CC: "'Sandro Hawke'" <sandro@w3.org>, public-rule-workshop-discuss@w3.org

Giorgos Stamou wrote:

 >> [der]
>>Is this a question we could pose to the Semantic Web Best Practices
>>working group?
> 
> 
>  [Giorgos Stamou] 
> 
> Well, I think this is a good idea. And since I am a member of the Semantic
> Web Best Practices Working Group (also co-chairing a new Task Force on
> Multimedia Annotation in the Semantic Web, an area that needs uncertainty
> representation) I could certainly start this discussion there, as well.

That sounds good, thank you. I'll look forward to seeing how the discussion 
goes. I think the issue of how to handle uncertainty on the semantic web is 
a bigger question than how to generalize logical rules.

> The work on fuzzy logic has been started in 1965. And, in its late form (see
> the book [Petr Hayek, Metamathematics of Fuzzy Logic, Kluwer Academic
> Publishers 1998]), it is really a general framework covering several other
> relevant theories of multi-valued logic. It is a clear and sound framework.

I last used it in the early 80's so I'm aware it has been around for a while.

> Still, it is not complete! But I think most theories in logics are not
> "complete". I also think that the W3C Standardization process does not only
> cover "complete" theories. Moreover, there is no final "agreement" of the
> community that discusses the charter, in basic issues of classical logic
> (consider the example of the usefulness of monotonic or non-monotonic
> logic).
> So, I understand your argument but I don't really think that we are very
> confident with several other language extensions fairly included in the
> charter. Moreover, obviously I did not propose uncertainty for the core
> language. I only proposed to be included in the strongly-motivated in-scope
> extensions to be considered.

Perhaps you are right that uncertainty representation is as settled an 
issue as how to combine non-monotonic rules with RDF and OWL but the latter 
is hardly an uncontroversial issue :-)

 >> [der]
>>For good or ill, the emphasis of the draft charter is not on an
>>implementable language but on an interlingua for exchange of rules
>>between existing systems. It's not clear that the uncertainty use cases
>>really fall into the interlingua remit. I would have thought that the
>>issues of successful exchange and integration of rules involving
>>uncertainty reasoning would be much greater that those of simply using
>>fuzzy inference within a single system. Whereas the use cases seemed to
>>want an implemented language they could use without a particular need
>>for rule exchange.
> 
> 
> [Giorgos Stamou] 
> I think they fall in the same framework. In the case you have different rule
> systems dealing with uncertain and fuzzy rules, they should exchange these
> rules in a similar form, in order to be able to deliver the uncertainty and
> fuzziness.  

The point I was trying to make was that for non-fuzzy rules there are a lot 
of languages in use which people seem to want to exchange rules between, so 
I can believe that it makes sense to develop an interlingua now. Whereas 
it's not so clear that there are so many fuzzy rule languages that 
fuzzy-rule exchange is currently the presssing issue. It seemed more like 
the uncertainty use cases were asking for *a* solution rather than a way 
for their many solutions to interoperate.

 >>[der]
>>The stated requirement to "generalize the two-valued Boolean logic of
>>{0,1} into the interval [0,1]" seemed somewhat directed towards a fuzzy
>>logic solution.
> 
> 
> [Giorgos Stamou] 
> If it is because of the "[0,1]" requirement we could change it, although
> fuzzy logic will also follow it (other relevant theories would not).
> However, I think "[0,1]" is more preferable since it is a reasonable
> extension of {0,1}. 

The "[0,1]" bit is part of it.

In addition, the use cases presented seemed like they might be amenable to 
statistical techniques and were in domains where, IMHO, a precise 
understanding of the probability of an incorrect recognition is mandatory. 
It's not clear that all such statistical procedures can be thought of as 
generalizations of boolean logic.

> I understand that some language extensions will not be included and I
> respect your opinion that there is no clear need for the uncertainty
> extension to be included from the beginning (although if I correctly
> understand you are positive to be included in the future). I also recognize
> the very difficult and critical work of people writing the charter in order
> to fairly balance it between several other people needs and wants.
> But let me insist that it is fair enough to include the issue of
> uncertainty, which was mentioned a lot by industrial participants in the
> Workshop (which was organized mainly in order to find the industry
> requirements), nobody is really against it, and does not change the work of
> anybody.

Fair enough, I think I've expressed my reservations sufficiently and will 
shut up now.

Dave
Received on Monday, 12 September 2005 12:36:29 GMT

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