Re: Why not import everything? (was: Re: getting daml:importsright is easy?)

Jim Hendler wrote:
> 
<snip>
> 
> Now, on the inferencing end, a few things could happen --
>   i. we could insist this student has to understand all the info in
> CYC and agree to it (i.e. by using imports correctly)
>   ii. we could automatically import all of cyc (and the others)
>   iii. we can figure out some way to "import" only the cyc#dog facts
> or otherwise say when you use a URI from an ontology it only
> "commits" to some localized stuff (perhaps only the exact subgraph
> you point to)
> 
> In the first case, the SW doesn't work because no way in heck is
> someone going to learn to commit to something like CYC by studying
> the whole thing and making sure it is consistent with her beliefs
> (imagine asking a naive user who wants to tell us about a dog that we
> need to go through a short little 40,000 step dialog to make sure she
> really understands what a dog is!)

First of all, I think the problem with the Cyc ontology is it is too
big. Semantic Web ontologies should be small and modularized.

Second, in order to avoid making every user learn logic and study every
ontology, I envision "ontology certification authorities." These
organizations will consist of logicians who make sure that an ontology
is correct, summarize it and give it a seal of approval. Users can then
freely pick and choose these ontologies with some confidence that they
will behave as they expect. Note, users are still free to create their
own ontologies and to use uncertified ontologies. Anyway, I think a
variation of this solution is viable.

> In the second case, the SW doesn't work because every inferencer will
> have to load the transitive closure of all the imported stuff - cyc
> alone is big enough to break most chainers, and this student also was
> linked to things in at least 5 other ontologies - and other students
> linked to hers.   Inference will grind to a halt when the transitive
> closure of "imports" is the entire semantics of the web - we're
> already talking millions of assertions on daml marked up pages (and
> that's mostly ontologies, not the instances)

I agree that this is an unworkable solution.

> In the third case, the user is happy, the algorithm designer is happy
> (with respect to scale), but the logician is unhappy -- this student
> is pointing at things which might be inconsistent!!!  Oh, the horror!
> 
> So my suggestion, learn to live with it!!   If you cannot work in the
> real world of messy data and inconsistent semantics, then get the
> hell off the web.

The problem is that there is more than just inconsistent semantics at
stake here. There is the whole trust issue. Now trust is something that
most proponents of the Semantic Web (including myself) say "we'll get to
later." But if we want to get this thing off the ground, we're going to
need an intermediate solution. Otherwise, the hackers and terrorists
will find the Semantic Web ripe for the picking. They won't need to
express contradictions, they can just ensure that there are so many
false axioms that you can't trust anything that's concluded by the
Semantic Web. I think imports is just the thing to handle this. With
imports, you can make an explict trust statement! When you import a
document, you say, "I trust this document" and reasoner that trust you
can reasonably trust that document as well. I think imports is as
cruicial to the Semantic Web as hyperlinks are to the the original Web.

> What can we do?  Let's get some folks thinking about a modern view of
> inference and ontology where the whole (semantic) world is one huge
> interlinked ontology (as the whole web is one huge interlinked
> document) and figure out how to live with it - because if we can't,
> this whole enterprise is doomed from the start to be no more
> successful than current AI systems.

I think this definitely a useful research direction, but I don't want to
rely on it as the only solution. Even if this sort of solution is
possible, I think it will take many years (or decades) to work it out,
and I don't think the world can wait that long for the Semantic Web.

Jeff

Received on Thursday, 23 May 2002 11:12:04 UTC