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AW: [ontolog-forum] Current Semantic Web Layer Cake

From: Valentin Zacharias <Zacharias@fzi.de>
Date: Thu, 2 Aug 2007 22:14:26 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A02C342D@judith.fzi.de>
To: "Pat Hayes" <phayes@ihmc.us>, "John F. Sowa" <sowa@bestweb.net>
Cc: "[ontolog-forum]" <ontolog-forum@ontolog.cim3.net>, "Ivan Herman" <ivan@w3.org>, "Juan Sequeda" <juanfederico@gmail.com>, "SW-forum list" <semantic-web@w3.org>


Pat Hayes said:
>I am slightly concerned that this peculiar kink in the layer 
>cake has been put there deliberately to make it possible to do an 
>end-run around a unifying logic. Which when one takes into account 
>the whole point of "Unifying", would IMO be a pity.

I can understand that people insist on Semantic Web languages to have a
formal, or even a model theoretic semantic. What I don't get is that you
(and John F. Sowa in other emails) seem to insist that this must be classic,
FOL like, monotonic semantic and that all formalisms with different
semantics (or kinds of reasonings) have no place in the Semantic Web. 

To me it seems obvious that these semantics cannot be the exclusive basis
for reasoning on a global,open knowledge based system, because:
1) These semantics do not consider quantitative aspects (e.g. 5000 locations
state that a(mike), only 2 state that b(mike)), don't allow for closed world
reasoning, do not consider trust, require very strict global consistency....
Because of this they cannot reflect the intuitions and expectations of
humans about what should be concluded from a set of statements as unordered
and ungoverned as the web.  Hence actual applications will in any case use
other notions of truth and entailment (or come to conclusions that are not
accepted by the users and probably not very useful).* 

2) Should we really ever get reasoning semantic web agents, isn't it
preposterous to assume that will rely exclusively on logical deduction?- Why
not induction, abduction, analog reasoning, data mining, nlp, ir, simulation
... Doesn't this mean that in any case there will never be a complete
mapping between the "proof" and the "logic" layer (as currently envisioned)?
I also don't see how any kind of inference can be done on web scale without
a large (essentially heuristic) information retrieval component trying to
get the relevant statements (considering what we know about the complexity
of inference algorithms) - again breaking the direct logic layer-proof layer

my opinion in short: we don't have any semantics that covers everything that
is needed (and I don't even see one at the horizon), hence we should not
stifle innovation by insisting on one thats clearly inadequate for the task
at hand. 



*: given the large amount of research into things like circumscription,
uncertainty reasoning, rdf/dl+contexts etc. I was under the impression that
this is a SW-community mainstream position. 

email: zacharias@fzi.de
phone: +49-721-9654-806
fax  : +49-721-9654-807

FZI  Forschungszentrum Informatik an der Universität Karlsruhe (TH)
Haid-und-Neu-Str. 10-14, 76131 Deutschland, http://www.fzi.de
SdbR, Az: 14-0563.1 Regierungspräsidium Karlsruhe
Vorstand: Rüdiger Dillmann, Michael Flor, Jivka Ovtcharova, Rudi Studer
Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus

> -----Ursprüngliche Nachricht-----
> Von: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org]
> Im Auftrag von Pat Hayes
> Gesendet: Dienstag, 31. Juli 2007 17:20
> An: John F. Sowa
> Cc: [ontolog-forum]; Ivan Herman; Juan Sequeda; SW-forum list;
> semantic_web@googlegroups.com
> Betreff: Re: [ontolog-forum] Current Semantic Web Layer Cake
> >Pat,
> >
> >I agree that the proof box is misplaced, but I think
> >that the major problem is that the logic box is not
> >correctly positioned.
> >
> >>  http://www.w3.org/2007/03/layerCake.png
> >
> >PH> Hmm, I wonder why the 'Proof' Tetris piece has
> >>  a connection to Rule without going through Unifying
> >>  Logic.  That seems like a very bad decision to me
> >
> >Unifying Logic is the framework that includes the others
> >as subsets:  RDF, RDF-S, Rule RIF, OWL, and SPARQL.
> >
> >Each of these subsets is tailored for a specific kind of
> >inference engine and/or a specific range of uses.  What
> >unifies them is the common model-theoretic semantics.
> >That semantics enables all of them to interoperate on
> >shared data and produce consistent results.
> Thats what I would expect, yes. And I know the overall picture. What
> surprised me was the fact that there seems to be a special
> short-circuit allowing Rules to connect to Proof without taking the
> Logic into account. Which in turn suggests a special dispensation for
> Rules to avoid having to have a common semantics with everything
> else. As I know there are, as the popular media says, Powerful Forces
> in the Rules meta-community which would approve of short-circuiting
> conventional semantics altogether in favor of, say, some version of
> Prolog, I am slightly concerned that this peculiar kink in the layer
> cake has been put there deliberately to make it possible to do an
> end-run around a unifying logic. Which when one takes into account
> the whole point of "Unifying", would IMO be a pity.
> Pat
> >
> >My suggestion would be to draw the Unifying Logic box as
> >a large container that includes all the others inside:
> >RDF, RDF-S, Rule RIF, OWL, and SPARQL.
> The layer-cake display has become a kind of W3C icon now.
> --
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Received on Thursday, 2 August 2007 20:15:16 GMT

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