[topicmaps-comment] Fwd: CG: Re: REQUEST: survey of availableontologies...

[Jack Park <jackpark@thinkalong.com>]

These comments by John Sowa from the CG list may be of interest to some 
readers.
Cheers
Jack


>From: "John F. Sowa" <sowa@bestweb.net>
>Reply-To: cg@cs.uah.edu
>
>Folks,
>
>In the interests of reducing the volume, I'll combine my comments to
>several of the postings into one note.  Unfortunately, many of those
>postings came from different lists, so I'm doing some cross-posting.
>I promise that this is my last reply to this thread.
>
>Frank van Harmelen wrote:
>
> > I guess you refer to diagrams such as [1].
>
> > This is only meant to convey that RDF is the syntactic carrier for
> > ontology languages and other logical formalisms (and XML is in turn
> > the syntactic carrier for RDF).
>
> > I don't think it was ever meant to imply that logic-based analysis
> > of a domain would not be needed before using RDF/RDF Schema as a
> > notation.
>
> > The picture is only a rather matter-of-fact statement about the
> > technical infrastructure for the Semantic Web, not a deep
> > methodological issue.
>
>I agree that is one interpretation.  But I also recall a talk by
>Eric Miller, in which he commented that the layers get less well
>defined as you go up.  That annoys people like me who believe
>that classical FOL is the best defined of all notations on earth.
>
>I think that any layer-cake diagram would be misleading in some way,
>since logic is needed at the lowest level to define all the other
>notations, and it is also needed at the level of tools that do
>reasoning -- deduction, induction, and abduction.
>
>David Sallach wrote:
>
> > Are 1) logic and 2) ontology as separable as the above subdivision
> > suggests?  That is, while I agree that formal structure and rules of
> > inference are highly desirable, it is less clear that logic itself
> > has reached a final, stable form.  Rather, while better defined than
> > ontology, logic may still be evolving as well and, in fact, may
> > coevolve with putative ontologies, in which case, the initial
> > subdivision may be misleading.
>
>I admit that any definition that is simple enough to be understandable
>must leave out many qualifications that could make it misleading.
>Later in the book, I qualify the distinctions by listing the
>characteristics of various notations that are called logics, and
>note that many of them, especially variants of temporal logics,
>really incorporate major ontological assumptions.
>
> > The particular initiative I have in mind is situation theory (and
> > related frameworks such as relevant logic and dynamic logic).  Because
> > natural language is one of the primary domains of situation theory,
> > it addresses many of the issues discusssed in the Program Semantics
> > thread.  However, it also attempts to extend predicate calculus by
> > adding existential as well as syntactic assertions and constraints.
>
>I agree that those formalisms mix ontological assumptions with the
>logical formalism.  I also mention music notation in Ch. 1 of the book
>as a classic example of a notation that mixes a simple version of logic
>(with only conjunction and an implicit existential quantifier) with
>an ontology for sequence, duration, pitch, loudness, and concurrency.
>Such mixtures are very useful for many purposes, but I believe we
>should determine exactly where the logic stops and the ontology begins.
>
> > We cannot yet know the ultimate contributions of these movements,
> > but is it not possible that some vexing problems may be addressed
> > most effectively by the emergence of novel ontologies combined with
> > innovative formalisms?
>
>I am happy to endorse work on the development of novel notations that
>mix logic and ontology in any way that the designers believe is useful.
>And again I would cite music notation as an excellent example of the
>genre.  But I believe that the resulting mixture should not be called
>a "logic", but rather a language or notation that explicitly mixes
>logic and ontology.
>
>Bill Andersen wrote:
>
> > There are several relatively weak representation formalisms out there
> > that are being touted as suitable for building "ontologies", most
> > notably in the WWW/W3C communities.  XML/S is only one of those often
> > heard of in this connection.  The claim that they are sufficient for
> > ontology is implicit in the advertisement of this or that project,
> > written in these formalisms, as "ontology".
>
>As I said before, I have no quarrel with people who design a notation
>that may combine a limited logic with a special purpose ontology.
>Music notation is an example, but no one claims that music notation
>can solve more general problems of ontology.
>
> > These languages *are* logics of a sort.  Worse yet is that they pack
> > in all kinds of implicit philosophical assumptions that, in the
> > hundreds of pages of detailed specifications that come with these
> > beasts, get lost in the noise.  Nobody (probably even the language
> > designers) know they are there.
>
>I agree.
>
> > But they (the philosophical assumptions) have real impact.
> > Necessarily existing properties?  No problem: OIL (or any DL) has 'em!
> > No theory of identity?  No problem: different name -> different
> > object!   Relational properties (e.g. "Italian")?  No problem: they
> > don't exist because they cause computational problems.
> >
> > As a friend of mine always says, let's not confuse activity with
> > progress.
>
>To paraphrase Socrates, "An unexamined notation is not worth writing."
>
>Jim Hendler wrote:
>
> > ...while this is true, it doesn't mean the logic must be explicit
> > in the language, just that their must be a formal model underlying
> > the language...
>
>I agree.  But I believe the designers of the language should pay more
>attention to these issues, instead of throwing the language over the
>wall and hoping that somebody like Pat Hayes will catch them, clean
>them up, and give them the good logic stamp of approval.
>
> > ... But John, you yourself know that there is a clear difference
> > between the encoding and the logic - so how can you make such a
> > ridiculous claim.  Of course there must be an underlying logic -- but
> > that logic doesn't need to be expressible on the web to be useful --
> > the underlying logic below DAML+OIL, for example, can be expressed in
> > KIF (see the axiomatic semantics [1] ) or Model Theory (see the
> > semantic model [2])
>
>I know that and you know that.  But as Bill pointed out, there are
>so many different notations with different underlying logical and
>ontological assumptions that no one -- not their designers, their
>users, or their reviewers -- knows how each of them is related to
>each of the others.  Giving a model theoretic foundation for each
>notation can prove that each one is consistent by itself.  But it
>cannot show that using several of them together will be consistent,
>meaningful, or usable for any practical application.
>
>And your own reply to Bill illustrates the problem:
>
> > ...  When you write classical logic with all the usual symbols it is
> > meaningless scrawling on a piece of paper until we have the social
> > agreement about how the symbols map to mathematical concepts.
>
>I agree.  Now imagine a few billion web pages with hundreds of XML
>based languages scrawled across them.  Each one might have been well
>designed by itself, and all of them may be processed by a common set
>of XML tools.  But where is the social agreement that relates the XML
>tags of one notation with its implicit logic and ontology to the XML
>tags of another notation with a different set of implicit assumptions
>about logic and ontology?
>
>John Sowa
>
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