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Re: [ontolog-forum] Model Semantics, Representation Syntax, and Systems

To: ontolog-forum@xxxxxxxxxxxxxxxx
From: Christopher Menzel <cmenzel@xxxxxxxx>
Date: Wed, 10 Nov 2010 18:12:11 -0600
Message-id: <4CDB34DB.9020203@xxxxxxxx>
Alan, thanks for the helpful and interesting post.  You wrote:    (01)

> On Wed, Nov 10, 2010 at 1:30 PM, Christopher Menzel<cmenzel@xxxxxxxx>
> wrote:
>> On Nov 10, 2010, at 12:16 PM, Alan Ruttenberg wrote:
>>> On Wed, Nov 10, 2010 at 10:14 AM, Kingsley Idehen
>>> <kidehen@xxxxxxxxxxxxxx>  wrote:
>>>> Alan / John: maybe we could use this thread to arrive at obvious
>>>> common ground re. data integration and the diminishing need for a
>>>> syntax level lingua franca.
>>> Kingsley includes me presumably because of a response to an earlier
>>> message, not copied to this list.
>>> http://lists.w3.org/Archives/Public/public-lod/2010Nov/0322.html
>>> I think there *is* a need for a lingua franca for intercomputer
>>> communication. But I support the idea that there should be
>>> alternative syntaxes (as long as they can be clearly translated to
>>> the lingua franca).
>> Well, that is pretty much exactly the idea behind Common Logic.  It
>> is a semantic framework that supports an unlimited number of
>> alternative languages -- although it does not privilege any
>> particular language (a.k.a., CL dialect) over any other (although the
>> KIF-like dialect CLIF is sort of a default).
> *Any* semantic framework (including OWL) supports an unlimited number
> of alternative languages (by language I assume you mean concrete
> syntax).    (02)

Well, there's alternatives and then there's alternatives. :-)  It is of
course true that, in most presentations of, say, first-order logic, the
semantical framework supports infinitely many different languages.  But
in most every case the languages differ only with regard to their
nonlogical signatures, not their general syntactic "style".  A semantic
framework that supports the usual contemporary syntactic style inherited
from Principia Mathematica, for example, is simply inapplicable to a
KIF-style, LISPish syntax or the 2-dimensional graphical syntax of
conceptual graphs.  Common Logic supports all of them.    (03)

> However, the effect of not privileging any particular syntax is that
> unless there are reliable translators between the different syntaxes
> there is an (uninteresting, but very real) barrier to integration. I
> haven't checked on CL, but IMO, it should have a normative syntax that
> is considered the one that projects should make sure they can produce,
> so as to remove the aforementioned barrier.    (04)

Agreed, but that is a social matter (an important one) that can be left
up to a given community, isn't it?  In point of fact, though, as noted,
the CLIF dialect, with its roots in KIF, seems to be the natural
candidate for that role.    (05)

> The main difference between OWL(DL) and CL (correct me if I am wrong)
> is that CL lets you say anything in FOL, while OWL let's you only say
> some things in FOL, and (at least one thing - property transitivity)
> that is in SOL.    (06)

If you are talking about OWL's abstract syntax (as I believe you are)
then, yes, OWL(DL) and CL are quite similar in providing frameworks that
allow for very different concrete languages.  However, OWL requires that
every concrete OWL language come stocked with a large number of logical
primitives (e.g., "Class", "restriction" "minCardinality", etc) and,
moreover, in the abstract syntax, requires them to take only one
particular form.  CL only requires the usual array of logical
connectives and, moreover, allows languages to express them however they
choose, e.g., universal quantification can be expressed with an
upside-down A, in the form (x), as "forall", or with a combination of
tokens and graphical relations as in conceptual graphs.  (Of course,
OWL's syntax *could* be made similarly abstract, so I don't take this to
be a particularly significant point of difference between CL and the
current manifestation of OWL.  I am only pointing out differences here,
not arguing for the superiority of one over the other (nor would I try
so to argue, as I think OWL and CL are largely designed with different
purposes in mind.)    (07)

> The main practical issue with using unrestricted CL is that there are
> few systems that can reason (in a predictable way) over it. One might
> consider it for communicating OWL, but then only some part of CL would
> be able to be used, and I don't know that authoring systems are such
> that they can helpful for users who want to do that.    (08)

Yes, when we get into reasoning issues, the connections between OWL and
CL grow murkier, since so much of OWL's development was driven by the
preservation of decidability and, well, basically none of CL's
development was (by design).    (09)

> A problem I see with all the normative languages is that they don't
> support much in the way of syntactic abstraction - macros. They would
> be much friendlier if they did, as then the formats themselves could
> carry around the necessary machinery to translate from alternative
> syntaxes to common syntax. I tried to advocate for that to be included
> in the OWL spec, but didn't succeed.    (010)

Too bad! :-)    (011)

-chris    (012)

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