W3C home > Mailing lists > Public > www-rdf-logic@w3.org > April 2001

Re: A plea for peace. was: RE: DAML+OIL (March 2001) released: a correction

From: pat hayes <phayes@ai.uwf.edu>
Date: Tue, 3 Apr 2001 09:42:09 -0700
Message-Id: <v04210107b6ee749a9290@[]>
To: "Jonathan Borden" <jborden@mediaone.net>
Cc: <www-rdf-logic@w3.org>
>Jim Hendler wrote:
> > >RDF needs to be integrated with the XML datatypes.  Shall I take it
> > >that DAML+OIL isn't going to help out on this?
> > >
> >
> > Jonas asks a good question - let me try to help out as best I can
> >
> > DAML+OIL did not have authority to change anything in RDF or to
> > otherwise impact the RDF spec except by example.  We decided to take
> > on the datatyping issue because it was important to our users.
>	DAML+OIL is in an interesting position due to the nature of 
>its editorial
>board, and I imagine is in a strong position to impact RDF - hopefully in a
>good way. Let me say that I believe the attitude of trying to pitch in and
>arrive at solutions to problems is a highly constructive one.
>	It has been distressing to me to see some of the DAML+OIL group bluntly
>proclaim that RDF is ultimately a bad way to do xxx or yyy, with the strong
>suggestion that the only reason they are working with RDF is as if someone
>is actually holding a gun to their heads.

Well, not a gun; but you have the right idea. I might put on record 
my negative reaction to RDF since day one, long before DAML was 
proposed. Not to the goals or ambitions of the RDF effort, to which I 
am committed, but to the formalism itself. I protested to members of 
the RDF working group when RDF-1 was first released that it was 
irresponsible to put out such an inadequate model as a proposed 
standard, and was told that things would be improved in version 2. 
Instead, RDF-1 has become adopted as a de facto standard, essentially 
by inertia and political pressure.

There are few things more harmful to the world than bad standards 
which take root and then have to be grandfathered for eternity. DOS 
is a memorable example.

>	I think everyone agrees that there are some problems in 
>various areas of
>RDF. However I think that statements such as:
>"I strongly agree with Pat Hayes's characterization of RDF (and RDFS) as
>based on a fundamentally flawed semantic model."
>are not supported by practical suggestions as to what might be fixed. Such
>broad statements are not helpful, rather are merely inflamatory.

They should be taken to be simple technical claims. Peter has 
explained the technical problems succinctly and accurately. What more 
do you want?
The way to fix RDF is to admit that logical content requires the use 
of some - maybe not many, but some - nontrivial syntactic 
constructions, in particular the use of nested expressions and 
quantifier scoping; to abandon the idea that syntax is the same as, 
or best coded using, reification; and to make a committment to 
precision in specifying logical meanings (which might include being 
precise about what one is NOT saying, by the way: precision doesnt 
entail being exhaustive.) The tools for doing this have been 
available for more than half a century and are about as thoroughly 
understood as any part of modern mathematical practice can possibly 
be. Once one uses the proper tools, it is much easier to do good 
work; in fact, the tools often do a large part of ones thinking 

>Indeed I
>could easily state that _no model anywhere_ I've ever seen is anything other
>than semantically flawed.

In the sense that Peter and I are referring to, this is simply false. 
There are *many* models which do not have these very basic flaws. 
Prolog does not have these flaws. Most industrial-grade data models, 
such as EPISTLE, do not have them. CLASSIC, LOOM and OIL do not have 
them. KIF does not have them. Even FORTRAN doesn't have them.

>Such discussions have no end, occur frequently,
>and have little impact.

I suspect that you have not understood what Peter and I were talking about.

Perhaps I should explain the source of my exasperation. These issues 
that we are referring to are not really very deep or subtle points, 
and they are not mere debating points, and they are not philosophical 
stances on the nature of true meaning. They are technical flaws which 
are vividly and immediately obvious to anyone with a basic technical 
education in the relevant subject-areas.

>To make such a characterization simply negates the
>usefulness of "semantic" as a term of discourse.

The term "semantic" in the sense Peter and I are using it has a 
precise mathematical meaning.

Part of the problem, I suspect, is that many people seem to think 
that questions broadly concerned with meaning, semantics and 
representation are somehow off-limits for technical discussions, or 
can only be approached through literary criticism. Nothing could be 
further from the truth. The RDF community seems to be imbued with a 
whiff of Derridian postmodernism, which it needs to wash off 
thoroughly before we can make progress.

>Perhaps we should simply
>agree not to use this word, nor the term equally ambiguous term "knowledge"

I agree that this particular word has its dangers, though in the 
context of the expression "knowledge representation" it has a 
reasonably crisp technical meaning, and the philosophical hinterland 
which surrounds it has been extensively explored.

>and define our shared goals in a more practical fashion e.g. "design an

"Agent" is a real horror-word.  It has at least five distinct 
meanings even in the recent "technical" agent literature, none of 
them exact. (1. Roaming chunk of software; a web-crawler. 2. Piece of 
software with a humanoid GUI, typically a face which attempts to 
represent emotional states. Sometimes used for entire robots, cf. 
MIT's 'COG'. 3. Piece of software which acts autonomously while 
'representing' its user's goals, or claiming its users rights, in 
some social sense. 4. Simulated social agent in a virtual or 
semi-virtual 'world'; a Sim.  5. (Colloq.) Any piece of software 
claimed to be 'intelligent' but which its author does not want to 
characterise as "AI". Typically, the software has no measurable 
intellectual capabilities. ) My own personal, slightly 
tongue-in-cheek, definition is: anything with which one communicates 
using an exchange protocol.

>that has the following characteristics ... and is able to successfully
>complete the following tasks ..."

The trouble is that these specs are likely to use words that 
ultimately can only be properly defined by reference to a semantics. 
(eg "correct", "inference", "valid", "truth")

> > Unlike Pat and
> > some others, I do think RDF compatibility is a crucial aspect of the
> > DAML languages, and to this end I have agreed to work with the W3C to
> > help in whatever way I can to coordinate ontology efforts with other
> > RDF efforts.
>I think that the essential characteristic is perhaps not RDF compatibility
>(as RDF exists today) rather integration with the distributed Web
>architecture and that means that URIs are the heart of the real issue.

I wholeheartedly agree with you there. The only *logical* things that 
are particularly new about 'web logic' are all issues that arise from 
name scoping. However, I think that the distributed web architecture 
does raise other issues which an 'agent' [sound of teeth grating] 
needs to be sensitive to, chiefly concerned with issues of 
intertranslation, reconciling conflicts, and reasoning about trust 
and authority.

>think that whether the RDF model is triples or quads or foo is a side issue,
>the real issues that need to be solved are:
>1) imprecise perceptions about what URIs and resources are to begin with.
>RFC 2396 is broad in its definitions and we might take this opportunity to
>introduce more structure into the definitions of URI, URI reference,
>resource, entity etc.

I would welcome that. I am still trying to discover what a URI is 
beyond simply a URL. I suspect that it is to some extent an kind of 
W3 dream: a vision of a future where everything is on the Web and 
everything has a single True Name which all beings will recognize. I 
don't believe this will ever happen, for various reasons, but I would 
like to see these matters discussed, as I think it is important to 
get everyone's assumptions (social, semiotic, philosophical, 
political and technical) out into the open.

>2) integration of RDF with other web standards in particular XML. Alot has
>changed in the XML world since the RDF recommendation came out. XML has
>gained wide adoption across industry, academia and plain ol' web hackers
>(this last one perhaps to a less wide extent). If DAML+OIL is struggling
>with whether to maintain RDF compatibility or not, the issues regarding
>integration with XML and specifications such as XML Schema would appear
> > If a working group is formed to attack the remaining
> > issues of RDF (which might include the datatypes) I suspect that I
> > and others on the US/EU committee would be happy to join and work on
> > finding a clean solution.
>Working together is in everyone's best interest. A strong core RDF standard
>is good for RDF and for everyone who uses RDF.

I'm tempted to ask about those who DONT use RDF, but I guess this 
would be impolitic; so in the interests of collegiality I will 

Just for clarification, my diatribes against RDF are not in any way 
intended to be directed at XML.

> >[Jim Hendler:]
> > That said, as long as we maintain syntactic compatibility, it's not
> > clear to me that the higher levels of the diagram alluded to above
> > can never have their own way of doing things.

Well, let me temper your enthusiasm here. As one of the original 
troublemakers on this thread (bundle?) , I also entirely agree with 
what Jim says here. But notice that he refers to *syntactic* 
compatibility, while Peter and I were grousing about RDF as a 
*semantic* model. Different issues.

>.... The only way
>this is all going to work is if it works on the Web, the non Web experiment
>has already been tried.

Could you expand on that interesting observation?

Pat Hayes

IHMC					(850)434 8903   home
40 South Alcaniz St.			(850)202 4416   office
Pensacola,  FL 32501			(850)202 4440   fax
Received on Tuesday, 3 April 2001 13:53:38 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 2 March 2016 11:10:34 UTC