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Re: pruning the semantics document (and "meaningless terms")

From: Frank Manola <fmanola@mitre.org>
Date: Wed, 11 Dec 2002 16:25:59 -0500
Message-ID: <3DF7AD67.2020200@mitre.org>
To: pat hayes <phayes@ai.uwf.edu>
CC: w3c-rdfcore-wg@w3.org, Patrick Stickler <patrick.stickler@nokia.com>

Pat--

I'm sorry, but on the basis of Patrick's recently-expressed concerns 
about "meaningless terms", I've got to temporarily object to this.  The 
problem is roughly this:

When I said:
 >>All these terms are discussed in the Primer (in some cases extensively),
 >>together with examples of their use.  In all the use cases, there are
 >>caveats expressed that describe these as "intended meanings",
 >>
Patrick said:
 >
 > But intended by whom? If they are intended by the RDF Core WG, then
 > they should be normative. If they are intended by someone else, why
 > should we say anything about them or even include the terms in the
 > RDF vocabulary.

and later said:
 > Precisely. I think that the Primer should reflect, in minimally technical
 > and accessible terms the normative content of the other documents, and
 > the examples and verbage for these terms does in fact suggest that RDF
 > is asserting meaning for these terms which it is not.

So it seems to me that when the Semantics document describes the 
intended meaning of terms from this vocabulary, like containers and 
collections (and reification, and ...), it's a normative statement of 
our intent (even if we can't fully define the semantics formally), and 
it's OK then to elaborate on that in the Primer.

[NB:  The Semantics document I'm referring to is 
http://www.coginst.uwf.edu/~phayes/RDF_Semantics_finalCall.html]

If anyone thinks the above is a sneaky argument, consider also the 
following:

a.  Several applications described in Section 6 of the Primer use the 
container vocabulary, and it seems to me they use it correctly. 
Although we can't formally define everything about this vocabulary, it 
seems to me we've stated it well enough in English so people can use it 
with a reasonable degree of interoperability.  We could elaborate more 
on that in the Semantics document (describing it as "intended" again) if 
people insist on something normative.  But I don't understand how 
directing people away from that vocabulary, and forcing them to 
individually invent N different representations for containers on their 
own, helps achieve the goals of globally-consistent meaning.

b.  We added the "meaningless" collection vocabulary not that long ago. 
  This isn't a piece of bad old legacy syntax from M&S.  Did we really 
have no normatively-describable intent in doing that?  If so, then we 
can delete it now without impacing anyone can't we?  If we actually mean 
something by it (and I think we did), then let's say it.  (And I think 
the Semantics document *does* say it, and the Primer reflects that).

c.  There are some problematic aspects of the other vocabulary items, 
but not that many really.  rdfs:comment?  Say in some normative document 
that it's intended to provide a place to put comments (actually, I think 
Schema covers that, at least about our "intent", and also does so for 
the other terms mentioned in the following).  No one expects any more 
formal semantics than that for a comment anyway do they, and why not 
have a pre-defined way to make comments (most languages do)? 
rdfs:label?  Same comment.  rdfs:seeAlso?  Relatively harmless.  It says 
there'a relationship between the subject and object of the statement. 
Big deal.  That's exactly what the formal semantics are.  Users could 
define their own names for that relationship depending on how they use 
it, so we could delete it, but why bother.  rdfs:isDefinedBy?  It's a 
subproperty of rdfs:seeAlso.  Say what the intent is (which the Schema 
document does) and forget it.  rdf:value?  We've been working on that, 
but I don't think we've achieved closure yet.  (But there's a nice 
description of our intent in the Semantics document.)

So my current suggestion is to leave the current descriptions in the 
Semantics document, so they're "normative", and we can continue to talk 
about the uses of useful vocabulary in the Primer (of course, with 
appropriate caveats about what is *not* guaranteed about uses of these 
terms).

--Frank

pat hayes wrote:

> 
> After reading through the Primer, particularly section 4, I propose that 
> almost all of section 3 of the semantics document be simply removed. 
> It's all in the primer section 4.
> 
> Semantics section 3 should just list the RDF vocabulary that isn't being 
> given a formal meaning, say explicitly that it isn't, and refer to the 
> Primer for the informal meaning. If anyone feels that there are any 
> subtleties in section 3 that aren't in the primer text as it stands, 
> then lets put them into it. I don't think there are many, if any, in fact.
> 
> Anyone object? Frank??
> 
> Pat


-- 
Frank Manola                   The MITRE Corporation
202 Burlington Road, MS A345   Bedford, MA 01730-1420
mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875
Received on Wednesday, 11 December 2002 16:14:12 EST

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