Re: Multiple Semantic Web Languages

From: Peter F. Patel-Schneider (
Date: 02/12/04

  • Next message: Ian Horrocks: "Re: Multiple Semantic Web Languages (was: Re: reifying variables)"
    From: Sandro Hawke <>
    Subject: Multiple Semantic Web Languages (was: Re: reifying variables)
    Date: Thu, 12 Feb 2004 11:43:21 -0500
    > > I argued long and loud in the W3C WebOnt working group about problems that
    > > using the RDF syntax caused.  This argument didn't go anywhere, so I gave
    > > in and created a partial solution for OWL. 
    > Do you remember why the WG disagreed with you?
    Because all Semantic Web langauges have to be same-syntax extensions of RDF.
    > > > I've
    > > > sometimes campaigned unsuccessfully for a standard meta-language, in
    > > > which the syntax and semantics of practical data languages are
    > > > described.
    > > 
    > > XML might be the syntax half of this.  Isn't model theory (or even
    > > mathematics) the semantics half?  :-)
    > Ah, I meant a machine-usable meta-language.  Like java byte code,
    > XSLT, or prolog DCGs -- something you can use to define a new language
    > such that computers can simply use the new language without human
    > assistance.
    Well, XML still works for the syntax side.  I don't think that you are
    going to have much luck on the semantics side.  
    > > > In any case, using an "RDF-Like" syntax is using counterfeit money and
    > > > I suspect is only accepted as the price of admission by mistake.  I
    > > > apologize for not noticing and commenting on SWRL doing this back in
    > > > November.
    > > 
    > > There have been several proposals to make this sort of solution the
    > > official one, including things like dark triples.
    > "Dark triples" was proposed during a time when RDF Semantics were
    > rather up in the air, I think.    It's less in-order now.
    No.  Dark triples were proposed when the RDF Semantics was pretty much
    determined.  They were always a way of escaping from the semantics.
    > > I would very much welcome a statement from W3C that Semantic
    > > Web languages do not have to be written in triples (or quads, or quints,
    > > ..., as in several recent proposals).
    > The consortium doesn't have many ways to make statements like that.
    Then what is Architecture of the World Wide Web, First Edition
    ( supposed to be?
    > Maybe the closest would be in the charter of a new working group or
    > activity.   In fact, the SWRL WG charter I floated a few months ago
    > had some words about the extent to which the language needed to be
    > based on RDF.
    > What I had in mind were rules like in n3, of the form
    >      forall u1, u2, ...
    >         { rdf graph }
    >         =>
    >         exists e1, e2, ...
    >           { rdf graph }      
    > where the rule itself did NOT have to be conveyed in RDF.  (I want
    > them to viewable as RDF, and I believe it's possible, but we didn't
    > want the WG to be forced to do that.)
    > I was interested in seeing if the rule language would itself turn out
    > to be a better RDF serialization language.   
    > Had this been given to the membership, and had the membership approved
    > it, I suppose you would have had much of what you want.
    > In more general terms, I think what qualifies or does not qualify as a
    > Semantic Web language is a complex social question.  What TimBL says
    > in speaches probably counts for a lot, what the consortium members say
    > in WG charters counts for a lot, but so does ... everything else.
    > And cool, useful, deployed, working systems speak very, very loudly.
    > > > You would agree there's a cost to each new language, right?  
    > > 
    > > No.  I do not believe that there is a net cost for most new
    > > languages/representations.  New languages/representations are accepted in
    > > part because of problems with existing languages/representations.  If the
    > > new language/representation does not have benefits outweighing its costs,
    > > it is unlikely to be accepted.
    > You changed "cost" to "net cost".  Big difference.
    Well, I would argue that even the gross cost is quite low, and in fact, may
    indeed be negative, particularly if the new language replaces an ugly botch
    (read RDF/XML here).
    > You're right about net cost; I was thinking about up-front costs or
    > barriers to entry.  Every new language that agents (eg browsers) need
    > to know makes the cost of developing a new agent higher.  But you're
    > right that the market will decide and people will implement at least
    > dozens of languages if the benefit is there.  And plugins help a bit.
    > Part of the role of the W3C is to try to cut down the number of
    > languages -- one scalable vector graphics language instead of four --
    > to keep this up-front cost in check.    This is something software
    > vendors and user communities really want.
    > There are also costs to users of upgrading their software, and costs
    > to developers of learning to use a new language.   There are great
    > network effects when more and more people use the same language.
    > Bookstores can label the shelf, instead of just having to hide the
    > books on each little language in Miscellaneous/Oversize.  
    > So I'm all for people competing with RDF/XML in the hopes they come up
    > with something really better, but we should recognize that it's mostly
    > a winner-take-all proposition, and we can't expect to let a thousand
    > Semantic Web languages bloom (except via the meta-language approach,
    > perhaps).
    > All of this is perhaps irrelevant to the original "reification of
    > variables" question, since a logic language with its syntax encoded in
    > RDF can hardly be said to be itself RDF.  It is its own language, with
    > its own deployment and cost issues, even if carried on RDF/XML.  All I
    > was saying was that IF you're going to encode the syntax for the
    > language in RDF, for whatever reason, please encode it in real RDF
    > (with real RDF semantics [plus iron]), not in an RDF-like language
    > with insidious differences from the standard.
    Well, the problem, as I see it, is that RDF encoding is mandated, but RDF
    embedding is impossible, so the only solution is the solution embodied in
    >   -- sandro

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