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Re: [ontolog-forum] Current Semantic Web Layer Cake

To: kuldar@xxxxxxxxxxxxxxxxxxx
Cc: Valentin Zacharias <Zacharias@xxxxxx>, "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>, Juan Sequeda <juanfederico@xxxxxxxxx>, SW-forum list <semantic-web@xxxxxx>
From: "Danny Ayers" <danny.ayers@xxxxxxxxx>
Date: Sat, 4 Aug 2007 18:05:57 +0100
Message-id: <1f2ed5cd0708041005w142c4f1etc6d627d9d70f92de@xxxxxxxxxxxxxx>
On 04/08/07, Kuldar Taveter <kuldar@xxxxxxxxxxxxxxxxxxx> wrote:    (01)

>  I must say that I totally agree with Valentin. It is not possible to solve
> the interoperability problem by imposing
>  a set of standards "from above". The world is too diverse a place to assume
> that everyone is going to use them.    (02)

Hmm, I generally agree with the "from above" point, yet I find myself
disagreeing quite strongly with Valentin...    (03)

It does seem to be reasonable to try and build a global data system
based on what we've already got with the Web. So what might be the
simplest and most flexible approach?    (04)

The Web essentially consists of documents and links (enabled by HTML
and HTTP). A link is a relationship between the current document and
another document. There's a familiar data model here, if you
generalise from documents to arbitrary entities, and give the
relationships types. This is very much in reach of contemporary
software practice: entity-relationship style data has echoes in
object-oriented programming and can be mapped to Codd style relations.
Conveniently it also maps to some of the logical predicates  of FOL.    (05)

Documents are named uniformly with URIs, so it makes sense to name the
entities and relationships of this extended Web following the same
system.    (06)

One advantage of the Web over other approaches to hypermedia is that
it takes into consideration the broken link, the missing document -
the 404 Not Found is very much a feature, not a bug. In the data model
scenario, there's a reasonable analogy with the open world assumption.
Allow for unknowns.    (07)

...and there in a nutshell you have most of RDF, the core of the
Semantic Web technologies.    (08)

(Ok, a lot of logician-hours and practice went into producing the
current specifications which allow this naive post hoc derivation, but
I reckon it's still valid).    (09)

There may be arguments what's best to layer on top of this system, and
it's interesting to note that certain aspects of RDF that go beyond
these basic components (bnodes, RDF reification) are actively avoided
by some (er, increasingly many) implementors.    (010)

But this foundation is very much capable of supporting a whole range
of alternatives whilst maintaining Web-style compatibility. It's
already demonstrating utility, based on tools ranging from
data(/abstract syntax)-oriented query setups to more formal
DL-oriented reasoning systems.    (011)

Re. "The world is too diverse a place to assume that everyone is going
to use them."    (012)

What of HTML and HTTP?    (013)

Danny.    (014)

--     (015)

http://dannyayers.com    (016)

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