Re: modelling issue?

Hay Martin!

thanks for reply, with v clear examples

>
>
> I think this discussion can be kept pretty short:
>

We can (try to) keep the discussion short, but we may  not resolve the issue
unless we are prepared to go the bottom of
things. (however tedious that may be, grab a long drink)

 And I dont think we should exclude a priori that some of the issues being
raise if superficially addressed
are not at the root of the problems that come up elsewhere (using the 80:20
rule, the majority of the problems are caused by a minority of issues)


In OWL (and RDFS), domain and range specifications work different from what
> you would expect in a database world.
>

yes, I dont have a problem with that,

I would also add, that the core relational database principles apply to any
data model (not only to  a non database world)
 such as : referential integrity


>

>
> than a reasoner would infer that JohnLennon is a bird.
>

oopps,  and probably even more serious wrong inferences than that ..


> . But you still don't know whether the disjointness axiom or the property
> usage is incorrect.
>

And so? what would that result in? .....

I agree our systems should be able to handle uncertainty, and I am sure
ambiguity has its merits but...
lack of referential integrity cannot be overlooked even in the open world...

I am reading this, which contains related discussions

Ref: http://eprints.ecs.soton.ac.uk/6649/
 Managing Reference: Ensuring Referential Integrity of Ontologies for the
Semantic Web

Alani, H., Dasmahapatra, S., Gibbins, N., Glaser, H., Harris, S., Kalfoglou,
Y., O'Hara, K. and Shadbolt, N. (2002) Managing Reference: Ensuring
Referential Integrity of Ontologies for the Semantic Web. In: *13th
International Conference on Knowledge Engineering and Knowledge Management
(EKAW'02)*, Sigenza, Spain.


also I dont see how what you discuss resolves the problem of having RDF used
to represent different constructs

class:relation:class
 but also
class:attribute:value



but I admit I do not have the time (nor the competence) to work on this
myself, however from where I stand
I see some potential conflict and unreliability -

do you want me to be able to trust and rely on the open semantic web, or
not?


If I am right, a lot of  RDF data that is being triplified and populates the
web to support all the lovely LOD bubbles,
are indeed taken by RDFizing data contained in dbases, in fact, often by
simplying pushing a button 'make RDF'
The data in dbases tends to be modelled according to relational principles,
thefore referential integrity is inherent
and thats when SPARQL queries can work a beauty,  minus that, and all we are
left with is 'possibilties'

I sure have nothing against that  :-)

But please do correct me further, I am relatively new to this


P







>
> Thanks Dan and Lin
>
>
>
>  Domain and range are characteristics of properties (aka
> relationships, attributes), rather than of the things those properties
> relate to. And yes, they're not mandatory, you can declare and use a
> property without saying anything
> about it's domain or range.
>
>
>
>  Okay, in another, offlist reply, among other comments I receve the following
> statement
>
> Most books I have read state that you should be cautious about making domain
>
>
>  and range statements about properties.  The results, the books claim, are
> difficult to predict in large ontologies.
>
>
>
>  I seem to get two contradictory statements there (and it would not be the
> first time, argh - I get different people telling me different things about
> this), and not sure how to interpret them in relation to each other
> sorry if it's me actually missing out something
>
>
>
>
>   RDF expresses everything in terms of triples. Sometimes the triple is
> a relationship between a thing and another thing (which is often but
> not always named with a URI). And sometimes the triple is a
> relationship between a thing and a string (possibly language-tagged or
> data-typed). RDF actually calls the link in both cases a "property",
> but sometimes for communicating in other contexts you'll here
> "relation" or "relationship" (typically when the link isn't to a
> literal string value). And sometimes you will hear "attribute",
> usually when the value is a string literal.
>
>
>
>  okay, in the modelling world,  that would be regarded as something to be
> worried about,
> we call these 'conflicts'
> when one thing can be interpreted in more than one way, the system is likely
> to be brittle
>
>
>
>
>
>  We had an army of logicians and mathematicians go over the 2004 specs
> in great detail. They may have missed something, but I suspect our
> main difficulties are elsewhere...
>
>
>
>  well, maybe  a systems engineering perspective would provide additional
> views, or a system of systems engineering (as in network of networks),
>
>
>
>
>
>
>  Are the above points addressed in some RDF tutorial
>
>
>  Did you see http://www.w3.org/TR/rdf-primer/ ?
>
> yes s its a great reference document, but it s very long to read it word by
>
>
>  word, and there is no indication that it contains
> the answers I am looking for
>
> Lin,
> Jim H book is something that I want to get my hands on too, surely, still
> questions may have to be answered to issues
> that are not directly or explicitly addressed in the literature, I havent
> been able to set aside time to read it, but I ll try to accsss those chaps
> straight away
>
> P
>
>
>
>
> --
> --------------------------------------------------------------
> martin hepp
> e-business & web science research group
> universitaet der bundeswehr muenchen
>
> e-mail:  mhepp@computer.org
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