Re: modelling issue?

Pat,

As I said earlier, going through various replies

(btw most of  the book is on googlebooks!)

*Semantic* web for the working ontologist: modeling in *RDF*, RDFS and OWL -
Google Books Result<http://www.google.co.uk/url?sa=t&source=web&ct=res&cd=3&url=http%3A%2F%2Fbooks.google.co.uk%2Fbooks%3Fid%3DRnFjZTfPILcC%26dq%3Dallemang%2Bhendler%2Bsemantic%2Brdf%26printsec%3Dfrontcover%26source%3Dbl%26ots%3DIAvsdgS2ir%26sig%3DxITBbfJ1Mbd2Dt8OEs66cT249CU%26hl%3Den%26ei%3D_NXISvLFI4G5jAe8_rU4%26sa%3DX%26oi%3Dbook_result%26ct%3Dresult%26resnum%3D3&ei=_NXISvLFI4G5jAe8_rU4&rct=j&q=allemang+hendler+semantic+rdf&usg=AFQjCNH6dnEq4FXrYM5FU9o9Eww19FJIAw&sig2=FnyN3fgH5u8ozbDbKI1CEg>by
Dean *Allemang*, James A. *Hendler* - 2008 - Computers - 330 pages
Semantic Web for the Working Ontologist transforms this information into the
practical knowledge that programmers and subject domain experts need.
books.google.co.uk/books?isbn=0123735564*...* -


I have come to the conclusions that although  there may be conceptual
modelling issues somewhere that I havent been able to put my finger on yet
(will work on it ), it's pretty clear that some additional ambiguity emerges
in the way the information is presented/discussed by different proponents
(when I first came across RDF it looked really straighforward, now that I
try to
work it it a bit less, and get different messages too)

I do get different answers, which in turn point to different issues, for
example the interesting recent discussion on extensionality and
intensionality that may be possibly overlapping some of what I am trying to
put my fingers on

http://www.semanticuniverse.com/blogs-intensional-and-extensional-sets.html
http://www.semanticuniverse.com/blogs-intensional-and-extensional-owl.html

Since you offer to districate, let me ask:

>
>>


>
> That is the full story on domains and ranges in RDFS (and in OWL, for that
> matter). So I'm not sure what you mean by the domain/range of an *entity*.
>

sorry that was just wrong, legacy of previous conversations


> BTW, there is no RDF requirement that domains and ranges be specified. You
> can just say nothing about them unless you want to.


I think here I was seeking for some guidance: is ther a rule/recommendation
for when I should, and when I shouldnt
or
is there a natural way of making the choice ? (rather than just leave it
blank where I am not sure, which does not see right)



>
>>
>> class:relation:class
>>
>>  but also
>> class:attribute:value
>>
>> Of this i would like some confirmtion (is this right?
>>
>
> No. Or at any rate, not if I am following you. First, the first item
> (subject) of the triple isn't necessarily a class.


okay, I have always assumed that the subject *is* a class, any hints as to
what are my options?
or what chapter of the book/tutorial I can find the relevant info?



> Second, the terms 'relation' and 'attribute' are not used in RDF, though
> they are both used more widely to mean what RDF calls a property.
>

yeah, well.  I am trying to match the UML and E/R view of the world into
RDF. i understand that some plugins will convert UML into RDF or OWL, but I
do not want to trust machine just yet (plus I have to learn to use these
other tools first)


Can you give some examples of the kind of contrast you have in mind here?
>


One of the working example below. See either l diagram below (probably not
the final version, just a working draft of it). I mean I can get other
people to rdfize a model, but I am trying to see what barriers I hit if I do
it myself by hand (exercise)

http://www.w3.org/2005/Incubator/eiif/XGR-Framework-20090806/

scroll down to FIG 7

So, to sum up, after realising that we can use RDF equall to triplify

ORGANISATION   HAS     CONTACDETAILS
(class)                   rel        (class)


but also

ORGANISATION     IS        OFTYPE

or
ORGANISATION     HAS    WEBSITE



is this 'versatility' of using RDF in the same way for either/both

a) what is referred to as an RDF weakness?
b) never been thought of as a problem when modelling data?
c) related to the intensional /extensional discussion referred to as above?



Finally, not sure to what thread the observation pertains, that developers
manage to find workaround to 'non optimal'
representation issues. Yes, we can find workarounds, but on a large scale,
repeated over a period of time these
can cost massively, at some point it may be worth considering addressing
weaknesses to reduce the instability
of systems that may built around our workarounds :-)

And if this is just too boring for others, happy to take the rest of this
convesation offlist

thanks in advance

PDM




>
>  ),
>
>