Re: Another view on analysis and ER

On Dec 10, 6:33 pm, Jan Hidders <hidd..._at_gmail.com> wrote:
> On 9 dec, 22:10, JOG <j..._at_cs.nott.ac.uk> wrote:
>
>
>
> > On Dec 9, 5:20 pm, Jan Hidders <hidd..._at_gmail.com> wrote:
>
> > > On 9 dec, 04:04, JOG <j..._at_cs.nott.ac.uk> wrote:
>
> > > > Now in ontology, it is generally accepted that an
> > > > object, or entity, is nothing more than a compressence of a collection
> > > > of properties - i.e. (attribute, value) pairs.
>
> > > [....]
>
> > > I'm also not comfortable with the usage of "is" here. I'd agree that
> > > this is how entities can be described, but saying that they "are"
> > > these descriptions seems wrong to me.
>
> > Why are you uncomfortable with that. An entity is nothing more and
> > nothing less than the 'compressence' of its _full_ set of all its
> > attributes.
>
> > > After all, different descriptions may describe the same entity.
>
> > Well, I haven't talked about describing entities, rather we're
> > defining them. This is an entity as our model sees it, not how it is
> > seen in the real world (obviously there are concessions, given the set
> > of possible attributes is probably infinite).
>
> But that is what I'm saying, isn't it? These sets of properties are
> part of your model of a piece of reality and as such *represent*
> entities that are part of that reality, Saying that they *are* these
> entities is sloppy use of language and confuses the map with the
> territory. If I didn't know any better I'd almost think you could be
> accused of muddled thinking. :-)

I should think you mean muddy, not muddled sir! But while I see what you are refering to of course, I'd defend myself by returning to a differentiation i tried to make in the past, between 'constructs' and 'entities'. I preferred the use of the term 'constructs' because it highlights we are defining these things in our models (not that this makes them any less real), and detaches people from what they might view an entity to be in the wild as it were. Pick constructs that don't tally with the entities that your trying to keep track of and you end up with a crappy schema. This is exactly where I think people go wrong when considering change (and hence up in the OID or substance theory mistake). I don't hold up much hopes for getting people to change terminology, but hey, you never know ;)

>
> I'm afraid I have to leave it at that today because duty is calling. I
> picked this point because it seemed important and yet something we
> might soon agree on. If you want you can indicate which point you'd
> like me to address first after this one.

Well I guess I'm interested in a discussion of the introduction of role-names into relationships. It has always seemed to me that their inclusion takes one very much away from mathematical predicates, and into viewing the relationship as (dare I say it) an entity in terms of FOL. Something is up Jan and you know it! There is an answer to a formal model of semistructure, missing data and such like buried in here somewhere.

>
> -- Jan Hidders
Received on Tue Dec 11 2007 - 02:13:20 CET