Re: Objects and Relations

On 19 fév, 02:01, "David BL" <davi..._at_iinet.net.au> wrote:
> On Feb 18, 12:36 am, "JOG" <j..._at_cs.nott.ac.uk> wrote:
>
>
>
> > On Feb 17, 3:05 pm, "David BL" <davi..._at_iinet.net.au> wrote:
>
> > > On Feb 17, 12:18 am, "JOG" <j..._at_cs.nott.ac.uk> wrote:
>
> > > > On Feb 16, 4:40 am, Joe Thurbon <use..._at_thurbon.com> wrote:
> > > > > David BL wrote:
> > > > I am happy to put up with the definition of an entity describing a set
> > > > of attributes/value pairs. All I object to is the concept that these
> > > > sets are anything but arbitrary collections.
>
> > > > To some people a 'book' requires an attribute stating whether it is a
> > > > hardback or a softback. In other contexts a book might just be
> > > > composed of its title, its content, etc. (a book published online
> > > > perhaps). Please don't dwell on this example, it is just off the top
> > > > of my head to show that 'entities' are artifices and vary incredibly
> > > > from person to person and context to context. So as far as data
> > > > management is concerned, keep 'entities' out, and let humans resolve
> > > > such concepts outside of the logical model.
>
> > > You seem to be focusing on entity as meaning an abstract type, whereas
> > > I'm tending to think of an entity as a particular thing.
>
> > Your definition is meaningless as has been pointed out by several
> > people. entity = particular thing, just begs the question of what a
> > 'thing' is. You seem to have a circular definition that a thing = a
> > particular entity.
>
> Are you making a real attempt to understand me? That's a trivial
> strawman. It clearly wasn't a definition. It was in reference to
> your book example. For the purposes of stating facts about books, an
> entity would be a particular book, not some type "book".
> Classification is not necessary. It is irrelevant to the discussion.
>
> > > Why are you doing that?
>
> > I am trying to help you to a better definition, from which the limits
> > of thinking in terms of 'entities' becomes clearer.
>
> I can't understand your point. From my perspective you appear to make
> the simple mistake of thinking that because it's difficult to classify
> things, things don't exist!
>
> I ask again, what's you point about the difficulties of
> classification?
>
>
>
> > If it helps given the E/R-style 'entity' terminology you are holding
> > onto, you might consider that I view /everything/ as an "associative
> > entity". But of course I would not call it that.
>
> > > It is well known that classification of entities is
> > > adhoc. Fortunately In DB systems we tend to state facts about
> > > particular things far more often than sets of things.
>
> > > If I were to place an actual book in front of you, you could think of
> > > hundreds of objective propositions about it. Actually the number of
> > > possible propositions you could state about the book would seem almost
> > > unlimited.
>
> > > If you were given a different book, again there would be countless
> > > propositions you could state about it. Now the book may have some
> > > fundamental differences. Therefore attributes relevant to the first
> > > book may not make sense for the second book and vice versa. This
> > > makes classification of books difficult. However we both agree that
> > > the RM copes well with that because it can represent knowledge about a
> > > single book across lots of different relations. RM has no need to
> > > develop a class hierarchy in the manner of OO (or indeed E/R
> > > diagrams).
> > It is good we are agreed of the benefit there, and an important point
> > not to forget in all of this.
>
> > > What is more fundamental - facts about a particular entity, or the
> > > entity itself? Surely the facts are secondary - at least for physical
> > > entities.
>
> > Well of course I don't accept there is anything but facts and values,
> > so your question is nonsensical to me.
>
> I guess your statement that entities are illusionary is nonsensical to
> yourself as well then.
>
> > Remember that there are practical evidence of this standpoint having
> > merit. For instance Symbolic AI died in the 1970's - a very real,
> > practical example of how tyring to manipulate these elusive 'entities'
> > results in failure. Situated and Nouvelle AI was born from this and
> > I'd encourage you to check this area out - "Elephants don't play
> > chess" by Brooks, is a good starting point.

Don't you realize that BobBadour expects your total obedience and is not interrested a bit in what you are saying...You can either obey and be a Marshall or simply stick to your ideas until convinced otherwise and be *intelectually dishonnest* and all and all... Received on Mon Feb 19 2007 - 08:23:40 CET