JOG wrote:
> On Feb 16, 4:40 am, Joe Thurbon <use..._at_thurbon.com> wrote:
>
>>David BL wrote:
>>
>>[...]
>>
>>PMFJI, but I think there is an essentially definitional misunderstanding
>>here. Although, you know, I'm only new at this, so take it with a grain
>>of salt. I'm really interrupting to see if I'm getting a better
>>understanding of all this, and I do so with some trepidation.
>>
>>The word that I think is being used extremely loosely is 'entity'.
>>
>>In your post you use it to describe, variously,
>>
>>- integers,
>>- relations,
>>- elements of any set,
>>- things that we want to model with a relational theory*
>>
>>and a term that can be used to describe anything is basically useless.
>>
>>*BTW, I'm using theory here in the sense of a logical theory, i.e. a set
>>of constants, functions, domains, etc. In this post, I'll not use theory
>>in any other sense.
>>
>>I'm pretty sure that Jim is using 'entity' to describe 'things that we
>>might agree exist in the real world', or at least, things outside the
>>relational theory at hand. An in particular, I think that things that
>>exist within the theory are not entities, by definition.
>>
>>Although Jim should feel free to correct me if I'm putting words into
>>his mouth.
>
>
> No you are pretty much on the money there imo Joe.
>
> 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.
If we have entities, then we have to accept that the book is nothing
more than a property of the cover type entity.
Received on Fri Feb 16 2007 - 10:04:51 CST
