Re: plural vs singular properties (a proposal)

Garret--
Part of the confusion is that you've changed the example. In your 
original example, you were talking about only one book (there was 
only one rdf:Description, so you were describing only one resource). 
That's what I responded to. However, let's continue with your 
example below. If you want to add a dc:subject of "airplanes" for 
"mybook" to the information you have, there are two choices.
Choice #1:
Add the tuple [ <...#mybook> "My Book" "airplanes" ] to the 
relation you have, forming
+----------------+----------------+----------------+
| URI | dc.title | dc.subject |
=================|----------------|----------------|
| <...#mybook> | "My Book" | "semantic web" |
| <...#yourbok> | "Your Book" | "database" |
| <...#mybook> | "My Book" | "airplanes" |
...
This is a unique tuple (it doesn't duplicate any of the others), but 
normalization principles frown on this, because you duplicate the 
fact that <...#mybook> has a dc:title of "My Book".
Choice #2:
Create a normalized design with two relations (tables):
dc:title (the table name)
+----------------+----------------+
| URI | value |
=================|----------------|
| <...#mybook> | "My Book" |
| <...#yourbok> | "Your Book" |
| <...#mybook> | "My Book" |
...
dc:subject (the table name)
+----------------+----------------+
| URI | value |
=================|----------------|
| <...#mybook> |"semantic web" |
| <...#yourbok> | "database" |
| <...#mybook> | "airplanes" |
...
This normalized design is in fact what is represented in RDF, only 
RDF uses triples, which is a notation that is equivalent to adding 
the relation name to each (binary) tuple, rather than separating 
things into tables.
--Frank
On Jan 5, 2008, at 11:49 AM, Garret Wilson wrote:
> Frank Manola wrote:
>>
>> Assuming I understand what you're talking about, this *isn't* a 
>> conflict with the relational model. To flesh out your example a 
>> bit, suppose you have a paper, book, or article, and want to 
>> record subject descriptors.
>
> I don't yet understand what you're talking about in your reply, so 
> while I read it again several times, let me just clarify my 
> original concern which apparently wasn't as clear as I thought it was.
>
> Let's say I have the following relation, complete with header and 
> body:
>
> +----------------+----------------+----------------+
> | URI | dc.title | dc.subject |
> =================|----------------|----------------|
> | <...#mybook> | "My Book" | "semantic web" |
> | <...#yourbok> | "Your Book" | "database" |
> ...
>
> Now, if <...#mybook> has a dc:subject of "airplanes" in addition to 
> its dc.subject of "semantic web", where do I put that in the 
> relational model? I can't add another "table column".
>
> I'll go read your response again in the meantime.
>
> Thanks,
>
> Garret