Re: Can we solve this -- NFNF and non-1NF at Loggerheads

"Paul" <paul_at_test.com> wrote in message news:4207afa3$0$55486$ed2619ec_at_ptn-nntp-reader02.plus.net...
> Alan wrote:
> >>I don't see a conflict between the extract below and what Roy said
> >>above. Just that the text below is a bit on the verbose and practical
> >>side, and the above is a more abstract, concise and clear version.
> >
> > Then you better re-read the "more abstract, concise, and clear"
inaccuracy
> > that Paul wrote. Here, I'll make it easy:
> >
> > Paul:
> > "There is nothing in RT that *prevents* values from being
> > divisible, there never was, and it would plainly be stupid to
> > want it that way."
>
> (just to point out these words were Roy's, not mine, though I agreed
> with them)

Sorry. I lost track of that. Please accept my apology. I certainly would not want to attribute that quote to anyone other than who stated it.

>
> > Alan, via Elmasri/Navathe:
> > "...it was defined to disallow multivalued
> > attributes, composite attributes, and their combinations. It states that
the
> > domain of an attribute must include only atomic (simple, indivisible)
> > values..."
> >
> > There is no way to interpret other than how it was written.
>
> I think the misinterpretation is over what model or universe of
> discourse we are discussing. The first quote is saying that values are
> atomic or indivisible from the point of view of the relational part of
> the RDBMS. But it's saying they could be divisible in some much larger
> model of which the relational model is but a small part. And that this
> is outside the scope of the relational model, so we ignore it.
>
> As someone else said in another thread:
>
> Chemistry: atoms are indivisible!
> Physics: atoms are divisible!
>
> neither are wrong, they are just looking at things from a different
> perspective.
>
> > What Paul and everyone else is talking about, but can't articulate, is
that
> > there is another theory/model, with the (in?)formal name of "Nested
> > Relational Model", or NFNF (Non First Normal Form). This is the
model/theory
> > where the restriction of 1NF is _removed_, not redefined (Elmasri, page
> > 459).
>
> I think there are 3 models:
>
> 1. Standard Codd-style relational model based on pure first-order
> predicate logic, where relation-valued attributes are only allowed if
> the relational operators in the DBMS don't know they exist. To look
> inside them requires domain operators.
>
> 2. Date's amended relational model, where relational-valued attributes
> can exist, and additional relational operators are introduced to enable
> the DBMS to look inside these relational-valued attributes.
>
> 3. A Pick-style model (often called "non-first normal form" or NFNF),
> which essentially enables any attribute to be a list of values (I
> think). I'm not so familiar with this but I think that instead of a row
> repesenting a proposition like this:

Can't speak to the PICK part, but I agree with the idea that #1 and #3 are distinct models. I suggest that #2 is also a distinct model, not a replacement for #1. BTW, Date has, on occasion, admitted to being in error.

>
> PERSON has tel no TEL and email address EMAIL
>
> it represents propositions like this:
>
> PERSON has tel nos [TEL1, TEL2, ...]
> and email addresses [EMAIL1, EMAIL2, EMAIL3, ...]
>
> where I think these are ordered lists (correct me if I'm wrong)
>
> >>I don't think most of the people here actually disagree with the basics,
> >>just that there is a problem with expressing the ideas in written
> >>language such that they aren't misinterpreted.
> >
> > Nonsense. Of course they disagree, that's what we've been arguing about.
> > I've cited well-respected, published proof of my argument, and until
someone
> > can present well-respected published proof (and not just on the internet
> > where one could find "proof" of little green men from Mars) of their
> > argument, they should keep quiet. Or apologize.
>
> I don't think this is the kind of question that admits a "proof"
> unfortunately - it's all about how things are interpreted.

I am not using "proof" in the mathematical/logical/philosophical way. I mean show me something that is either in a peer-review journal, or has been accepted at universities as a text book. Sure, scholars can disagree, so I would expect something to be found somewhere. Something more than opinion, IOW.
>
> Paul.
Received on Mon Feb 07 2005 - 19:40:35 CET