# Re: In an RDBMS, what does "Data" mean?

Date: Mon, 14 Jun 2004 23:24:28 +0100

Message-ID: <ZoGxRIEcWizAFwDp_at_thewolery.demon.co.uk>

In message <An3yc.2600$FE6.1451_at_newssvr15.news.prodigy.com>, Eric Kaun
<ekaun_at_yahoo.com> writes

>"Anthony W. Youngman" <wol_at_thewolery.demon.co.uk> wrote in message

*>news:8jbIDPPhC7xAFwHy_at_thewolery.demon.co.uk...
**>> In message <lgGxc.6818$eP2.1437_at_newssvr32.news.prodigy.com>, Eric Kaun
**>> <ekaun_at_yahoo.com> writes
**>> >And as stated elsewhere, those aren't axioms anyway... he used the word
**>> >"representation", and the context fully suggests that he's not
**>correlating
**>> >it with the real world.
**>> >
**>> I know. After writing that I thought rather more about what C&D's twelve
**>> rules actually are. And that they don't seem to contain any axioms at
**>> all.
**>>
**>> Which leads to the conclusion that relational theory is axiom-free.
**>> Which means that it cannot be a valid model.
**>
**>Some possibilities (I'm running too short on time to explore them):
**>- The axioms may be simply implicit in his rules
**>- What are MV's axioms? If it has them, then we could map at least some of
**>them to relational (since there are commonalities)
*

If they're implicit, then they need to be made explicit (hence my
comment about mathematicians "fleshing out" the theory).

*>
**>> Which means that its
**>> application to the real world has no basis in anything whatsoever.
**>
**>Maybe, but again, what sort of data model would have axioms? I'm not sure
**>this is possible... and if it is, again, relational would somewhat-similar
**>ones. Surely there's at least a partial homomorphism between data models?
*

The generic always trumps the specific. I suspect Pick axioms are very
similar to relational. But just as C&D's first rule says that data comes
in 2-dimensional tables (or arrays), I've defined "Pick's first rule"
that says data comes in n-dimensional arrays. So relational is the
specific subset of Pick where n=2. :-)

*>
**>> Okay, I'm sure that the mathematicians who've built on it have fleshed
**>> out the fundamentals somewhat, but it certainly means that if your sole
**>> criteria for defining a "relational database" is that "it complies with
**>> C&D's 12 rules", then such a database has no grounding in formal logic
**>> whatsoever.
**>
**>Mathematics requires axioms - does logic? I thought it was purely symbolic
**>manipulation, which is defined for relational.
**>
*

Logic is used to manipulate axioms to give theorems. The result is a
model.

Cheers,

Wol

-- Anthony W. Youngman - wol at thewolery dot demon dot co dot uk HEX wondered how much he should tell the Wizards. He felt it would not be a good idea to burden them with too much input. Hex always thought of his reports as Lies-to-People. The Science of Discworld : (c) Terry Pratchett 1999Received on Tue Jun 15 2004 - 00:24:28 CEST