Re: RM VERY STRONG SUGGESTION 4: TRANSITION CONSTRAINTS

On Sep 9, 9:54 am, paul c <toledobythe..._at_oohay.ac> wrote:
> On 08/09/2010 7:41 PM, Brian wrote:
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> > On Sep 7, 8:23 pm, paul c<toledobythe..._at_oohay.ac>  wrote:
> >> On 07/09/2010 3:14 PM, Reinier Post wrote:
>
> >>> Brian Seltzer wrote:
>
> >>> [...]
>
> >>>> There is a mapping from every tuple in a database to something in the
> >>>> microworld that is being modeled, but more importantly, every tuple
> >>>> maps to something that has a location in time if not also space.
>
> >>> Where exctly is 'there'?
>
> >> That doesn't matter.  There is no useful mapping unless it is recorded.
> >>    Eg., there is not 'time' in a db unless it is recorded. Brian S has a
> >> mental block about this.  (For the sake of newcomers, this needs to be
> >> repeated once in a while.  We all have various mental blocks, but most
> >> of us stop harping about them after a while.)
>
> > When I'm wrong, I admit that I'm wrong.  I don't think I'm wrong, and
> > nobody has offerred an irrefutable argument that proves me wrong;
> > therefore, I have to conclude that I'm right.
>
> > As Codd has written, and as Bob Badour continually asserts every time
> > the subject of surrogate keys comes up: Every key is a surrogate.  A
> > surrogate for what?  For an object in the microworld being modeled.
> > Every tuple has a superkey consisting of all prime components; every
> > key is a surrogate; therefore every tuple has a surrogate.  A
> > surrogate for what?  For an object in the microworld being modeled.
> > If that doesn't constitute a mapping, then perhaps you can enlighten
> > me as to what does.
>
> Heh, fat chance, you'd have to give up your mutating tuples and other
> sci-fi like microworlds and unnecessary mapping notions first.
>
> Actually, surrogate isn't an important term for RT since it means merely
> that every key is just a surrogate for other keys, ie., the term has not
> much practical leverage.  I'd guess the stackoverflow crowd who relish
> obfuscation might get shrill about that, maybe you too, but I can't help
> it if my first language is English.
>
> It's too bad about Codd's early phrase, how 'time-varying' makes some
> people imagine that his theory depends on time.  I think it was just a
> metaphor to help his explanation.  Even Date perseveres with 'update'
> which seems to make people think of time.  Replace would have been a
> better word.
>
> Whether in art or computer science, every medium introduces its own
> restrictions, Codd's intended medium depends on extreme abstraction, the
> elimination of as many concepts as possible for its leverage.  The
> leverage means wider application but it's not universal, eg., not a very
> good medium for poetry.
>
> Date has said that a db language without assignment is a kind of cheat
> but he tempered that by acknowledging that his chosen medium involves
> 'imperative' languages (same as procedural I think).  I think it's best
> to keep assignment out of Codd's theory.  The reason is none other than
> it's not necessary to understand his theory.  Implementation devices
> could just as easily include one-time variable assignments as they could
> Date's repetitive assignments.  Too bad I wrote 'one-time' but the
> English medium has its restrictions too.- Hide quoted text -
>
> - Show quoted text -

I suggest you read Hugh Darwen's book, /An Introduction to Relational Database Theory/. It's available for download online. See the TTM web site. After you read his book. Maybe you'll understand how ridiculous this post makes you sound.

As for having a mental block. Trying to model database updates using functional programming is like trying to milk a steer. Good luck with that! Received on Thu Sep 09 2010 - 23:37:02 CEST