Re: some information about anchor modeling

From: vldm10 <vldm10_at_yahoo.com>
Date: Wed, 28 Nov 2012 00:54:33 -0800 (PST)
Message-ID: <0bb74c72-ad30-4983-a6d9-23799a697f6c_at_googlegroups.com>


On Monday, November 5, 2012 11:10:05 PM UTC+1, Eric wrote:
> On 2012-11-04, vldm10 <vldm10_at_yahoo.com> wrote:
>
> ...
>
> >> Google gives a Safari book preview of a few lines, below. (I have the
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> >> book, this enough to give you an idea of his usage, introduced here.) See
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> >> http://en.wikipedia.org/wiki/Relational_Model/Tasmania re kernel entities
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> >> of RM/T.
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>
>
> > Let me comment only few basic things from this web site. In the section
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> > "Summary of RM/T", the following basic concepts are defined:
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>
>
> (re-ordered)
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>
>
> > (ii) Definition
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> > A nonentity is some thing that is not an entity?
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> >
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> > my comment: Note that ?entity? and ?thing? are synonyms.
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>
>
> Selective quoting is never a good way to try to make a point. The
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> sentence before says "An entity is some thing in the modelled universe",
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> i.e. a definition if "entity" in the current context. A thing that is
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> not in the modelled universe is not an entity so the two words are not
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> synonyms. Simple.
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>
>
> >
>
> > (i) Definition
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> > Surrogates. A surrogate is a unique value assigned to each entity.
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> >
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> > my comment: The entity is the real world object and it is not possible
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> > to assign value to the real world object.
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>
>
> I can assign value to anything I choose. I can make my system assign *a*
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> value to its representation of an entity. There are two distinct
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> meanings of "value" there. Either way your comment is just wrong.
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>
>
> > (iii) Definition
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> > The RM/T addresses atomic semantics by?
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> >
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> > my Comment: With the most carefully observing the RM / T, one could not
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> > find a single atom of the semantics, because in the RM/T, section 4,
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> > E. Codd wrote: "Database users may cause the system to generate or delete
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> > a surrogate, but they have no control over its value, nor is its value
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> > ever displayed to them.?
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>
>
> There are various things one could say about Codd's statement you have
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> quoted, but what the blazes has it got to do with atomic semantics? I
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> suspect that you have totally misunderstood the meaning of "atomic
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> semantics" in the context of that web page.
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>
>
> Or, to put it another way, nothing you are saying makes any sense at
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> all.
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>
>
> Eric
>
> --
>
> ms fnd in a lbry

I did not use “selective quoting”, I wrote about surrogate keys, entities and atomic semantics. These are the basic concepts of RM/T. In fact, I wrote about nonsense in the paper RM/T.

For example, the following sentence: “An entity is some thing in the modelled universe and is typically identified by a surrogate.” is not true, because Codd’s surrogate does not identify an entity. In many cases, the surrogate introduced by E. Codd, cannot identify anything. In fact, Codd’s surrogate is serious nonsense. The paper RM/T has many other mistakes; some of these mistakes are related to fundamentals from the theory of database.

I am writing about this, because I have impression that there are people who try to “fix” RM/T paper, by using works which are done by others. Note that these are the most important things from the theory of database.

Vladimir Odrljin Received on Wed Nov 28 2012 - 09:54:33 CET

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