Re: Mixing OO and DB

From: David BL <davidbl_at_iinet.net.au>
Date: Mon, 11 Feb 2008 22:02:41 -0800 (PST)
Message-ID: <a1a797dc-1258-4798-a05d-4c94a9778017_at_e6g2000prf.googlegroups.com>


On Feb 12, 10:14 am, JOG <j..._at_cs.nott.ac.uk> wrote:
> On Feb 12, 1:01 am, JOG <j..._at_cs.nott.ac.uk> wrote:
>
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> > On Feb 11, 4:10 pm, David BL <davi..._at_iinet.net.au> wrote:
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> > > On Feb 11, 11:08 pm, JOG <j..._at_cs.nott.ac.uk> wrote:
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> > > > On Feb 11, 12:44 pm, David BL <davi..._at_iinet.net.au> wrote:
>
> > > > > On Feb 11, 8:07 pm, JOG <j..._at_cs.nott.ac.uk> wrote:
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> > > > > > On Feb 11, 2:05 am, David BL <davi..._at_iinet.net.au> wrote:
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> > > > > > > On Feb 11, 3:29 am, JOG <j..._at_cs.nott.ac.uk> wrote:
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> > > > > > > > On Feb 10, 5:45 pm, "Dmitry A. Kazakov" <mail..._at_dmitry-kazakov.de>
> > > > > > > > wrote:
> > > > > > > > > [What is data, in your opinion?
>
> > > > > > > > Data. Lots of datum - from latin, meaning statement of fact. Predicate
> > > > > > > > and value in FOL. A value without description is of course just
> > > > > > > > noise.
>
> > > > > > > Latin datum is past participle of dare, "to give". What make you say
> > > > > > > data is necessarily a set of propositions?
>
> > > > > > The OED. "Facts, esp. numerical facts, collected together for
> > > > > > reference or information." The etymology stems from 'dare', because
> > > > > > facts are always communicated or "given". I understand of course that
> > > > > > the term is thrown around wantonly and ambiguosly nowadays, but as
> > > > > > data theorists, we shouldn't be party to that imo ;)
> > > > > > > Are you suggesting a value
> > > > > > > is meaningless without a proposition? Why can't a datum just be a
> > > > > > > value?
>
> > > > > > Because ta value has to be associated with something. Hofstadter gave
> > > > > > a good example of this with the groove modulations on a vinyl record.
> > > > > > To us they are (musical) data, to an alien not knowing their context,
> > > > > > it is not. You need the context.
>
> > > > > > > Wouldn't you say a recorded image is data?
>
> > > > > > Of course, so long as I know it's an image. If its just ones and
> > > > > > zero's stored in a computer, without anyway of telling they represent
> > > > > > a picture, then it is simply noise.
>
> > > > > Let's indeed assume we know how to interpret the 1's and 0's as an
> > > > > image. So what have we got? Nothing but a *value*.
>
> > > > No, you now have a value with applied context. That creates a fact.
> > > > You now therefore have data. It's simple to show - consider "1000001".
> > > > Thats currently a value, but its not data. Its only data when I store
> > > > it, and state one of the following:
>
> > > > "100001" is a text string
> > > > "100001" is an integer (i.e. 65)
> > > > "100001" is an ascii character (i.e. A)
> > > > etc..
>
> > > These "facts" are all tautologies that are true whether you record
> > > them or not.
>
> > I'm not seeing whats so controversial or difficult about the fact that
> > "10001" is just a meaningless binary value until you give it a
> > context. It seems somewhat obvious to me.
>
> > > I dispute your premise that the purpose of the data in
> > > this case is to state a fact that is known a-priori to be true.
>
> > A Datum is a given fact. That's what the word means formally. I have
> > said nothing more, and I have no idea what you are on about talking
> > about "the purpose of data".
>
> > > If that is its purpose then it conveys precisely zero information.
>
> > > > > We can display
> > > > > it. We can comment on whether we like it - even if we haven't a clue
> > > > > where it came from. But I don't see any sense in which the image
> > > > > value gives us any statements of fact beyond the specification of a
> > > > > value. A value simply "is".
>
> > > > > I would suggest that a lot of the data in the world is characterised
> > > > > more closely as "interesting values" than collections of
> > > > > propositions.
>
> > > > You cannot store these interesting values without implicitly stating
> > > > some fact about them.
>
> > > By definition, when a value is specified, its type is specified as
> > > well (except possibly if type inheritance is supported).
>
> > > C. Date states the following in "Introduction to Database Systems",
> > > section 5.2, and subsection titled "Values and Variables are typed":
>
> > > "Every value has ... some type...Note that,
> > > by definition, a given value always has
> > > exactly one type, which never changes.
> > > [footnote: except possibly if type
> > > inheritance is supported]"
>
> > > When a particular value like the integer 73 is specified, there is no
> > > implicit fact being specified. The statement that the integer 73
> > > exists in any absolute sense is entirely metaphysical and meaningless
> > > within computer science.
>
> > So you just wriite "73" down and are telling me its a datum? I'm
> > pretty sure that's what we call a "value", not data. I'm wondering if
> > you are misconstruing my point - "73" is only data when you apply some
> > context to it, like saying this its someones room number, or today's
> > average temperature, or the amount of red in a certain pixel of an
> > image (and yes, those are then facts).
>
> Let me clarify the distinction I'm making David:
> "RED" is a value.
> "The first pixel in the image is RED" is a datum.
>
> That can't be that contentious...can it?

I assume this is an image with enumerated colour values for pixels, and first pixel means "top,left" or something like that.

I'm a little suspicious of "the image". An image is a value and values are self identifying.

Anyway, I don't understand the point you are making. I think of an image as a value, and one can state all sorts of tautologies about values. Eg

        The string "hello" is a prefix of the string "hello world" Received on Tue Feb 12 2008 - 07:02:41 CET

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