Re: Mixing OO and DB

From: JOG <jog_at_cs.nott.ac.uk>
Date: Tue, 12 Feb 2008 04:53:20 -0800 (PST)
Message-ID: <9ee041b4-9546-40b0-81fe-54445a216b97_at_d21g2000prf.googlegroups.com>


On Feb 12, 5:37 am, David BL <davi..._at_iinet.net.au> wrote:
> On Feb 12, 10:01 am, JOG <j..._at_cs.nott.ac.uk> wrote:
>
>
>
> > On Feb 11, 4:10 pm, David BL <davi..._at_iinet.net.au> wrote:
>
> > > On Feb 11, 11:08 pm, JOG <j..._at_cs.nott.ac.uk> wrote:
>
> > > > 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:
>
> > > > > > On Feb 11, 2:05 am, David BL <davi..._at_iinet.net.au> wrote:
>
> > > > > > > On Feb 11, 3:29 am, JOG <j..._at_cs.nott.ac.uk> wrote:
>
> > > > > > > > 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.
>
> When you say "meaningless binary value", are you suggesting a value
> can exist independently of its type?

I am suggesting that 10001 is a binary number, no more and no less, until you apply some meaning to it and hence turn it into data. Same with a picture. Until you say something about it, its just a picture value.

Consider /unallocated/ RAM in your PC. Look at 5 contiguous bits at random. Are you telling me that the binary number you are looking at is "data"? I'd accept that it is a value (albeit a meaningless one) but "data"? You really think that?

>
> > > 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".
>
> Let me use an example: I give you a disk with some data, tell you a-
> priori that it records a string, describe the format and you are able
> to determine that the recorded value is a poem
>
> "Is it binary or is it data?
> Is it info or knowledge,
> or is it wisdom -
> the whole enchilada?"
>

Thats a value imo, and its only data if we say "The file myPoem.txt contains 'Is it binary or is it...'". I do realise that the definitions I am suggesting as formal are at odds to the handy wavy, nebulous way we throw around terms such as 'data', 'data model', etc.

As proof (!) consider your above example if you placed the poem written on paper in front of me. Are you telling me that is data? Course not, its just a poem written down - a value. So then what is the difference between this and your example on a disk? That its encoded in binary?

> Note that no additional context has been provided. I would say the
> purpose of the data was to convey a value, but not to convey a fact.
>
>
>
> > > 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.
>
> C.Date distinguishes between a value (that by definition doesn't exist
> in time and space), versus the *appearance* of a value which appears
> in time and space and is encoded in a particular way.

Is this what your view of the terms is based upon?

>
> I would suggest that data should by definition be regarded as
> synonymous with the appearance of a value.
>
> If you don't agree with that, then let's treat it as a definitional
> matter. However I'm curious to know what you would say is the
> distinction.

Yes, sure, this is just definitional. However I am on the side of traditional scientific notion of data ("On the third experiment the electrical current was x amps"), as well as Codds! Regards, J.

>
> > 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).
>
> I don't agree with that definition of "data". Particular integers
> don't tend to be interesting in their own right, so we never record
> them without a context. However that is not true for more complex
> value types, such as strings or images.
Received on Tue Feb 12 2008 - 13:53:20 CET

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