Re: Mixing OO and DB

On Feb 12, 10:49 am, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> "JOG" <j..._at_cs.nott.ac.uk> wrote in message
>
> news:27321846-87df-4f21-a7bd-382d8b7d6605_at_m34g2000hsf.googlegroups.com...
>
>
>
>
>
> > On Feb 12, 1:01 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.
>
> >> > 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?
>
> Isn't a datum an atomic value? I think I remember reading somewhere, "Each
> and every datum (atomic value)...."
>
> I think the distinction you want to make is whether or not some individual
> that is represented by the value 73 actually exists. For that there needs
> to be a context. If the value 73 from the domain of integers is named in a
> tuple in a relation in a database, then clearly that particular instance of
> the value 73 has a context and thus maps to an actual individual in the
> picture of the universe of discourse that is the database. Clearly the act
> of storing the value 73 gives it context. Without context, 73 is a possible
> value, not an actual value.

Instance of a value? Context of a value? Possible value? Actual value? I cannot make sense of that. There is a theorem that states that the integers are unique up to isomorphism. It is customary to say there is only one integer with the value 73.

Rather than "instance of value", I think you mean "appearance of value". However I still can't follow the rest. Received on Tue Feb 12 2008 - 07:21:33 CET