Re: Mixing OO and DB

On Feb 18, 2:54 pm, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> "JOG" <j..._at_cs.nott.ac.uk> wrote in message
>
> news:9098871a-bd2c-4385-b547-542f38b2055a_at_34g2000hsz.googlegroups.com...
>
>
>
> > On Feb 15, 2:31 am, David BL <davi..._at_iinet.net.au> wrote:
> >> On Feb 14, 10:38 pm, JOG <j..._at_cs.nott.ac.uk> wrote:
> >> [snip]
> >> > On Feb 14, 3:52 am, David BL <davi..._at_iinet.net.au> wrote:
> >> > "todays lottery numbers: 23, 34, 17"
> >> > "experimental results: 23, 34, 17"
>
> >> > All written down on a bit of paper - same values discussed, but
> >> > different data. Agree or disagree?
>
> >> I agree. Yes, same values but different data
>
> >> > I ask this because if we can distinguish data and values, we must then
> >> > determine /how/ they are different. You state it is by "encoding" but
> >> > the two lines above are encoded in the same manner as far as I am
> >> > concerned, so that cannot be the difference between the two concepts.
> >> > That is unless your "Encodings" equates to my notion of "Facts", and
> >> > we are thus agreeing loudly, using different definitions of those
> >> > terms.
>
> >> They are the same values and they are encoded in the same manner.
> >> However they are distinct appearances, hence distinct data.
>
> > Ok, so we're agreed at least there. Same values with the same
> > encoding. Yet the first datum is different to the second. The logic
> > below therefore follows:
>
> > 1) The two items of data discussed have the same values and same
> > encoding.
>
> Yes.

Hey Brian. That's good - at least there is consensus there.

>
> > 2) The two items of data can obviously be distinguished (we are agreed
> > they are not the same data).
>
> No. They are the same data.

Ok, that I personally find a strange use of the term. You seem to be saying that:

P(a, b)
Q(a, b)

is the same data? To me that looks like the first line is a different datum to the second, even though they share the same values. Definitely not in your opinion?

>
> > 3) Therefore a datum must possess some attribute outside of its values
> > and encoding.
>
> Yes, but not what you think: A fact is supposed to be true.
>
> Each appearance of a value in a proposition that is supposed to be true is
> data, but each appearance in the same proposition is the same data.
> But isn't it also true that at least some combinations of values, such as those
> combinations of values that appear in a tuple, may also be data?
>
> Let me try to be absolutely clear here:
>
> Let a and b be constant symbols;
> Let x and y be free variables;
> Let P and Q be predicate symbols.
>
> Then if Pxy is a predicate with two free variables that range over the same
> domain, then Pab is a literal that can appear in the extension of Pxy by
> substituting the constant a for every appearance of the free variable x in P
> and the constant b for every appearance of y.
>
> Let's let constant symbols also be literals.
>
> So b is a literal; Pab is a literal; Pbb is a literal; and so on.
>
> A literal that is supposed to be true is an atomic fact.
>
> Assuming that Pab is supposed to be true, then b indicates that the
> individual that b maps to exists, a indicates that the individual that a
> maps to exists, and Pab indicates that both a and b participate in the
> relationship P. Pab depends upon a and b, but Paa could also be true, and
> so could Pbb, and so could Qab; so it is safe to say that the literals Pab,
> Pbb and Qab would only indirectly indicate that the individual that b maps
> to exists, although each would convey a distinct atomic fact concerning that
> individual.

Ok, riding with it for a moment, If I follow correctly, you are saying that, P(a,b) -> Exists(a) & Exists(b). That certainly seems entirely sensible.

>
> Now if Pab appears in a proposition that is not supposed to be true, then it
> cannot be determined whether b maps to an individual that exists or that a
> maps to an individual that exists. It may be that they do, but that they
> just don't participate in the relationship, P, or for that matter, it may be
> that the literal Pab also appears in a proposition that is supposed to be
> true.

Yes, in the case ¬P(a,b) no conclusions can be made concerning the existence or non-existence of a and b. That too seems sensible.

> Whether a literal is supposed to be true depends upon whether the
> proposition it appears in is supposed to be true. So just the appearance of
> a value--even in context--isn't necessarily data. The appearance of a value
> in a context that is supposed to be true is data.

Are you proposing then that if ¬P(a, b), then a and b are not data at all?

A concern that jumps into my mind generally about all this (in terms of defining 'data') is that yours a's and b's are individuals, not values. I would never consider individuals (people for example) to be data. But I would consider statements about those individuals to be data. All best, J.

>
> It follows then that even though a datum can appear multiple times in the
> same proposition, it is always still the same datum, but that each
> appearance is in addition different data, a predication.
>
> > What one /calls/ that extra component is debatable (context,
> > description, etc), but I cannot see anyway around the above logic - in
> > fact I feel like it is an incredibly strong argument. It starts with
> > agreed observations, followed by the application of the law of
> > indiscernibility of identicals.
>
> > If you can see a hole in it then I'm sure you'll let me know ;)
>
> >> [snip]
> >> > Well put. I contend that you can't do this, and that a poem or image
> >> > as described is not an example of data, but merely values. You are
> >> > saying to me "a poem is data. It is clearly not a fact. Ergo, pwnage."
>
> >> In this discussion I would prefer to actually say "the appearance of a
> >> poem is data".
>
> >> > But you are already assuming it is data in the first step. I say its
> >> > not, and cannot follow why you would think it is. Like a "22". That's
> >> > not data but, if I was a numerologist say, I would still find the
> >> > value interesting.
>
> >> I keep thinking you're ignoring my qualification that it is the
> >> appearance of a value that counts as data, not the value itself.
>
> > Not my intention to ignore it, but I have been wary of getting into a
> > more handwavy discussion about nominalism, universals, formalism etc,
> > etc. However, I hope to have shown above that saying data is the
> > merely appearance of a value (and that may well be part of it) is
> > insufficient, and that a datum is made up of the 'appearance of
> > values' /plus/ something else.
>
> >> > So to me the poem is just a value.
>
> >> Yes, but would you say the appearance of a value is just a value?
>
> >> > Its only data when I say this thing
> >> > here, X, has role Y.
>
> >> We agree that a value doesn't have a context. However the appearance
> >> of a value *does* have a context.
>
> > Ok, I understand. I am just saying the context has to be considered as
> > part of the data, not just as a product of it appearing. Again, I
> > hope my previous logic has shown that the data must be considered as
> > possessing an attribute outside of 'a value' and the fact that it
> > appears.
>
> >> > A picture is just a picture. Even if its, say, a
> >> > biochemistry picture of a cell membrane. _However_ if that picture is
> >> > then put in a log book, under "image of neurostem cell from experiment
> >> > B", its data. This accords to tradtional definitions.
>
> >> You seem to have three distinct arguments.
>
> >> 1) Data requires knowledge in order to decode it as a value; and
> >> this knowledge is part of the data.
>
> >> 2) David has been saying data = value; and
> >> a value (is just a value and) doesn't have a context; and
> >> a conveyed value without a context is meaningless.
>
> >> 3) by definition data = encoded values that represent facts; so
> >> an encoded poem (with no additional context) is not data
>
> >> Please tell me if I've misrepresented you!
>
> > Hard to tell, I think I've gradually been changing my mind throughout
> > this conversation ;) I certainly feel like I have a stronger argument
> > now to explain what was more of an intuition to begin with. But hey, I
> > try not to be too prissy about this sort of stuff, as I find that I
> > learn more that way.
>
> > My whole argument appears to be now be that you can't externalize the
> > context bit, so I'll leave it at that. Regards, Jim.
>
> >> I would say (1) doesn't actually lead to any differences in practise
> >> over what we call data, making it appear rather metaphysical.
>
> >> In my opinion (2) can be defeated for two different reasons
> >> a) David has actually been saying data = appearance of value; and
> >> an appearance of a value has a context
> >> b) there exists examples (like a poem) where a conveyed value
> >> without any
> >> additional context is useful.
>
> >> (3) leads to a difference on real examples, but I do find it
> >> surprising that I could give you a disk with a web page encoded on it
> >> and you would claim that it isn't actually data (but it may contain
> >> data).
>
> >> > I am offering you examples where you have an item that you would not
> >> > describe as data, and showing how it is turned into something that is
> >> > generally described as data. All best, have found the conversation so
> >> > far well articulated, even if we don't agree.... Jim.
>
> >> Also the conversation has been courteous. Cheers!
Received on Mon Feb 18 2008 - 18:00:23 CET