Re: Value
Date: Sat, 23 Feb 2008 22:29:05 +0100
Message-ID: <47c08f6a$0$14354$e4fe514c_at_news.xs4all.nl>
Dmitry A. Kazakov wrote:
> mAsterdam wrote:
>> Dmitry A. Kazakov wrote: >>> "Value" in this context is a CS term. >> I am currently trying to find a helpful piece of text for the cdt >> glossary. >> From what I read at >> http://en.wikipedia.org/wiki/Value_%28computer_science%29 , >> Value looks like a rather controversial CS term.
>
> I don't see it controversial.
You must have not yet read
http://en.wikipedia.org/wiki/Talk:Value_%28computer_science%29
> I understand why you might dislike it.
The definiens starts with "a sequence of bits". This excludes analog computers. I do think 'value' has meaning, within informatics outside the very limited context the wikipedia page currently adopts to define it.
Is this your understanding? Clever! ;-)
> I support it for the same reason:
> it clearly, though maybe clumsy, states that 1 integer is not 1 float.
That is a (so ISTM) misguided attempt to hide the concept of 'value' behind Type. What is Type IYO?
>> Do you have a better reference?
>
> You mean one, that would support claims of DB-folks? (:-))
> -------------
> Honestly, I wonder how one could define values otherwise
> while preserving types.
Ah, ok.
> Let me elaborate it a bit informally. The idea of type in
> mathematics was introduced to get rid of antinomies. In CS it is the same
> idea with antinomies extended to the cases of incomputability. We cannot
> judge about equivalences of entities. It could turn undecidable or simply
> too expensive.
> We define entities being values with a
> type assigned to them, merely in order to be able to distinguish them
> *without* computing P(v1=v2). That's the whole idea. Therefore if a v1 is
> of the circle type and v2 is of the ellipse type, that makes them
> automatically distinct. Just *per* construction. This has nothing to do
> with geometry. It is CS.
> Now, when applied to geometry one could reasonably wish v1 and v2
> interchangeable in some contexts. That is called substitutability. Note
> that substitutability assumes that you substitute *one* thing for
> *another*.
> So these are *different* things. Substitutability of circle for
> ellipse is a CS model of circles being a subset of ellipses. Note, just a
> model of. No physical subsets involved, though not excluded, when for
> example, circle would inherit the representation of ellipse. Moreover any
> such model is necessary inadequate as a trivial Circle/Ellipse analysis
> shows. So, why all this rant?
>
> Just one final stab. Observe that this framework does not exclude
> "physical" subsets. Neither it specifies the sets where values come from.
> This automatically makes it more general than any other model based on
> subsets of values. Whatever you could do on that basis is already included.
No shapes, no data, no value - three victims already. What's the next concept we'll have to ditch avoiding antinomies? Received on Sat Feb 23 2008 - 22:29:05 CET