Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation
Date: Thu, 03 May 2007 12:44:04 GMT
Message-ID: <oOk_h.157495$aG1.144120_at_pd7urf3no>
Jon Heggland wrote:
> paul c wrote:
>
>>Jon Heggland wrote: >> >>>I think this is oversimplifying. Constraints are associated with >>>variables, so we need the variables for something more than value >>>aliases. >>>... >> >>Hadn't thought of that, perhaps it is so, I'm not sure yet. Still >>thinking of a constraint as an expression that produces a value from one >>or more others.
>
>
> A constraint is a boolean-valued expression, yes. But expressed in terms
> of variables---otherwise it would be a proposition, and not all that useful.
>
> I don't think we disagree all that much. But the concept of "variable"
> is very simple, and very familiar. I think your talk about language
> devices and relations having one value is confusing rather than
> clarifying. Consider this:
>
> 'Integer variables are nothing more a language device, for talking about
> integers, whether the language is Java or English. They merely serve to
> save us specifying an integer everytime we refer to it. The name of an
> integer variable stands for a given integer in a given conversation.
> All assignment does is allow one to replace one integer with another. A
> given integer has one value now and forever. Someone realized that such
> names could be used to stand for different integer values at different
> times, ie., the values of different integers that happen to have the
> same characteristics. I think it's okay to talk about mutations and
> such when one is talking about a programming language but there is no
> such notion when one is talking about integers. Maybe that someone
> opened the door to such myticism when he mentioned "time-varying
> integers". Unfortunate phrase, if you ask me. Words like "state" are
> akin.'
>
> This is obviously a much too convoluted (and imprecise) way of
> explaining integer variables, and relation variables really aren't
> significantly more complicated than those.
Heh heh, you've made that paragraph resemble some programs I've read. (There's a word for that, where a description resembles what it's describing, but I forget it.) I'd be happy with plain variable, ie., variable full-stop.
I like the D&D primes and wonder if they wouldn't be convenient outside of constraints. Not just A', I wouldn't mind A'', say to stand for the value derived from the derivation of A. The reason I like them is that they help me see which value I started with, ie., what place-holders are bound to what values. When looking at many assignments it is easy to get lost trying to figure out what values were substituted. Maybe it would be clearer to call assignment "bind".
Sorry if this seems just as convoluted as the quoted paragraph.
p Received on Thu May 03 2007 - 14:44:04 CEST