Re: Temporal database - no end date

On Jan 21, 1:32 pm, "DBMS_Plumber" <paul_geoffrey_br..._at_yahoo.com> wrote:
> NENASHI, Tegiri wrote:
> > I only started to read about the chronon. The articles that I read say
> > that the application defines the granularity of chronon. Some one asked
> > why is it that you cannot utilize the granularity of smaller value, one
> > minute but not one day ? I am interested to know your opinion.
>
> You can.
>
> But regardless of the granularity you select, the problem still
> arises.
>
> Let us introduce a 'chronon' which is the amount of time it takes a
> light quanta to traverse a proton (say). What is the mean value of a
> large number of such measurements? What is the variance? These values
> will include some fraction of a 'chronon' so defined.

So? You've admitted we can speak meaningfully about 2.3 children, and children are indivisible. So what is the issue with speaking of 2.3 chronons?

> > I work on Oracle and I can affirm that the DATE in Oracle is one second
> > of granularity. You say that 0.8 of the quantum is impossible, 0.8 of
> > the day is impossible but 0.8 of 24*3600 is possible. 1/7 of 1000 is not
> > exact (142) but the error is < 0.1 per cent. Why one can not select the
> > granularity of chronon to achieve the exactness ? You can say, go and
> > use floating point, but floating point is not exact too.
>
> The DDL book makes no claims about implementation. Nor should it.
> It's a book that describes a logical model.

You didn't answer the question.

> First, get the logical model right. Then worry about the engineering
> compromises needed by the implementation.
>
> > I read about Snodgrass, and Snodgrass, he uses the name of chronon too.
> > I want to know why you think that the chronon is bad in mathematic sense.
>
> Quanta are not 'bad'. They are not 'good'. The argument I am making
> is merely that 'time quanta' (as described in the DDL book) represent
> an innappropriate model for temporal reasoning because modeling time as
> a continuum and temporal phenomenon using intervals over the continuum
> is more general.

You didn't answer this question either.

Marshall Received on Sun Jan 21 2007 - 22:48:35 CET