Re: Temporal database - no end date

"Marshall" <marshall.spight_at_gmail.com> wrote in news:1169571062.360638.112650_at_a75g2000cwd.googlegroups.com:  

> Anyone have a good pointer to a definition of conceptual,
> logical, physical?

The real numbers are defined with axioms like a certain ordered field. All the constructions that conform the axioms are real numbers. Two commonest constructions are realized with Dedekind cuts and the sequences of Cauchy.

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>> My point is only that it's the underlying logical model of the reals
>> that allows us to make sense of what floating point numbers are all
>> about.

The floating point numbers are a finite very tiny subset of the rational numbers but one cannot say they are the 'true' rational numbers because they are not closed like the rational numbers. Their operations are bizarre because of the problems of rounding and precision. The floating numbers are coded with two varying integers, the mantissa and the exponent and one permanent integer, the base.

There is a very nice Web article on the Java floating numbers: http://blogs.sun.com/darcy/resource/J1_2003-TS-2281.pdf

One can not model the continuum with the floating numbers because they are discrete and finite like the computer integers.

--
Tegi



> 

> Again, the phrasing is odd to me, but yeah, definitely.


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> Marshall

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> PS. I would have replied sooner, but you know, Heroes was on.

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