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Re: Motion 52: final "Expressions" text for vote



Bill,

That has already been proposed, discussed, and decided.  The
results can be deduced from the decision that intervals are
subsets of the real numbers, as well as from the decoration.
(The decoration takes care of the fact that, in some contexts,
evaluation of a function over an interval partially in and
partially out of a domain makes sense, whereas in other
contexts, it does not.)

Baker

On 11/23/2013 05:04 PM, G. William (Bill) Walster wrote:
On 11/23/13 1:07 PM, Kreinovich, Vladik wrote:
We have gone through these questions when we started the standard.

The range of a function over the interval is defined as the set of all possible values of the function when its arguments are in the range. If for some values within the range, the function is not defined, there are no values to add to the set.
Do you mean instead of the above:

The range of a function over the interval is defined as the set of all possible values of the function when its arguments are in the*function's domain of definition*.*

That is:

	f(X) = { f(x) | x \in X \cap D_f };

where X is an interval and D_f is f's domain of definition.

Therefore, the interval extension of any function returns the empty set { } for any argument outside the function's domain of definition.

*

In this case, the containment set of 1 / [0, 0] is { }, the empty set.

Is this what you propose?

If so, then I claim this is a containment failure because in the
projective real system 1/0 = oo, which is not the empty set. Therefore
there is an inconsistency in the proposed theory.

Cheers,

Bill



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R. Baker Kearfott,    rbk@xxxxxxxxxxxxx   (337) 482-5346 (fax)
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Department of Mathematics, University of Louisiana at Lafayette
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