Re: Discussion paper: what are the level 2 datums?
On 2010-10-09 12:41:42 +0200, Arnold Neumaier wrote:
> The only reasonable alternative I can see (but do not propose to use)
> is the treatment of Empty, where (at the expence of more complex
> executing formulas) one could sensibly argue to take
> inf(Empty)=+inf, sup(Empty)=+inf, mid(Empty)=0, rad(Empty)=-inf
> in place of NaN for all four results.
I suppose you meant sup(Empty)=-inf.
Concerning mid(Empty), I don't like 0, because it would be an
arbitrary choice (just like +inf + -inf is not 0). IMHO it should
be undefined at Level 1 and NaN at Level 2.
Concernant rad(Empty), -inf makes sense if we regard rad(x) as
(sup(x) - inf(x)) / 2. But NaN would be fine too.
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Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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