Re: Disjoint, subset, & interior, or more...???
On 2010-10-03 15:54:22 -0700, Dan Zuras Intervals wrote:
> And what better way to convince them that it is a mistake
> than to hit them right away with the fact that you cannot
> compare two intervals as you once compared two floating-
> point values? [...]
I'm not sure what you mean here, but I'd see that more a problem
with languages and the chosen bindings. Whatever we decide here,
a language would still have the choice to bind <= to some interval
operation or not (whether it is a primitive or not).
[...]
> But, are there never interval methods which need to know
> whether or not two intervals are ordered by less than?
> At least to know that all elements of one interval are
> less than any element of another? That is, strict &
> disjoint less than.
>
> It seems to me, at the very least, we must consider that
> intervals are ordered by strict less than or not. The
> various overlapping forms of less than may or may not be
> important but this one seems to be clearly so.
I agree.
[...]
> So I can argue for these 4 comparisons: disjoint, subset,
> equal, & strict less than.
I also think that "disjoint" is important as it allows to check that
two values (represented by intervals) are necessarily different.
"subset" allows to check whether some value (represented by an
interval) belongs to an interval.
I have no idea about "equal". Note that if NaI is seen as the empty set
with a decoration, NaI = NaI can be confusing.
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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