Re: Motion P1788/M0032.02: I vote NO
P1788
On 16 Apr 2012, at 04:49, Michel Hack wrote:
> I vote NO on M0032.02 -- the main issue for me being that the Level 2
> midpoint might not be a member...
>
> Some of these difficulties might be cleared up if we firm up what counts as
> a legitimate number format and a legitimate interval format. For example,
> must we support off-center intervals [a+b,a+c] with b and c of the same sign?
On this last Q, I would say No, why should we, seeing what troubles they seem to cause? I would support the kind of restrictions on number format that Vincent, Dmitry and others are proposing.
Dmitry's idea "every nonempty interval of any type must contain a singleton interval of the same type" is different, being a restriction on interval types T rather than on number formats. I'm a bit dubious, because (a) it may be quite tricky to check for a given proposed T, (b) if you treat the singletons as defining a number format F=myFormat(T), it may be tricky for it to interoperate with ordinary FP formsts. However, both those are really the problem of whoever invents T, not of 1788, so I could be convinced.
John Pryce