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From Phil Steitz <phil.ste...@gmail.com>
Subject Re: [math] meaning of "support" in distributions classes
Date Mon, 03 Jan 2011 16:52:13 GMT
On Mon, Jan 3, 2011 at 2:23 AM, Mikkel Meyer Andersen <mikl@mikl.dk> wrote:

> Hi,
>
> You're right, Phil. Support for beta is [0, 1] and not (0, 1) as stated on
> Wikipedia. As you mention, support for continuous distributions is closed,
> hence the corresponding isInclusive-functions can be discussed. I thought
> about it being useful for infinity, but we could let users deal with this
> themselves?
>

Yeah, sorry I missed this before.  It hit me when I was  working on the 2_X
retrofit and it looked like Beta was wrong (I see now Wikipedia seems to be
using some other definition - or is just wrong).  I dropped the
inclusive/exclusive functions there.  I think in the discrete case, this can
be handled by convention and the only issue there is the same as the
continuous one - infinities - but these are all the same.  So I propose that
we drop these functions in 3.0 as well.  The isSupportConnected property
still logically makes sense; though it is always true for the 2_X
distributions, so I dropped it there.

Phil

>
> Cheers, Mikkel.
> Den 02/01/2011 23.05 skrev "Phil Steitz" <phil.steitz@gmail.com>:
> > We don't precisely define what we mean by the support of a distribution
> > anywhere. I have been assuming that we mean the smallest closed set such
> > that its complement has probability 0. This would make, for example, the
> > support of the Beta distribution [0, 1] independent of the parameters.
> But
> > then isSupportLowerBoundInclusive currently returns false for Beta. I
> must
> > have one of the concepts wrong. Could it be that the
> > upper/lowerboundInclusive attributes are only meaningful in the discrete
> > case?
> >
> > Phil
>

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