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From: Mikkel Meyer Andersen <mikl@mikl.dk>
Date: Mon, 3 Jan 2011 19:41:19 +0100
Message-ID: <AANLkTik5z44BoQD5NTFn0Cq-BoD8Vx+Y70wEiCgVXkLe@mail.gmail.com>
Subject: Re: [math] meaning of "support" in distributions classes
To: Commons Developers List <dev@commons.apache.org>
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2011/1/3 Phil Steitz <phil.steitz@gmail.com>:
> On Mon, Jan 3, 2011 at 2:23 AM, Mikkel Meyer Andersen <mikl@mikl.dk> wrot=
e:
>
>> 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 close=
d,
>> hence the corresponding isInclusive-functions can be discussed. I though=
t
>> about it being useful for infinity, but we could let users deal with thi=
s
>> themselves?
>>
>
> Yeah, sorry I missed this before. =A0It hit me when I was =A0working on t=
he 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). =A0I dropped the
> inclusive/exclusive functions there. =A0I think in the discrete case, thi=
s can
> be handled by convention and the only issue there is the same as the
> continuous one - infinities - but these are all the same. =A0So I propose=
 that
> we drop these functions in 3.0 as well. =A0The isSupportConnected propert=
y
> still logically makes sense; though it is always true for the 2_X
> distributions, so I dropped it there.
+1
I agree. For now we don't need them, neither in 2.2 nor 3.0. Is there
any sense in keeping them if we later on includes distributions where
it would be beneficial to have such functions, or should we simply
just add them then?
>
> 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 distributio=
n
>> > anywhere. I have been assuming that we mean the smallest closed set su=
ch
>> > that its complement has probability 0. This would make, for example, t=
he
>> > 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 discre=
te
>> > case?
>> >
>> > Phil
>>
>

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