Re: So what's null then if it's not nothing?

From: Frank Hamersley <terabitemightbe_at_bigpond.com>
Date: Wed, 07 Dec 2005 14:24:52 GMT
Message-ID: <UgClf.13909$ea6.6355@news-server.bigpond.net.au>

Jon Heggland wrote:
> In article <1133894046.516473.27860_at_f14g2000cwb.googlegroups.com>,
> boston103_at_hotmail.com says...
>

>>>>>What do you call the domain { TRUE, UNKNOWN, FALSE }? And by the way,
>>>>>haven't you argued for ages that names don't matter?
>>>>
>>>>Names do not matter,  but the number of logical constants does.  If
>>>>it's more than two,  then the logic is most certainly not Boolean.
>>>
>>>You are quibbling.
>>
>>I beg your pardon ?  The number of logical constants,  not thir names,
>>is what distinguishes propositional logic from various multivalued
>>logics,  including various breeds of 3VLs.

>
> You don't answer my questions; you come up with complete non sequiturs.
> A domain has a name. The domain consisting of the values { TRUE, FALSE }
> is called Boolean. There is another domain, consisting of the values {
> TRUE, UNKNOWN, FALSE }, which I called "3VL Boolean".

The trouble with your definition is that it is nonsensical - more than a bit like what Alice encountered!

The root problem is that the "UNKNOWN" (aka NULL) itself is not and never will be a member of that or any other domain. Accordingly others have called is a "Special" value.

When the attribute value does become known (lets say it is "MAYBE") then it is no longer UNKNOWN, it is MAYBE and it is a member of the domain (YES, NO, MAYBE) (sic) :-)

[..]

Personally I don't understand why NULL is so hard "to get". But then there are lots in IT who don't get it so I should expect this thread will rise again in about a years time (assuming it has died in the intervening period).

Frank. Received on Wed Dec 07 2005 - 08:24:52 CST