# Re: NULLs: theoretical problems?

Date: Mon, 27 Aug 2007 09:00:36 -0000

Message-ID: <1188205236.452964.210980_at_22g2000hsm.googlegroups.com>

On 27 aug, 05:26, "V.J. Kumar" <vjkm..._at_gmail.com> wrote:

*> Jan Hidders wrote:
**> > On 25 aug, 16:32, "V.J. Kumar"
*

> > > Clearly, 'def(x):(x or not x') is allowed [...]

*>
**> > ... and is indeed equivalent with 'def(x):true'.
**>
**> According to your own definition, 'def(x) : f(x)' evaluates to 'false'
**> whenever x is not defined. So f(x) in 'f(x) = x or not x' must be
**> 'false'.
*

I really have no idea why you think that.

*> > > Likewise, 'def(x):(x or true)'
**>
*

> > ... and is indeed equivalent with 'def(x):true'.

*>
**> This is interesting. Just a little while ago, you complimented Jon
**> for his understanding that 'select * from table where def(x): (x or
**> true)' is equivalent to 'select * from table where x is not null and
**> (x or true) '. Apparently, at the time you thought that 'def(x) :(x
**> or true) ' should evaluate to 'false'. It seems that now you think
**> that it should evaluate to 'true' !
*

Not really. The formula 'def(x) : true' does not evaluate to true if x is undefined.

- Jan Hidders