# Re: All hail Neo!

Date: Sun, 23 Apr 2006 13:58:14 GMT
Message-ID: <WJL2g.64598\$VV4.1223196_at_ursa-nb00s0.nbnet.nb.ca>

Frank Hamersley wrote:

```>> Frank Hamersley wrote:
>>
```

>
> [..]
>
```>>>> In that line of thought, here's an interesting question that Date et
>>>> al have posed before to the n-VL folks:
>>>>
>>>> If "exists but empty" is true and "doesn't exist" is false, what is
>>>> null?
>>>
>>> Neither and both!
>>
>> I find that sort of handwaving to be a complete non-answer.
```

>
> I suspect you are wearing the darkly tinted glasses of preconception.
> Whilst I was trying to show a little wit, the current 3VL state of
> affairs still seems to me to fit that description.
>
```>> A much more intellectually honest reply would be: "I don't know."
```

>
> Not from this black duck (on this occasion)!
>
```>> or "Null has no similar analog in set theory."
```

>
> I wasn't comparing/contrasting the RM with set theory. Perhaps for you
> it is implicit?

No, it is quite explicit. Relations are sets. Relational algebra is the equivalent of set theory, and relational calculus is the equivalent of predicate calculus.

```>> True and 1 both have the exact same analog in set theory. False and 0
```

>
> Perhaps but insistence on a parallel form for the RM does not seem to
```>> This has a certain elegance and symmetry.
```

>
> I agree that and readily subscribe to that in my own endeavours.
>
```>> In canonical form:
>>
>> {} = 0 = false
>> {{}} = 1 = true
>>
>> What is the similar analog for null?
```

>
> My prior knowledge of your/the notation is non existent but I can prolly
> deduce its intent. So having a stab at it how about ...
>
> {}{} = null

> As an aside (and with no malice aforethought) I am curious why the 0 and
> 1 figure at all? Forced to conform I would probably go with ...
>
> {}{} = -1 = null

http://en.wikipedia.org/wiki/Formalism#Mathematics

"Complete formalisation is in fact in the domain rather of computer science."

And finally, the relational model is itself a formal system:

> * (for another post perhaps) I don't see any great leap forward in the
> aspects of TTM that address the extinction of nulls.

If nulls cause great damange without serving any particularly useful purpose, why should one address their extinction? Received on Sun Apr 23 2006 - 15:58:14 CEST

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