Re: Proposal: 6NF
From: paul c <toledobythesea_at_oohay.ac>
Date: Thu, 12 Oct 2006 02:07:40 GMT
Message-ID: <MrhXg.124336$5R2.28597_at_pd7urf3no>
>>> On Fri, 06 Oct 2006 08:32:36 GMT, Brian Selzer wrote:
>>>
>>>> "JOG" <jog_at_cs.nott.ac.uk> wrote in message
>>>> news:1159970386.339044.87090_at_i42g2000cwa.googlegroups.com...
>>>>> Brian Selzer wrote:
>>>>>> "JOG" <jog_at_cs.nott.ac.uk> wrote in message
>>>>>> news:1159954091.119164.155490_at_m73g2000cwd.googlegroups.com...
>>>>>>> All of your points represent a wild goose chase in my eyes Brian. A
>>>>>>> proposition with a NULL in it is no proposition at all. From a
>>>>>>> logical
>>>>>>> perspective, case closed. A relation tuple with a NULL in it is no
>>>>>>> relation tuple at all. From a mathematical perspective, case closed.
>>>>>>> Trying to invoke the 'kludge perspective' is hardly going to convince
>>>>>>> a
>>>>>>> theoretical newsgroup.
>>>>>>>
>>>>>> Is the empty set a value? Yes, it is. So why can't a null be?
>>>>> Because an empty set is a value and a NULL is not.
>>>>>
>>>> Why not?
>>> Hi Brian,
>>>
>>> Because relational databases supporting NULL *define* it as a marker
>>> denoting the absence of a value. Dawn actually makes a good point about
>>> context: in C for instance, NULL has a completely different meaning.
>>>
>>> But since this is a discussion about relational databases, I'll assume
>>> the standard definition of NULL for relational databases unless you
>>> specifically state otherwise.
>>>
>>> (snip)
>>>> The empty set /indicates/ the absence of a value, yet it /is/ a value; a
>>>> null /indicates/ the absence of a value, yet it /isn't/ a value? Why the
>>>> double standard?
>>> Wrong. The empty set *IS* a value. It's domain is the domain of sets. A
>>> set is a value that can hold zero, one or more values of a specified
>>> domain. The empty set happens to hold a zero number of values.
Date: Thu, 12 Oct 2006 02:07:40 GMT
Message-ID: <MrhXg.124336$5R2.28597_at_pd7urf3no>
JOG wrote:
> Brian Selzer wrote: >> "Hugo Kornelis" <hugo_at_perFact.REMOVETHIS.info.INVALID> wrote in message >> news:bjidi29k8crgbrh536l9t3et41chha1i1n_at_4ax.com...
>>> On Fri, 06 Oct 2006 08:32:36 GMT, Brian Selzer wrote:
>>>
>>>> "JOG" <jog_at_cs.nott.ac.uk> wrote in message
>>>> news:1159970386.339044.87090_at_i42g2000cwa.googlegroups.com...
>>>>> Brian Selzer wrote:
>>>>>> "JOG" <jog_at_cs.nott.ac.uk> wrote in message
>>>>>> news:1159954091.119164.155490_at_m73g2000cwd.googlegroups.com...
>>>>>>> All of your points represent a wild goose chase in my eyes Brian. A
>>>>>>> proposition with a NULL in it is no proposition at all. From a
>>>>>>> logical
>>>>>>> perspective, case closed. A relation tuple with a NULL in it is no
>>>>>>> relation tuple at all. From a mathematical perspective, case closed.
>>>>>>> Trying to invoke the 'kludge perspective' is hardly going to convince
>>>>>>> a
>>>>>>> theoretical newsgroup.
>>>>>>>
>>>>>> Is the empty set a value? Yes, it is. So why can't a null be?
>>>>> Because an empty set is a value and a NULL is not.
>>>>>
>>>> Why not?
>>> Hi Brian,
>>>
>>> Because relational databases supporting NULL *define* it as a marker
>>> denoting the absence of a value. Dawn actually makes a good point about
>>> context: in C for instance, NULL has a completely different meaning.
>>>
>>> But since this is a discussion about relational databases, I'll assume
>>> the standard definition of NULL for relational databases unless you
>>> specifically state otherwise.
>>>
>>> (snip)
>>>> The empty set /indicates/ the absence of a value, yet it /is/ a value; a
>>>> null /indicates/ the absence of a value, yet it /isn't/ a value? Why the
>>>> double standard?
>>> Wrong. The empty set *IS* a value. It's domain is the domain of sets. A
>>> set is a value that can hold zero, one or more values of a specified
>>> domain. The empty set happens to hold a zero number of values.
>> Hi, Hugo. >> >> I believe I said that the empty set *IS* a value. It's abstract, but it is >> a value. The set of all sets does not exist; therefore, the domain of sets >> does not exist. Consequently, the empty set does not have a domain. It has >> an abstract type, however. > > This argument and conclusion is maddening. The set of sets does not > exist hence the empty set has no domain? ...
Good point.
p Received on Thu Oct 12 2006 - 04:07:40 CEST