Re: No exceptions?
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sat, 01 Jul 2006 23:05:41 GMT
Message-ID: <9dDpg.4806$pu3.112227_at_ursa-nb00s0.nbnet.nb.ca>
>
> empty
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> Well done. However, I would slighlty edit: A definition IS A contract for
> communication.
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>
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> Do you really mean "breech" or did you mean "breach" ?
Date: Sat, 01 Jul 2006 23:05:41 GMT
Message-ID: <9dDpg.4806$pu3.112227_at_ursa-nb00s0.nbnet.nb.ca>
Rich Ryan wrote:
> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message
> news:MTzpg.4709$pu3.109666_at_ursa-nb00s0.nbnet.nb.ca...
>
>>Jon Heggland wrote: >> >>>Bob Badour wrote: >>> >>>>Jon Heggland wrote: >>>> >>>>>"Every attribute" would also be a superkey (speaking loosely). The
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> empty
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>>>>>set is a subset of every set. >>>> >>>>I respectfully suggest the confusion caused by your use of key without >>>>the 'candidate' qualification demonstrates exactly why we have the term. >>>>I suppose irreducible key would do just as well, but for historical >>>>reasons, candidate key already means an irreducible key. >>> >>>I don't think the confusion is on my part. "Key" (as opposed to >>>"superkey") already implies irreducibility; that's the point of the >>>superkey/key distinction. A "candidate key" is certainly irreducible >>>(due to being a key), but "irreducible key" is redundant. >> >>Candidate key, superkey and proper superkey all have different precise >>meanings and all of them are keys. >> >>A definition is like a contract for communication and understanding.
>
> Well done. However, I would slighlty edit: A definition IS A contract for
> communication.
>
>
>>When you arbitrarily redefine key to mean candidate key, you breech that >>contract and the result of that breech is confusion.
>
> Do you really mean "breech" or did you mean "breach" ?
Breach, of course. Received on Sun Jul 02 2006 - 01:05:41 CEST