Re: SQL, related records (quotes)

"Stefan Rybacki" <stefan.rybacki_at_gmx.net> wrote in message news:3i80bkFk955oU1_at_individual.net...
> Dan Guntermann wrote:
>> "Stefan Rybacki" <stefan.rybacki_at_gmx.net> wrote in message
>> news:3i78t2Fk4c3tU1_at_individual.net...
>>
>>>Dan Guntermann wrote:
>>>

<snip>
>> Deesn't non-symmetry simply mean there exists a tuple <child X, parent Y>
>> in hierarchies such that there is no corresponding tuple <child Y, parent
>> X> in hierarchies? This isn't the same as a universal quantifier.
>>
>> No. I still think anti-symmetry in conjunction with non-reflexive holds
>> here. Does the following meet the definition of anti-symmetry that you
>> state above?
>
> anti-symmetry + non-reflexifity = non-symmetry

Ahh. I've seen formal definitions for this in terms of assymetric properties. Non-symmetric is new to me and seems awfully close to "not symmetric." It's not worth getting into quibbles over. I'll take your word for it.

• Dan