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Re: why hierarchy?

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Tue, 01 Aug 2006 01:14:53 GMT
Message-ID: <hWxzg.31431$pu3.418270@ursa-nb00s0.nbnet.nb.ca>


Aloha Kakuikanu wrote:

> Bob Badour wrote:
> 

>>JOG wrote:
>>
>>>Neo wrote:
>>>
>>>
>>>>>how you would represent something like "A person called Bob is friends with a person called Tom" in your system (obviously that's a bidirectional relationship).
>>>>
>>>>(new 'bob 'person)
>>>>(new 'tom 'person)
>>>>(new 'friend 'verb)
>>>>(create bob friend tom)
>>>>(create tom friend bob)
>>>
>>>ok gotcha, good start. Then you have:
>>>
>>>bob --- is_friends_with ---> tom
>>>tom --- is_friends_with ---> bob
>>>
>>>What if I wanted to record a different sentence - "A person called
>>>John is friends with Frank within the remit of Work"? (i.e. they aren't
>>>friends outside of workhours)
>>
>>A better question would be to ask if the requirements change and one
>>needs to record when the friendship began, how does dbd record the bob
>>and tom have been friends since October 12, 1993 ?
>>
>>One of course has to record that fact to answer questions like: What is
>>the average duration of current friendships? What percentage of
>>friendships last more than 15 years? Who began a friendship on October
>>12, 1993 ? etc.
> 
> new 'ternaryRelation
> (new 'john 'person)
> (new 'frank 'person)
> (new '10/12/1993 'date)
> (create  'ternaryRelation john frank 10/12/1993)
> 
> Rather obvious, isn't it?

And how does one write the queries I mentioned? Received on Mon Jul 31 2006 - 20:14:53 CDT

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