Re: why hierarchy?
Date: Mon, 31 Jul 2006 20:33:32 GMT
> 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.
>>OR >> >>(new 'bob 'person) >>(new 'tom 'person) >>(new 'friend 'verb) >>(create friend vbType symmetric) >>(createWRR bob friend tom) >> >>OR ... >> >>See old thread titled "Demo: Modelling Cost of Travel Paths Between >>Towns" and related example www.dbfordummies.com/Example/Ex136.aspReceived on Mon Jul 31 2006 - 22:33:32 CEST