On Fri, Jun 22, 2007 at 07:38:01PM +0300, Tzahi Fadida wrote:
> Let me simplify it in lamer terms.
> Basically, you have a cycle in your relations schema. i.e. 
> rel A: att-x, att-y
> rel B: att-y, att-z
> rel C: att-z, att-x
> 
> The only way to join these three without loosing a lot of information (aside 
> from some very weird corner cases which i won't mention here), is to use my 
> full disjunctions which is probably most certainly the only implementation of 
> the operation in existence to calculate the general case (which you can see 
> above).

FWIW, with this simple description I finally worked out what full
disjunctions are and why you can't do them (efficiently) in SQL.

Have a nice day,
-- 
Martijn van Oosterhout   <[EMAIL PROTECTED]>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to 
> litigate.

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