Entity sets - containment and parent-child

[Mark Beall]

On Nov 12, 2009, at 12:06 PM, Jason Kraftcheck wrote:

> Mark Beall wrote:
>>
>> So the only substantial difference between the containment and
>> parent-child relationship is that I can ask for the parents of an  
>> entity
>> set in a parent-child relationship whereas I can't in a containment
>> relationship (although the ability to do that would be easy enough to
>> add).
>
> How easy it is to add would depend on the implementation.
>
>> In the containment relationship, the contained sets do play a part
>> in the entity set operations, but it would be trivial to ignore  
>> them in
>> the results.
>>
>
> I'm not sure what you mean.  The contained sets take part in things  
> like
> boolean operations.  The effect such operations have on contained  
> sets would
> be reflected in the output of getNumEntSets, getEntSets and  
> isEntSetContained.

Yes, but the entity sets only take part in the boolean operations with  
other entity sets, so there are really two boolean operations going on  
at once (one with the entities in the set and one with the entity sets  
in the set), so if I don't look at the entity sets in the result, it  
doesn't matter if they are there or not.

I'd be interested in knowing the various use cases for using entity  
set containment vs. a parent-child relationship. It seems to me that  
they are just about identical, so I'm curious when one would use one  
vs. the other.

mark