Re: TMQL: Direct (super|sub)types?

Lars,

On 3/2/2011 7:32 AM, Lars Marius Garshol wrote:
> * Lars Heuer
>> Even if I try to restrain me: What are *direct* supertypes/subtypes?

I assume from what has been said that an "indirect" type would be:

> Consider a type hierarchy like:
>
>    - organization
>      - company
                  - division
>      - foundation
>
Yes?

> Now, let's say you want to find those topics which are explicitly marked in the topic map as instances of "organization", so that you can tell people to turn them into instances of one of the subtypes. (For example.)
>
> Similarly for direct-subtype. Let's say you want to visualize the type hierarchy. If querying for the subtypes of A always returns also indirect subtypes, how are you going to do it?
>

Err, isn't "always returns also indirect subtypes" an implementation 
choice that has to be "fixed" by "direct-subtype?"

There is a declaration of super-type/sub-type for the relationship to 
exist at all.

So what is the difficulty....

Ah, it is a question of what is the default?

OK.

In other words, "sub-type organization" could by *default* return

company,

or

company, division, and foundation.

If the "default" is only company, then need something like sub-type * 
organization, to return all the subtypes of organization.

I would be in favor of the wildcard operator since that is an explicit 
choice to take the hit on getting all the subtypes (I am sure this will 
come up in other cases as well) and it leaves a well-defined default if 
the wildcard is not specified.

> We included 'direct-instance-of' in tolog and are very glad we did, because while it's quite a bit less common than 'instance-of' it's used quite a bit.
>

If it is used more often than obtaining all the subtypes, let's make it 
the default position.

Hope you are having a great day!

Patrick


> --Lars M.
> http://www.garshol.priv.no/tmphoto/
> http://www.garshol.priv.no/blog/
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-- 
Patrick Durusau
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Chair, V1 - US TAG to JTC 1/SC 34
Convener, JTC 1/SC 34/WG 3 (Topic Maps)
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