Re: two nasty schemata, union types and surrogate keys

Brian wrote:

>Under the closed world intepretation, every formula that can be
>represented in a table is assigned a truth value--positive for those
>that are actually represented in the table and negative for those that
>aren't, but under the open world interpretation, only those that are
>actually represented are assigned truth values. Let's put it another
>way: either it is supposed to be true or it is known to be true.
>Under the closed world interpretation, what is represented is supposed
>to be true, but under the open world interpretation, what is
>represented is known to be true. Bottom line: it would be pointless
>to suppose that what is represented is known to be true.

I can't link this to the notion of closed world assumption I'm familiar with. It doesn't make sense to me.

-- 
Reinier