On 5/30/13 11:40 PM, John F Sowa wrote:
>> >I stay away from blank nodes for these kinds of presentations.
>> >Basically, blank nodes and reification serve important purposes
>> >that are only appreciated if comprehension is established.
> Since I emphasize the mapping to and from controlled English,
> an existential quantifier (or blank node) is very easy to explain.
> It's just a reference to something by saying "a cat" instead of
> saying "the cat Yojo".
> If you know that Tom and Sue are siblings, you know that they
> have at least one common parent. But you don't know the identity.
> So you need an existential quantifier (or a blank node in RDF). (01)
I agree, but I tend to use the function of the pronoun (noun and noun
phrase substitution) in natural language grammar to exemplify the blank
node function. I also use examples scenarios where full identity isn't
required in social relationship settings: (02)
1. family vacation and parents would like the kids to meet up with their
peers -- the hotel or party planners only need to know the ages and
gender as opposed to complete details
2. data access policies -- here one is able to grant resource access
based on relations that don't necessarily expose the identities of
relation objects or subjects etc.. (03)
Blank nodes and statement reification are powerful concepts that have
been maligned (in the RDF realm) due to poor understanding their utility
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