Some questions

[Larry Watanabe]

Ron Daniel writes:
>RDF does not leave this important information implicit. Each
>RDF statement has exactly three parts:
>   Subject - the thing being talked about (the documents in
>     the example above).
>   Predicate - the type of statement being made about the subject
>     (author in this example)
>  Object - the value portion of the statement (the author name
>     in this example).

>If the data was expressed in RDF, an RDF-aware grep-like
>tool would let you select all the RDF properties labeled
>"author", get the URIs of the resource and the name of the
>author, and plop that info into the database. There would
>be no ambiguity about the thing which was authored.

This works fine for inherently binary relations, but for n-ary relations you
end up reifying them by introducing a dummy node. Matching against that
dummy node will yield no matches, or only incorrect ones, since the names of
the nodes are supposed to be new constants (or existentially quantified
variables). 

To make that dummy node meaningful, you would have to match a wildcard
against it and other relations. But then you're back to your original
sitatuation of not knowing what the relation means unless you have further
knowledge of the semantics of the relations.

-Larry Watanabe
Jetform Corporation
lwatanab at jetform.com


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