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Your first example takes

    <brian> parentOf <bct>
    <brian> name 'Brian'
    <bct> name 'Brendan'
and deduces

    'Brendan' hasParentNamed 'Brian'
How is this substantially different from the second example? Forgive me if I'm thick; I'm honestly trying to understand.

It's not deducing a third property "hasParentNamed".

It's joining the two graphs so that you can do a query like this:

    SELECT ?parentName WHERE
      ?child name 'Brendan'
      ?parent parentOf ?child
      ?parent name ?parentName
to find the name of Brendan's parent.

You're being quite patient with me, thanks. :)

Still not getting it, here's your second example in that syntax:

      <brian> parentOf ?son
      ?son gender <male>
What's the fundamental difference? That one example yields a new RDF triple, and the other yields a query result? Surely this is just a matter of representation.

Good point. I think you've changed my mind about the utility of inferencing :).

The difference between querying and inferencing isn't what I was trying to emphasise, though. My point was the difference between being designed for making queries/inferences within a dataset, and being designed for joining distinct datasets.

Querying within a dataset is easy: SQL, XPath, XQuery, LINQ, etc. You can write rules for transforming any data model that you can query.

RDF isn't anything special in these areas (though I do think that SPARQL is an awfully nice query language). What it gives you is a way to link and merge datasets.

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