- From: Thomas Passin <tpassin@tompassin.net>
- Date: Thu, 22 Nov 2018 22:16:47 -0500
- To: semantic-web@w3.org
On 11/22/2018 6:49 PM, David Booth wrote: > Uh . . . I don't think that is quite correct. As I understand, a blank > node does *not* represent *a* thing. Rather, it asserts that there > *exists* a thing, as explained in the RDF Semantics: > https://www.w3.org/TR/rdf11-mt/#blank-nodes > In contrast, an IRI represents *a* thing. I'm sorry to be pedantic > here, but I mention it because it underscores my point: the semantics of > blank nodes really *are* subtle -- at least to *average* developers. Again, blank nodes are exactly analogous to a table with no primary key. You can identify the thing by the union of its properties ... until there is another thing with the same set of properties. Then you would need to have another property to distinguish the two, which property you might or might not know. You can't have a foreign key, but you can still have a WHERE statement that specifies all the properties that could distinguish the data object. And just as with relational databases, the no-primary-key model can only get you so far. But it can be an easy way to get a data set going...
Received on Friday, 23 November 2018 03:17:17 UTC