Re: Blank Nodes Re: Toward easier RDF: a proposal

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:
> 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