Re: a blank node issue

Ivan Shmakov wrote:
>>>>>> Pat Hayes <> writes:
> […]
>  > But before you label this an "issue", let me turn the scenario
>  > around.
> […]
>  > Now serialize these "identical" graphs into two identical
>  > serializations and send them to a common source and ask it to
>  > deserialize them into a single graph. Should it merge these blank
>  > nodes into one? It may well be that if more information had been
>  > sent, it would have been clear that these were two different
>  > people. But even if not, it is clear that can be no general warrant
>  > to presume that two different blank nodes must co-refer, unless of
>  > course one knows that the provenance of the information guarantees
>  > that they do.
>  Actually, the question I'm concerned with is exactly the
>  opposite one: is there any practical necessity to /preserve/
>  blank node identity when used /as an object/?
>  To repeat myself, while serializing subgraphs, it's easy, given
>  the current standards and implementations, to “break” the
>  following graph:
> foo bar _:blank .
> baz qux _:blank .
>  into the one where the subjects of the triples aren't the same:
> foo bar _:blank1 .
> baz qux _:blank2 .
>  (Though the respective descriptions of the blank nodes are the
>  same.)
>  Now, I wonder, what would be the negative consequences in
>  practice should we assume that such a “breakage” is not an
>  exception, but a rule.  Or, in other words, that the blank node
>  identity /as an object/ is of no semantic value.
>  Immediately, it becomes possible:
>  • to re-create any graph from the set of concise bounded
>    descriptions [1] of its respective (non-blank) subjects;
>  • to assign each blank node a content-based identifier (e. g.,
>           as per [2].)

Hmm, I'm confused - Blank Node Identifiers are purely a property of the 
serializations, and not of the blank node, the blank node does not have 
an identifier, rather the serializations use a temporary identifier so 
that a blank node can be recomposed when you deserialize. As in, it's 
already the case that blank node identity has no semantic value, because 
blank nodes don't have an identifier.



Received on Tuesday, 1 March 2011 19:42:45 UTC