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Re: Blank nodes semantics - existential variables?

From: Patrick J Hayes <phayes@ihmc.us>
Date: Mon, 29 Jun 2020 14:31:03 -0500
Message-ID: <21EDD264-4EE3-4B4B-8824-D0BD1358D7A2@ihmc.us>
CC: <semantic-web@w3.org>
To: angin scribe <anginscribe3@gmail.com>


> On Jun 21, 2020, at 8:35 AM, angin scribe <anginscribe3@gmail.com> wrote:
> 
> Hi everyone,
> 
> Is the standard semantics of blank nodes in RDF still the same as existentially quantified variables? 

Yes. See the ’technical note’ in https://www.w3.org/TR/rdf11-mt/#blank-nodes <https://www.w3.org/TR/rdf11-mt/#blank-nodes> 

> Let "_:b1" and "_:b2" be blank nodes, In the current standard semantics of RDF, is it still true that the graph below does not necessarily mean that Bob has two different things?
> 
> Bob has _:b1
> Bob has _:b2
> 
> I.e., two syntactically different blank nodes do not necessarily mean that they are two different entities.

Correct. 
> 
> I know that there has been a lot of discussion on blank nodes in the past, cf. [1, 2, 3]. I just want to make sure that there are no recent changes on the semantics of blank nodes that I missed. Please let me know if I miss some recent updates in this area. Many thanks!

None since RDF 1.1 became a Recommendation.

Pat

> 
> 
> Cheers,
> A
> 
> [1] M. Arenas, M. Consens. A. Mallea. Revisiting Blank Nodes in RDF to Avoid the Semantic Mismatch with SPARQL. https://www.w3.org/2009/12/rdf-ws/papers/ws23 <https://www.w3.org/2009/12/rdf-ws/papers/ws23>
> 
> [2] A. Hogan, M. Arenas, A. Mallea, A. Polleres. Everything You Always Wanted to Know About Blank Nodes. Journal of Web Semantics. 2014.
> 
> [3] A. Mallea, M. Arenas, A. Hogan, A. Polleres. On Blank Nodes. ISWC 2011.
> 


Received on Monday, 29 June 2020 19:31:23 UTC

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