W3C home > Mailing lists > Public > semantic-web@w3.org > November 2018

Re: Blank nodes as predicates Re: Blank Nodes Re: Toward easier RDF: a proposal

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 22 Nov 2018 15:00:20 -0600
To: Dan Brickley <danbri@danbri.org>, Martynas Jusevičius <martynas@atomgraph.com>
Cc: martige@ifi.uio.no, Semantic Web <semantic-web@w3.org>
Message-ID: <da088925-23b3-f200-d594-57adb5eedd91@ihmc.us>
On 11/22/18 9:30 AM, Dan Brickley wrote:> This did crop up in 
json-ld, see
 > https://github.com/w3c/json-ld-syntax/issues/37 with the notion
 > of "generalized rdf" introduced in the last round of specs.
 > https://www.w3.org/TR/rdf11-concepts/#section-generalized-rdf
 >
 >
 >
 >
 > On Thu, 22 Nov 2018, 06:20 Martynas Jusevičius
 > <martynas@atomgraph.com <mailto:martynas@atomgraph.com> wrote:
 >
 >     Is that really an essential problem? With blank nodes as
 >     predicates,
 >     will it suddenly become easier to build RDF applications and
 >     explain
 >     it "for dummies"?
 >
 >     A lot of infrastructure will break and/or will have to be
 >     updated,
 >     that is for sure.

FWIW, allowing bnodes in predicate position (and literals in 
subject position) does not affect the RDF semantics at all. The 
2014 RDF 1.1 semantics specification applies to generalized RDF 
syntax without changing a single word.

Infrastructure which checks for conformance to RDF syntax would 
need to be changed, obviously, but the changes should be minimal 
as they simply amount to not performing certain syntax checks 
which are currently required.

Inference engines which perform any kind of unification should 
generalize to the more liberal syntax with minimal changes to 
code, although indexing and hashing might need more substantial 
changes. But any RDF inference engine which is complete will 
probably be already using generalized RDF syntax, or something 
equivalent, internally.

Basically, it would be a lot easier than many people think.

Pat Hayes

 >     <martige@ifi.uio.no <mailto:martige@ifi.uio.no>> wrote:
 >      >
 >      > On 22/11/18 13:02, Tim Berners-Lee wrote:
 >      > >> On 2018-11 -21, at 22:40, David Booth wrote:
 >      >
 >      > >> Blank nodes are special second-class citizens
 >      > >> in RDF.  They cannot be used as predicates,
 >      > >
 >      > > Agreed it messes up the symmetry.  Actually in most of
 >     my code you can
 >      > > use a blank node as a predicate.  That said, RDF is
 >     unusual in having as
 >      > > much symmetry.
 >      >
 >      > I like symmetry. Can we get a ✅ for blank nodes as
 >     predicates too?

✅

 >      >
 >      > Martin
 >      >
 >
-- 
-----------------------------------
call or text to 850 291 0667
www.ihmc.us/groups/phayes/
www.facebook.com/the.pat.hayes
Received on Thursday, 22 November 2018 21:00:56 UTC

This archive was generated by hypermail 2.4.0 : Thursday, 24 March 2022 20:42:03 UTC