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RE: blank predicates

From: William Van Woensel <William.Van.Woensel@Dal.Ca>
Date: Sat, 28 Mar 2020 19:06:42 +0000
To: "public-lod@w3.org" <public-lod@w3.org>
CC: 'Doerthe Arndt' <doerthe.arndt@ugent.be>
Message-ID: <YTOPR0101MB15306C1AC8464E2DC4130057D4CD0@YTOPR0101MB1530.CANPRD01.PROD.OUTLOOK.COM>
Hello everyone,

Note that reification as proposed by some (either directly or via RDF*) does not seem wholly applicable, since the reified triple does not entail<https://www.w3.org/TR/rdf11-mt/#whatnot> the “original” triple (and vice-versa).

N3 logic, which exists on top of RDF, allows predicates to be blank nodes (see here<https://github.com/w3c/N3/blob/master/grammar/n3.g4> for the syntax). For example, it supports the statement “:Alice [] :Bob”. In essence, this is identical to stating “@forSome :pred . :Alice :pred :Bob” . Similar to Masahide’s example, the blank node could then be further described, for instance.

Not saying that this is the best solution for your case – just that N3 would allow you to use a blank node for your predicate.

There are several implementations of N3 currently available (with more in the pipeline): Eye<https://github.com/josd/eye> and Cwm<https://www.w3.org/2000/10/swap/doc/cwm.html>. The standard is currently being more formally defined and extended; we currently have an active W3C community group<https://www.w3.org/community/n3-dev/>.



Regards,

William


From: john.nj.davies@bt.com <john.nj.davies@bt.com>
Sent: March-28-20 3:29 PM
To: danbri@danbri.org; cstadler@informatik.uni-leipzig.de
Cc: public-lod@w3.org; melvincarvalho@gmail.com
Subject: RE: blank predicates

CAUTION: The Sender of this email is not from within Dalhousie.
Yep

From: Dan Brickley <danbri@danbri.org<mailto:danbri@danbri.org>>
Sent: 28 March 2020 12:08
To: Claus Stadler <cstadler@informatik.uni-leipzig.de<mailto:cstadler@informatik.uni-leipzig.de>>
Cc: Linked Data community <public-lod@w3.org<mailto:public-lod@w3.org>>; Melvin Carvalho <melvincarvalho@gmail.com<mailto:melvincarvalho@gmail.com>>
Subject: Re: blank predicates


yup - really just invent a property for it

or say nothing by not adding a triple

unless you have some kind of idea how the things are sort-of related then the triple adds literally no information



On Sat, 28 Mar 2020 at 10:19, Claus Stadler <cstadler@informatik.uni-leipzig.de<mailto:cstadler@informatik.uni-leipzig.de>> wrote:

<> is a relative IRI with an empty string relative to some base IRI - so Linked Data clients will typically replace it with the file:// or http(s):// URL of the document they read from.

So don't use that, unless you want location-dependent predicates :)



Cheers,

Claus


On 28.03.20 11:03, Melvin Carvalho wrote:


On Sat, 28 Mar 2020 at 10:53, Dan Brickley <danbri@danbri.org<mailto:danbri@danbri.org>> wrote:

there are an infinite number of boring relationships that hold between any arbitrary pair of objects; your best bet might be to name one for your application rather than attempt to use generalized (predicateless) rdf

So maybe simply <> ?

#Alice <> #Bob .


Dan

On Sat, 28 Mar 2020 at 08:57, Melvin Carvalho <melvincarvalho@gmail.com<mailto:melvincarvalho@gmail.com>> wrote:
I am working on a information mapping system (aka mind maps)

And I want to have two nodes related to each other

#Alice R #Bob

In the general sense, the type of relationship (predicate) R is not really known at the time of creation.  My software currently does not allow the labeling of edges is the reason (but hopefully in future it will)

I need a way to relate Alice to Bob but I dont have a URI for a predicate.

Is there something that can operate as a "blank predicate"?

Or some existing relations that simply says that two entities or linked / related, without yet knowing how they are related?

--

Dipl. Inf. Claus Stadler

Department of Computer Science, University of Leipzig

Research Group: http://aksw.org/

Workpage & WebID: http://aksw.org/ClausStadler

Phone: +49 341 97-32260
Received on Saturday, 28 March 2020 19:06:58 UTC

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