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Re: inverse properties in JSON-LD

From: Ivan Herman <ivan@w3.org>
Date: Mon, 3 Oct 2011 13:17:33 +0200
Cc: public-linked-json@w3.org
Message-Id: <F4C001C1-92F7-4290-8B75-02FD03F3D85C@w3.org>
To: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>
Hi pa, 

I guess this is the analogue of the usage of @rev in RDFa.

There has been lots of discussion in the RDFa WG at some point whether @rev is necessary at all. The completely anecdotical evidence (ie, not based on hard crawl results, for example) is that @rev is very rarely used in deployed RDFa. As Manu pointed out, the JSON community is not the same as the Web developers' community but, nevertheless, this may be an indication that the take up of such a feature would not be big...

On the other hand, the fear I have is that, while the behaviour of this is pretty clear to you or me or Manu or people who think essentially in triples, it might be fairly confusing for those who come from a different direction:-( Such a confusion could backfire on us.

Of course, we could have a separate 'obscure^H^H^H^H^H^H^Hadvanced features' or something in the document:-)

Ivan


On Oct 3, 2011, at 12:57 , Pierre-Antoine Champin wrote:

> Hi all,
> 
> is there any plan in JSON-LD to provide a way to declare an *incoming*
> arc, for example
> 
>  {
>    "@subject": "#me",
>    "http://xmlns.com/foaf/0.1/member": {
>       "@inverse": "http://univ-lyon1.fr/#this"
>    }
>  }
> 
> producing the following triple
> 
>  <http://univ-lyon1.fr/#this>
>     <http://xmlns.com/foaf/0.1/member> <#me> .
> 
> 
> This would prove very useful with a coercion rule, as I would (much!)
> rather write:
> 
>  {
>    "@context": {
>      "foaf:": "http://xmlns.com/foaf/0.1/",
>      "memberOf": "http://xmlns.com/foaf/0.1/member",
>      "@coerce": {
>        "@inverse": "memberOf"
>      }
>    }
> 
>    "@type": "foaf:Person",
>    "foaf:name": "Pierre-Antoine Champin",
>    "memberOf": [
>      "http://univ-lyon1.fr/#this", "http://liris.cnrs.fr/#this"
>    ]
>  }
> 
> (with the context possibly kept off-band) than write:
> 
>  {
>    "@context": {
>      "foaf:": "http://xmlns.com/foaf/0.1/",
>      "@coerce": {
>        "@iri": "foaf:member"
>      }
>    }
>    "@subject": [
>      {
>        "@subject: "_:me",
>        "@type": "foaf:Person",
>        "foaf:name": "Pierre-Antoine Champin",
>      },
>      {
>        "@subject: "http://univ-lyon1.fr/#this",
>        "foaf:member": "_:me"
>      },
>      {
>        "@subject: "http://liris.cnrs.fr/#this",
>        "foaf:member": "_:me"
>      }
>    ]
>  }
> 
> 
> pa
> 
> 
> PS: as I see it, "@inverse" would imply "@iri", as the subject of a
> triple has to be an IRI in RDF.
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
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Received on Monday, 3 October 2011 11:16:43 GMT

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