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scope of blank node identifiers and multiple graphs

From: François-Paul Servant <francoispaulservant@gmail.com>
Date: Mon, 30 Jan 2017 17:51:55 +0100
Message-Id: <DFD3073E-BAF8-4017-9181-89A2AB20844C@gmail.com>
To: public-linked-json@w3.org
Hi,

the spec 
https://www.w3.org/TR/json-ld/#identifying-blank-nodes
says that 
"The blank node identifier is scoped to the document in which it is used.”

What happens when the same blank node identifier is used within 2 different graphs? There seems to be a conflict (or an ambiguity) with the usual interpretation of blank nodes identifiers in RDF.

Here is a test in the playground (2 blank nodes with same identifier _:b0 in different graphs)

http://json-ld.org/playground/#startTab=tab-normalized&json-ld=%7B%22%40graph%22%3A%5B%7B%22%40id%22%3A%22_%3Ab0%22%2C%22label%22%3A%22label%20of%20anon%20res%20in%20default%20graph%22%7D%2C%7B%22%40graph%22%3A%5B%7B%22%40id%22%3A%22_%3Ab0%22%2C%22label%22%3A%22label%20of%20anon%20res%20in%20graph%202%22%7D%2C%7B%22%40id%22%3A%22http%3A%2F%2Fex.com%2Fs2%22%2C%22p%3A2%22%3A%7B%22%40id%22%3A%22_%3Ab0%22%7D%7D%5D%2C%22%40id%22%3A%22http%3A%2F%2Fex.com%2Fg2%22%7D%2C%7B%22%40id%22%3A%22http%3A%2F%2Fex.com%2Fs%22%2C%22p%22%3A%22_%3Ab0%22%7D%5D%2C%22%40context%22%3A%7B%22p%22%3A%7B%22%40id%22%3A%22http%3A%2F%2Fex.com%2Fp%22%2C%22%40type%22%3A%22%40id%22%7D%2C%22label%22%3A%7B%22%40id%22%3A%22http%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23label%22%7D%7D%7D


Should the spec be interpreted as saying :
- there is one thing identified by “_:b0”. All statements in the document involving it refer to the same thing, whatever the @graph they are in
- there are 2 different things that should not be conflated (RDF point of view, as expressed in the N-Quads output)
- do what you want, I don’t care, only RDF-minded persons have this kind of concerns ;-)

TIA

fps
Received on Monday, 30 January 2017 16:52:30 UTC

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