add section about 'unstar' mapping

[pchampin]

as per w3c/rdf-star-wg#129

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Preview | Diff

[afs]

Is this proposed "as well as" the graph-to-graph algorithm or "instead of"?

w3c/rdf-star-wg#114 (comment)

[niklasl]

This approach requires graphs containing triple terms to be represented as datasets. That excludes cases where you need to put "unstarred" RDF 1.2 graphs into an RDF 1.1-based quad store and manage them within specific named graphs. Implementations supporting the default graph union mechanism would also treat the "triple term graphs" as asserted in that union graph.

[niklasl]

It has been mentioned (or opined) that the "star" name would eventually go away (it would be just RDF 1.2 with triple terms). If so, perhaps "unstar" is an unfortunate name for future reference?

[rat10]

There seems to be an issue with the examples section: all examples say "Cannot GET /uploads/dcqFS6/spec/ex-unstar-output.trig".

[gkellogg]

There seems to be an issue with the examples section: all examples say "Cannot GET /uploads/dcqFS6/spec/ex-unstar-output.trig".

It's the general PR-preview issue of not being able to retrieve neighboring resources. They are fleshed out if you look at the GitHack version.

[pchampin]

Is this proposed "as well as" the graph-to-graph algorithm or "instead of"?

I personally don't think that we should have multiple such mappings, and I am more and more convinced that the graph-to-graph approach makes more sense.

The reasons I stuck to my initial graph-to-dataset approach in this PR are that

• I am still not clear about the details of the graph-to-graph approach, and
• I wanted to write down the design goals of the mapping, so that we can discuss them (and inform the responses to the previous point).

[rat10]

What is the "graph-to-graph" algorithm? A mapping based on the RDF standard reification vocabulary?

[niklasl]

What is the "graph-to-graph" algorithm? A mapping based on the RDF standard reification vocabulary?

Or something isomorphic to it but using dedicated terms. There's an example of that in this recent wiki page (with links to w3c/rdf-semantics#49 and w3c/rdf-star-wg#114.).