Initial content for 'Inference Rules'

[afs]

First pass at content for SHACL rules.

• See this document rendered online here

While this is a draft pull request, the important concerns are structure and design.

[HolgerKnublauch]

Great start! I am assuming there will be some (RDF) vocabulary like sh:rule that links those rules to shapes, so that the target mechanisms come into the mix?

[afs]

Great start! I am assuming there will be some (RDF) vocabulary like sh:rule that links those rules to shapes, so that the target mechanisms come into the mix?

That's the plan - it's in gist sketch.

Targets sh:targetClass (and its implicit form), sh:targetSubjectsOf and sh:targetObjectsOf are equivalent to triple patterns so make that syntax logically map to a generator of $this -- $this a :Class, $this :property ??, ?? :property $this -- and can be made to work for forward and backward implementation.

sh:targetNodes with node expressions may need limiting to the node expressions evaluated over the base graph, not triples currently being inferred. Node expressions are opaque as to what they depend on so backward chaining breaks and forward chaining can only work by blindly re-evaluating.

Similarly sh:target [ a sh:SPARQLTarget ; - though often that can be triple patterns.

So for regularity, maybe all targets should be "base graph only" generators of $this - run the rule once at the start of general evaluation.