Re: Named graphs etc

Hi,

another question, that I think would be interesting to discuss. We always
speak about agents referring to graphs.

What about agents referring to parts of graphs e.g. statements?

I have discussed this with Jeremy before and we didn't get to a clear
solution. Take for example agent A asserting G1 and publishing it in
Doc1.trix

G1 (ex:water ex:is ex:blue.
        ex:sky ex:is ex:blue.
        G1 trix:assertedBy ex:AgentA)

Now agent B wants to assert, that "Sky is blue" is false. And/or he also
wants to assert that he doesn't believe the assertion of agent A that that
the "Sky is blue" without questioning that agent A asserted G1.

I see different approches on different levels for this.

1. Agent B could assert

G2 (ex:sky ex:is ex:blue)
G3 (G2 ex:truthValue ex:false.
       G3 trix:assertedBy ex:AgentB)

Meaning he would repeat the part of G1 he wants to talk about and make
assertions about the repeated part. With this solution it is not possible to
figure out that B was speaking about a assertion of agent A and not a
assertion of agent C. Is this a problem?

 I also took a look at the TAG Web Architecture Draft. In section 4.4. they
recommend: Language designers SHOULD provide mechanisms for identifying
links to other resources and to portions of representation data (via
fragment identifiers). So let's try fragment identifiers :-)
2. Agent B could assert:

G4 (G1#ex:sky/ex:is/ex:blue ex:truthValue ex:false.
       G4 trix:assertedBy ex:AgentB)

The s p o parts of the fragment identifier include other fragment
identifiers, they would have to be escaped somehow to prevent fragments of
fragments and to allow parsing.

In this solution I think agent B refers directly to the graph G1 which has
been asserted by A, thus we have a direct link between A and B and know B is
not talking about assertions of C. Do you agree? What do you think about the
fragment identifier approach?

3. Another possibility are fragment identifiers on serialized document
level, something like

G4 (doc1.trix#someXPathExpression ex:truthValue ex:false.
       G4 trix:assertedBy ex:AgentB)

I think XPath doesn't work, because of the TAG finding on the relation
between URI, resource and representation and our definition that a graph
name refers to a equivalence class of graphs. Did I get this right?

Chris

Received on Friday, 12 March 2004 08:26:24 UTC