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Re: swp:assertedBy

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 15 Apr 2004 01:53:31 -0500
Message-Id: <p06001f7cbca3a76bcdd6@[10.0.100.76]>
To: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Cc: Patrick Stickler <patrick.stickler@nokia.com>, Chris Bizer <chris@bizer.de>, www-archive@w3.org
>Pat
>
>part 1:
>I think we made progress ...
>    swp:assertedBy . swp:authority
>  is true when the authority asserts the graph,
>part 2:
>  and from the point of view of the authority, this includes the 
>truth of the graph itself.

Yes, but it is hard to express 'point of view' formally.

>
>(note we had that when the authority provided the graph, but that is 
>not needed, if Pat asserts `Jeremy asserts "foo bar"', then for me, 
>`Jeremy asserts "foo bar"' is true if:
>a) I asserted "foo bar"
>and
>b) "foo bar"
>
>even though you (or anyone else) might be providing the graph.


Yes, your objections were good and I had to think it all through again.

Let me summarize my own current understanding informally first (as 
much for my own benefit as for y'alls) .

The way I had it, a warrant graph asserting G entailed G, which was 
wrong. The warrant graph just says that the authority asserts G, but 
G doesn't follow from that alone (since I can believe that without 
believing that G is true) . I had been looking at it all from the 
asserter's point of view, not the reader's point of view.

(What might be the case, plausibly, is that if you trust the 
authority then you should believe what the authority asserts: that 
is, G is entailed by the conjunction of an assertion that the 
authority is trustworthy and a warrant of an assertion of G by the 
authority. But this inherently involves trust. Without some trusting 
going on, you can never formally derive an asserted graph from an 
assertion of the graph by any authority. (You might not even trust 
yourself in some extreme circumstances.) )

We assume three notions as primitive: that of an 'authority' which is 
some kind of legal or social entity which can be referred to by a URI 
(so is the 'person' in the domain of discourse) , and a relationship 
between such authorities and graphs which we will call being the 
authority of, or authorizing, the graph, and the idea of a warrant. 
Exactly what these mean is not specified formally, but intuitively 
the authority is the entity which accepts responsibility for standing 
behind what the graph 'says'. We suggest two techniques for detecting 
the presence of the authority of a graph and of an authorization 
relationship:  by being published on the website belonging to the 
authority, or by being signed with a signature of the authority.

Authorities can also stand in some kind of propositional-attitude 
relationship to a graph, such as asserting it, denying it or quoting 
it.  A warrant is a thing that connects all this together: a warrant 
graph describes it (so is true or false depending on whether the 
relationship of authorizing holds or does not hold) and can also 
under some circumstances, acting as a performative, actually make the 
relationship it describes be true. To do this the authority it 
describes has to really be authorizing the graph in question. In this 
case the warrant graph actually *is* a warrant (given the presence of 
the authorizing relationship) and so is sufficient to ensure the 
truth of the warrant description considered as a piece of RDF. This 
allows other kinds of warrants to exist, but still gives the 
performative force.

Being asserted/quoted/whatever by a self-describing warrant is just 
true by fiat: if you say you are asserting G, then you are asserting 
G, etc..  But the formal story ends there, and we only get 
connections between assertions of G and G itself by invoking a trust 
policy.

-------

Changes to the text attached in TEX format which I am slowly learning 
(they will need some formatting work for the footnote and figure, but 
I hope they are not completely hopeless.)
There are a few comments inserted in TODOs: delete after reading.  I 
figured we had to rewrite section 5.1 and 5.2 as well as the formal 
stuff in 6. These are intended to be complete replacements for the 
text in these subsections, so if something is omitted that is 
deliberate.

Those files are also on my website, in case the attachments get screwed.

Sorry it took me so long to grok what y'all have been talking about.

Pat

PS. In section 4  we say "There are currently two ..."  Aren't there 
rather more than two, in fact?


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Received on Thursday, 15 April 2004 02:53:47 GMT

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