- From: Phil Archer <parcher@icra.org>
- Date: Fri, 18 Jan 2008 17:16:25 +0000
- To: Jeremy Carroll <jjc@hpl.hp.com>
- CC: public-powderwg@w3.org
Good, this feels as if we're making progress (or rather, you're making progress in a promising direction :-)). I'll do some more playing around on Monday morning and see if I come up against anything we're missing. Have a good weekend and thank you. Phil. Jeremy Carroll wrote: > > Phil Archer wrote: >> >> >> Jeremy Carroll wrote: >> [snip] >>> >>> If we choose to make the GRDDL transform make the DR-S include the >>> subClassOf relationship as above, then we have the issue that in a >>> package (or any collection of DRs) some of the DRs may be valid and >>> some may be invalid, and all the subClassOf relationships are in the >>> same file, and it is unclear how to distinguish the ones we want to >>> claim (the valid ones), from the ones we don't (the invalid ones). >> >> I take this point. It may be that we can do something about it though. >> We have so far taken the view that a DR should be self-contained and >> that a package is therefore a group of self-contained units. Doing >> this means that the validity information (and attribution) is NOT >> inherited by DRs in the package. However... we then had to introduce >> the idea of using dcterms:isPartOf to force the processing of these >> "discrete DRs" in a particular order [1]. In such a scenario, yes, >> each DR would have its own validity and attribution. >> >> But it doesn't have to be this way... >> >> It would be possible I think to work with the package carrying the >> validity information that was then inherited by the DRs within that >> package - which I think from what you say would make life easier? >> >> > > > Yes - I was thinking along these lines. > > I was discussing this with Stuart - a possible view is then: > > The unit of a POWDER description is a document, which may contain a > single wdr:DR or a single wdr:Package. > > Either way the document has information pertinent to the relevance of > the document: > e.g. validity and who vouches for it. > > Operationally the process of trust is as follows: > > for each possible document that you might be considering, you read that > document, then understanding what that document says about itself, if > you are satisfied that you want to act on that document (e.g. it is > valid, and is vouched for by an appropriate authority), then you load it > into your knowledge base (formally corresponding to an RDF merge using > the POWDER-S GRDDL result) > > The resulting RDF graph consists of only valid POWDER DRs, which have > been vouched for by appropriate authorities. > > From the formal side the motivations for doing this way are: > - it is known that temporal logics (i.e. dealing with time in a logical > way) is a hard problem > - it is known that dealing with trust in logic is a hard problem > - it is clear that POWDER deals with both time and trust, but in simple > ways > - hence it feels inappropriate to do the time and trust parts in the > formal logical layer, but to deal with them in a pragmatic layer prior > to, but informed by, the logical treatment > > It is a limitation of the current RDF technology that it is hard to talk > about part of an RDF graph, and its validity, or who vouches for that > part - hence the desire to talk about documents containing RDF/XML that > expresses those parts of the graph. > I think it is possible to design documents of the 'right' size so that: > > - validity and vouching are pertinent on a document by document level > (and not on a finer grain) > - documents are large enough that the small scale powder user need only > write one document for their site, or maybe two. > > - that the expectations on large publishers who may need to make > declarations that fit into complex workflows are intelligible and not > too burdensome. > > Jeremy >
Received on Friday, 18 January 2008 17:16:36 UTC