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Subject: $has and $has$a distinction (was RE: Minutes: XDI TC Telecon Thursday 1-2PM PT 2009-03-26)
Giovanni et al, See the responses I entered into the Open Issues part of the wiki page: http://wiki.oasis-open.org/xdi/XdiMetamodel I believe we have a misunderstanding about the semantics of $has and $has$a, and that misunderstanding is causing other problems, all of which I believe are solved if we clear up that misunderstanding. In fact I feel that this part of the XDI RDF metamodel is becoming more and more solid, so I'm particular interested in discussing it on tomorrow's telecon to see if we can clear up this misunderstanding. Giovanni, note that we will be using a NEW telecon service tomorrow that is MUCH better for Skype connections. Hopefully it will be much clearer. Talk to you then, =Drummond > -----Original Message----- > From: Giovanni Bartolomeo [mailto:giovanni.bartolomeo@uniroma2.it] > Sent: Monday, March 30, 2009 9:50 AM > To: 'OASIS - XDI TC' > Cc: Drummond Reed > Subject: Re: [xdi] Minutes: XDI TC Telecon Thursday 1-2PM PT 2009-03-26 > > Hello, > > sorry for not having able to attend this call. However, I'm starting > to realize that we all have probably similar views, but not the same! > This is probably due because we have started from an existing set of > defined $ words, and we are assigning semantics to them trying to > cover different use cases. A proposal could be to revert this > procedure, starting from requirements and check what $ words we need > (and what semantics should be them assigned). I've added this as an > issue in the wiki page XdiMetamodel, focusing for the time being only > on the usage of $ words in the metamodel: > http://wiki.oasis-open.org/xdi/XdiMetamodel#head- > 97f5b1e080d47401763a7afd5e601ee766c5fea6. > All comments are welcome! > > Thanks, > Giovanni > > At 06.31 27/03/2009, Drummond Reed wrote: > >Following are the minutes of the unofficial telecon of the XDI TC at: > > > >Date: Thursday, 26 March 2009 USA > >Time: 1:00PM - 2:00PM Pacific Time (21:00-22:00 UTC) > > > >ATTENDING > > > >Markus Sabadello > >Nick Nicholas > >Drummond Reed > >John Bradley > >Bill Barnhill > > > >REGRETS > > > >Giovanni Bartolomeo > > > > > >1) CONTINUE $HAS AND +X/+Y/+X+Y DISCUSSIONS > > > >See the minutes of the last two meetings at: > > > > [1] http://lists.oasis- > open.org/archives/xdi/200903/msg00005.html > > [2] http://lists.oasis- > open.org/archives/xdi/200903/msg00018.html > > > >Also the posts at: > > > > [2] http://lists.oasis- > open.org/archives/xdi/200903/msg00004.html > > [3] http://lists.oasis- > open.org/archives/xdi/200903/msg00006.html > > [4] http://lists.oasis- > open.org/archives/xdi/200903/msg00007.html > > [5] http://lists.oasis- > open.org/archives/xdi/200903/msg00008.html > > > >The main page we discussed on this call was the new XDI Metamodel page: > > > > http://wiki.oasis-open.org/xdi/XdiMetamodel > > > >We began by discussing the proposition brought up last week, i.e., that > the > >$has predicate emight be a generalization of all predicates (all arcs). > Bill > >explored this by explaining all the pairings he derives from > >=abraham/+son/=isaac (@=, =abraham), (+metadata+described, =abraham), > >(=abraham, =abraham+son), (+son, =abraham+son). He said they are in the > form > >(group-id, member-id). > > > >Drummond explained that he felt strongly that $has was not the > >generalization of all predicates, but in fact that it had very > specialized > >purpose and semantics vs. $has$a. For example, =abraham+son infers the > >metagraph statement =abraham/$has/+son. This also asserts a cardinality > of > >exactly one +son outgoing arc from =abraham that has an object > =abraham+son. > > > >In addition it infers that: > > > > a) =abraham/$has$a/+son, but does NOT infer any cardinality of > the > >number of sons. > > b) =abraham+son/$is$a/+son, but does NOT infer any instances of > >sons. > > > >We then compared RDF and XDI RDF statements. Bill gave the example: > > > > foaf:Person has a property ex:son > > Abraham is a instance of foaf:Person > > Abraham has a property of ex:son > > > >Those same statements in XDI RDF (roughly): > > > > +person/$has$a/+son > > =abraham/$is$a/+person > > =abraham/$has$a/+son > > > >Drummond pointed out that the last statement means =abraham/+son, not > >=abraham+son. The latter would be the metagraph statement > >=abraham/$has/+son. > > > >Bill said that in term of his groupID, memberID pairs, this would be > >+person=abraham, =abraham+son. > > > >Drummond gave the same example in English of "Boeing has a airplane > called > >[list of airplane objects here]" and "Boeing airplanes" as a noun. > > > > > >Bill said, "So you're saying @boeing+plane(xx) => (xx) is a class, and > >@boeing/+plane/(xx) => (xx) is an instance? Drummond agreed. > > > >Nick noted that there is a confusion between $has at the graph and > metagraph > >level, and also that we need to discuss arcs between two individuals (vs. > >arcs from a class to an individual). > > > ># DRUMMOND to make that a topic for next weeks call. > > > >Bill also noted the following link to a good series of posts on A-Box vs > >T-Box: > > > > http://www.mkbergman.com/?p=471 > > > >And also that for the next call, one method of whiteboarding is to use > the > >Coccinella client: > > > > http://thecoccinella.org/download > > > > > >2) NEXT CALL > > > >Regular time, 1-2PM PT (20:00-21:00 UTC). > > > > > >--------------------------------------------------------------------- > >To unsubscribe from this mail list, you must leave the OASIS TC that > >generates this mail. Follow this link to all your TCs in OASIS at: > >https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php > > > > --------------------------------------------------------------------- > To unsubscribe from this mail list, you must leave the OASIS TC that > generates this mail. Follow this link to all your TCs in OASIS at: > https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
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