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Subject: Minutes: XDI TC Telecon Thursday 1-2PM PT 2009-06-18
Following are the minutes of the unofficial telecon of the XDI TC at: Date: Thursday, 18 June 2009 USA Time: 1:00PM - 2:00PM Pacific Time (20:00-21:00 UTC) ATTENDING Bill Barnhill Markus Sabadello Drummond Reed REGRETS Giovanni Bartolomeo 1) UPDATES We provided some general updates since it had been a month from the last call. Drummond and Markus explained the XDI-related work they have been doing with Mydex, a new Community Interest Corporation in the U.K. focused on VRM (Vendor Relationship Management). They have also been exploring an XDI messaging application. Bill said he has been working on an activity stream application. 2) $HAS INFERRENCE Based on our conclusions in May regarding the $has metagraph predicate definition, Drummond wanted to confirm for the updated spec text that +x/$has/+y (and its inverse +y/$is$has/+x) infers exactly four XDI RDF statements: (+x/+y) +x+y +x+y/$is$a/+y +y/$a/+x+y We agreed this was the case. It can be easier to parse using a real-world example, such as: =bill/$has/+ball This infers four XDI RDF statements: (=bill/+ball) =bill+ball =bill+ball/$is$a/+ball +ball/$a/=bill+ball Bill pointed out that the N3 abbreviation for rdf:type (subClassOf) is just "a". Thus in N3 you would write: :Bill a :Person Whereas in XDI RDF we use the property $is$a for subClassOf, and the inverse - $a - for superclass. So we would write: =bill/$is$a/+person +person/$a/=bill So it is a bit confusing that our $a has the inverse semantics of the N3 "a". Unfortunately this can't be avoided for two reasons: 1) $a is our metagraph predicate for incoming arc relationships, which is the inherent basis for typing. 2) $is$a reads the same as English for expressing subClassOf relationships, e.g., =bill/$is$a/+person. So it was just an unfortunate choice that N3 choose "a" instead of "is-a" to represent subClassOf relationships. Bill also pointed out that full N3 does not directly translate into conventional RDF because it is a superset of RDF. It includes formula, variables, logical implications, and functional predicates, as well as providing a textual syntax alternative to RDF XML. In this way XDI RDF seems much closer to N3 than to conventional RDF. 3) NEW BUSINESS We discussed that if XRI Resolution 3.0 is defined abstractly with multiple bindings, XDI is one possible binding. We need to keep this in mind as the XRI TC finishes the XRI 3.0 spec suite. 4) NEXT CALL Due to travel and other conflicts, we will NOT hold a call next week, but will reconvene in two weeks, on Thursday, July 2.
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