- From: Jim Hendler <hendler@cs.rpi.edu>
- Date: Tue, 30 Dec 2008 23:54:31 -0500
- To: Bijan Parsia <bparsia@cs.manchester.ac.uk>
- Cc: "Michael Schneider" <schneid@fzi.de>, "OWL Working Group WG" <public-owl-wg@w3.org>
OK, you (plural) have convinced me this can be useful expressivity However, given two of us who had PhDs in AI and long experience with DBs took a while to work through the semantics, and didn't get the idea of these examples without the emails from you folks, I do think documenting it will be important... On Dec 30, 2008, at 7:19 PM, Bijan Parsia wrote: > On 30 Dec 2008, at 22:50, Michael Schneider wrote: > > [snip] > >> Apart from this somewhat fancy consideration, there is a different >> aspect of >> Keys in OWL 2: They also provide for compound keys, and this is >> really an >> important RDB feature, and isn't available by inverse functional >> properties. > > I tend to consider the class part as an aspect of compoundness. > E.g., key is a hasSNN *and* being a Person. You could add arbitrary > expressions to capture more complex conditions. I.e., a key is > hasSNN *and* is a Person who was born before1928. > > For example, if you recycle IDs every 4 years (i.e., to cover > students in a 4 year program), you would want keys to be tagged to 4 > year periods: > hasKey(hasId, allvaluefrom.enrolledIn >=2004 & <= 2008) > > Similarly, if you are reconciling databases, some datasets might > have keys (like ISBN) that are unique for one part of the data but > need to be combined with another property (title) in another (due to > a change in policy). (Here the classes correspond roughly to the > core entities in each dataset, sorta like what you pointed out for > corresponding tables in classes, i.e., if you are doing data > integration, you might be pulling in multiple datasets). > > Cheers, > Bija "If we knew what we were doing, it wouldn't be called research, would it?." - Albert Einstein Prof James Hendler http://www.cs.rpi.edu/~hendler Tetherless World Constellation Chair Computer Science Dept Rensselaer Polytechnic Institute, Troy NY 12180
Received on Wednesday, 31 December 2008 04:55:24 UTC