- From: Bijan Parsia <bparsia@cs.man.ac.uk>
- Date: Wed, 6 Sep 2006 15:37:39 +0100
- To: Bijan Parsia <bparsia@cs.man.ac.uk>
- Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Jorge pointed out to me off list that I forgot to mention that the *data* complexity of nested optionals is logspace, which is quite normal in the DB world. (You can see that result in the paper where I pointed.) OTOH, he said that they had a results (not included in the paper) that the complexity without nesting is NP-hard (not in NP). So, the difference between unnested and nested is probably moot. He also said that he thought it was a worthwhile feature and could be made clear and correct, but that we had some decisions to make to nail it down. I'll keep up that conversation and report back to the working group, with an eye to getting a concrete proposal/presentation. I'm not sure where this leaves my desire to reraise the issue. I think it's still new information, but that I need to do more investigation to determine what I think. A methodological point: One thing I've been looking for as I work through the spec for holes, is things which we might add (usually clarifications) or subtract (typically features) with an eye to having a well, clear, consistent, intelligible specification in the time frame we have. The group has produced a language which is very expressive, with *interesting* expressivity, but expressivity that is not well understood, overall, at least by me, even in the simple entailment case. This worries me. That other people who have expertise in lots of areas that are foreign lands to me have had similar problems indicates that we have a significant challenge ahead. I would feel more comfortable with a smaller language this time around, with a working group submission for the extra functionality to give time for people to really pound on the interesting new features. It's unclear that this is a possibility or, overall, pragmatically desirable at this time. This is just my methodology. The goal I have I think is shared by us all: A great spec and language by the end of the year. I hope we can make it. Cheers, Bijan.
Received on Wednesday, 6 September 2006 14:37:42 UTC