- From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
- Date: Wed, 13 Jul 2016 07:52:52 -0700
- To: james anderson <james@dydra.com>, public-sparql-exists@w3.org
On 07/13/2016 01:36 AM, james anderson wrote: > good morning; [...] > the example intends to show just _the kinds of things_ which one needs to have > in one place in order to understand an issue. > as jeen broekstra is the only one who understood this intent, i changed it to > make it less likely that one misinterpret it as an actual issue description. > > best regards, from berlin, > --- > james anderson | james@dydra.com <mailto:james@dydra.com> | http://dydra.com I don't see a need for this at all. Yes, eventually there needs to be examples than can be run through SPARQL implementations to see what they do. That's the goal of a test suite and the format this already exists (but it may need a bit of change for our purposes). As this format is not machine-executable it does not fit this need. Yes, there needs to be a description of the problem and, eventually, what should be done. This description should be concise, readable, flexible, and easy to create. This format does not appear to fit any of these characteristics. I think that an open format is much better at the initial stages. Consider the first problem that I identified in my earlier message. The most-recent plain text description is: ******* Problem 1: Some uses of EXISTS are not defined during evaluation The evalution of exists in 18.6 is only defined for graph patterns, but in SELECT ?x WHERE { ?x :p :c . FILTER EXISTS { SELECT ?y { ?y :q :c . } } } the argument to exists ends up being a ToMultiSet, which is not listed under "Graph Pattern" in the table of SPARQL algebra symbols in 18.2. The argument to exists is not explicitly listed as a "Graph Pattern" when the argument to EXISTS is a GroupGraphPattern containing just a SubQuery or just an InlineData. Here the join is simplified away by section 18.2.2.8 leaving a construct in the SPARQL algebra that is not listed as a graph pattern symbol, ToMultiSet or a multiset, respectively. An example of where this happens (but not at the top level of an EXISTS) is the last example of 18.2.3. ******* Note that there is no intended solution here nor is there any graph as this not a problem with the result of the query against any particular graph or dataset. It may be that this problem will spawn multiple example queries and even more example tests. Free-format text (hopefully with clickable links) can handle this much better than a example-per-issue format. I do believe that it is useful to put this sort of information into an area that can be easily edited by group members. The W3C wikis appear to me to be a good candidate for this purpose - can this group get one? If not, maybe the github wiki can be used, but not with a fixed format per issue. peter
Received on Wednesday, 13 July 2016 14:53:24 UTC