- From: Chimezie Ogbuji <ogbujic@ccf.org>
- Date: Mon, 04 Jun 2007 09:55:50 -0400
- To: "public-rdf-dawg" <public-rdf-dawg@w3.org>

Per my action [1] from the last teleconference: Below is a bit of what I had in mind with regards to having our SPARQL test coverage criteria be driven by evaluation semantics as well as grammar permutations. The primary motivation is the fact that, at its essence, the SPARQL algebra only consists of a handful of symbols and by enumerating their various permutations you get decent coverage of the evaluation semantics. In particular, after converting the abstract syntax tree to its equivalent SPARQL algebra expression, each GroupGraphPattern can be treated [2] as a list of expressions against which a fold [3] function can be applied. This significantly reduces the number of permutations to consider as the (lambda) function supplied to fold takes only two arguments. If you ignore FILTER expressions (for now), the left argument can only be one of: I. LeftJoin(BGP(..),{..}) II. Join(BGP(..),Graph(varOrIRI,{..})) III. Join(BGP(..),Union(A,B)) IV. Graph(varOrIRI,{..}) V. LeftJoin({},{ .. }) - reduces to solutions for {} VI. Union(A,B) VII. BGP(..) <-- not accounted for The right argument can only be one of the same with the exception of: LeftJoin(<insert left argument>,{ .. }) Where the left argument can be an empty graph pattern ({}) or otherwise. The first case is already covered, the second depends on what the left argument is. One such scenario (where the left argument is a BGP) is already covered by I. By themselves, most (if not all) of these forms are probably already covered by previous tests. When you consider the application of the fold function to be equivalent to the Join operator (this follows from 12.2.1 Converting Graph Patterns) then you get the following permutations (skipping various simplifications and eliminating duplicates - for brevity). 1. LeftJoin(LeftJoin(BGP(..),{ .. }),{ .. }) 2. LeftJoin({},{ .. }) - covered by V. 3. Join(LeftJoin(BGP(..),{ .. }),LeftJoin(BGP(..),{ .. })) 4. Join(LeftJoin(BGP(..),{ .. }),LeftJoin({},{ .. })) - covered by I. 5. Join(LeftJoin(BGP(..),{ .. }),Union(A,B)) 6. LeftJoin(Join(BGP(..),Graph(varOrIRI,{..})),{ .. }) 7. Join(Join(BGP(..),Graph(varOrIRI,{..})),Union(A,B)) 8. LeftJoin(Join(BGP(..),Union(..)),{ .. }) 9. Join(Join(BGP(..),Union(..)),Union(A,B)) 10. LeftJoin(Graph(varOrIRI,{..})),{ .. }) 11. Join(Graph(varOrIRI,{..})),Union(A,B)) 12. LeftJoin(LeftJoin({},{ .. }), { .. }) 13. LeftJoin(LeftJoin({},{ .. }), Union(A,B)) 14. LeftJoin(BGP(..), { .. }) 15. Join(BGP(..),Join(BGP(..),Union(A,B))) 16. Join(BGP(..),Join(BGP(..),Graph(varOrIRI,{..}))) 17. Join(BGP(..),LeftJoin(BGP(..),{..})) 18. Join(BGP(..),BGP(..)) 19. Join(BGP(..),Graph(varOrIRI,{..})) - covered by 6,7 20. Join(BGP(..),Union(A,B)) - covered by 15 This is just a start and does not represent exhaustive coverage (neither FILTERs nor solution modifiers were considered), but it gives a top level criteria for test coverage of the evaluation semantics of the SPARQL algebra. I'm pretty sure a significant number of these forms are already covered by existing tests. [1] http://www.w3.org/2007/05/29-dawg-minutes.html#action09 [2] http://svn.rdflib.net/trunk/rdflib/sparql/Algebra.py [3] http://en.wikipedia.org/wiki/Fold_%28higher-order_function%29 -- Chimezie Ogbuji Lead Systems Analyst Thoracic and Cardiovascular Surgery Cleveland Clinic Foundation 9500 Euclid Avenue/ W26 Cleveland, Ohio 44195 Office: (216)444-8593 ogbujic@ccf.org =================================== Cleveland Clinic is ranked one of the top 3 hospitals in America by U.S.News & World Report. Visit us online at http://www.clevelandclinic.org for a complete listing of our services, staff and locations. Confidentiality Note: This message is intended for use only by the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and destroy the material in its entirety, whether electronic or hard copy. Thank you.

Received on Monday, 4 June 2007 13:56:25 UTC