I attach the data file that I used for testing; I used it under the http://localhost:8001/LocalData/Innsbruck.rdf URI
Look at the following query: PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX p: <http://dbpedia.org/property/> SELECT * FROM <http://localhost:8001/LocalData/Innsbruck.rdf> WHERE { { } OPTIONAL { <http://dbpedia.org/resource/Innsbruck> owl:sameAs ?same. } } I would expect the result: ---------------------------------- same ---------------------------------- <http://sws.geonames.org/2775220/> ---------------------------------- This is also the result coming from SPARQLer. If I modify the query with the addition of a non-empty group at the beginning PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX p: <http://dbpedia.org/property/> SELECT * FROM <http://localhost:8001/LocalData/Innsbruck.rdf> WHERE { { <http://dbpedia.org/resource/Innsbruck> a <http://dbpedia.org/class/City>. } OPTIONAL { <http://dbpedia.org/resource/Innsbruck> owl:sameAs ?same. } } then you return the right result. Ie: it seems that you consider an empty {} in the pattern as some sort of a False value the kills the rest. Ivan -- Ivan Herman, W3C Semantic Web Activity Lead URL: http://www.w3.org/People/Ivan/ PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html FOAF: http://www.ivan-herman.net/foaf.rdf
Innsbruck.rdf
Description: application/rdf
smime.p7s
Description: S/MIME Cryptographic Signature
