- From: Eric Prud'hommeaux <eric@w3.org>
- Date: Thu, 8 Jun 2006 04:33:04 +0200
- To: Pat Hayes <phayes@ihmc.us>
- Cc: public-rdf-dawg@w3.org
The objective of this message is to explore the complexity of variables bound in OPTIONALs and UNIONs and used as constraints in later OPTIONALs and UNIONs. My thesis is that in certain, detectable situations, you get a factorial burden for finding the different solutions that arise from the order being arbitary (and, in fact, comprehensive). In this, the metadata for ?:bookB has evolved over time from dc1.0 to dc1.3 with different styles... data: _:bookA bib:references _:bookB . _:bookB dc10:publisher <mailto:bob> . _:book10 dc10:publisher <mailto:bob> . _:bookB dc11:publisher <mailto:bob> . _:book11 dc11:publisher <mailto:bob> . _:bookB dc12:publisher [ foaf:name "Bob" ] . _:book12 dc12:publisher [ foaf:name "Bob" ] . _:bookB dc13:publisher [ foaf:name "Bob" ] . _:book13 dc13:publisher [ foaf:name "Bob" ] . query: SELECT ?pub ?oth10 ?oth11 ?oth12 ?oth13 WHERE { ?a bib:references ?b # OPTIONAL { ?b dc10:publisher ?pub . # 10 ?oth10 dc10:publisher ?pub } # ?a bib:references ?b OPTIONAL { ?b dc11:publisher ?pub . ?oth11 dc11:publisher ?pub } ?a bib:references ?b # OPTIONAL { ?b dc12:publisher ?pub . # 12 ?oth12 dc12:publisher ?pub } # ?a bib:references ?b OPTIONAL { ?b dc13:publisher ?pub . ?oth13 dc13:publisher ?pub } } Pat, this scenario doesn't work yet, but maybe you can work out some particular of when you will get different answers if you try the 10 pattern before the 11 pattern before the 12 pattern. Note: we need the wierd repeated triples (or some triples) because while both of 11 and 12 can be processed an either order if they have a triple between the: ?a bib:references ?b # OPTIONAL { ?b dc11:publisher ?pub . # 11 ?oth11 dc11:publisher ?pub } # ?a bib:references ?b # OPTIONAL { ?b dc12:publisher ?pub . # 12 ?oth12 dc12:publisher ?pub } # without the extra triples: OPTIONAL { ?b dc11:publisher ?pub . # 11 ?oth11 dc11:publisher ?pub } # OPTIONAL { ?b dc12:publisher ?pub . # 12 ?oth12 dc12:publisher ?pub } # One must process (get bindings from) 11 before 12. Bonne chance, -- -eric home-office: +1.617.395.1213 (usually 900-2300 CET) cell: +81.90.6533.3882 (eric@w3.org) Feel free to forward this message to any list for any purpose other than email address distribution.
Received on Thursday, 8 June 2006 02:31:33 UTC