Date: 2012-09-10 13:23:22
From: Ken.Wenzel@iwu.fraunhofer.de
Hello,
I encountered a potential bug in OWLIM SE 5.2 (with Sesame 2.6.8 and context indexes enabled)
when executing a SPARQL query where the dataset is specified with "FROM <...>" clauses
(or by using the corresponding Sesame API).
Both queries
select ?s ?p ?o from <urn:somegraph> where { ?s ?p ?o }
and 
ask from <urn:somegraph> { ?s ?p ?o }
retrieve data from <urn:somegraph> and the default graph.
But, as I understand "from <urn:somegraph>", only data contained
in <urn:somegraph> should be used to answer the query.
I am not aware of this behaviour in OWLIM Lite.
I would be glad to get some suggestions.
Regards,
Ken

asked 03 Apr '13, 10:55

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k136156214
accept rate: 30%


Date: 2012-09-20 15:40:11
From: ruslan@sirma.bg
Hi Ken,
This bug was due to incorrect setting of a flag and was fixed. It may 
also appear in SELECT queries when specifying FROM clauses and 
includeInferred is set to 'false' (additional statements from the 
default graph will appear in the query result). The fix will be 
available in the next release.
Regards,
Ruslan
link

answered 03 Apr '13, 10:55

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k136156214
accept rate: 30%

Date: 2012-09-11 10:56:24
From: barry.bishop@ontotext.com
Hi Ken,
I'm not able to reproduce this with OWLIM 5.2. I tried the following:
insert data {
skos:x skos:y skos:z .
graph skos:g { skos:a skos:b skos:c }
}
select ?s ?p ?o from skos:g where { ?s ?p ?o }
=> a b c
correct, only triples in 'g' should be used
select ?s ?p ?o where { ?s ?p ?o }
=> a b c
=> x y z
=> lots of axiomatic statements if using any rule-set apart from 'empty'
correct (for owlim, there is no standard for this), the default graph in 
the rdf dataset is made up of an RDF merge of all graphs in the database
ask from skos:g { skos:x skos:y skos:z }
=> false
correct, the triple x y z is in the default graph, which is not used
ask from skos:g { skos:a skos:b skos:c }
=> true
correct, a b c is in graph g
May I ask what kind of inference you are using? Inferred statements go 
in to the default graph,  I wonder if these have interfered with your 
experiments?
barry
link

answered 03 Apr '13, 10:55

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k136156214
accept rate: 30%

Date: 2012-09-11 09:07:34
From: Ken.Wenzel@iwu.fraunhofer.de
Hi Barry,
thank you for testing this.
I use the rule-set  "owl-horst-optimized", but I opted to NOT includeInferred in the Sesame API and the OpenRDF workbench.
Does this mean that basic axiomatic statements (RDFS, OWL) are always included when using a rule-set, even if includeInferred=false?
Ken
link

answered 03 Apr '13, 10:55

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k136156214
accept rate: 30%

Date: 2012-09-11 12:32:44
From: barry.bishop@ontotext.com
Hi Ken,
Thanks for the extra information. The bit I was missing is that the 
problem occurs with includeInferred is set to false. I can now replicate 
it and seems to be independent of the context index and the rule-set.
To summarise, an ASK query of this form:
ASK
FROM g
WHERE { x y z }
will incorrectly return true when:
a. triple 'x y z' is in the default graph (not another named graph or 
'g') and
b. includeInferred is set to false (in sesame workbench or 
programmatically or adding FROM <http://www.ontotext.com/explicit>)
This is indeed a bug and will be investigated. Thanks for reporting it.
I have not found anything wrong with SELECT queries when includeInferred 
is set to false.
For the moment, I suggest leaving your includeInferred parameter set to 
true.
I hope this helps,
barry
link

answered 03 Apr '13, 10:55

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k136156214
accept rate: 30%

Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here

By RSS:

Answers

Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text](http://url.com/ "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Tags:

×261
×242
×38

Asked: 03 Apr '13, 10:55

Seen: 931 times

Last updated: 03 Apr '13, 10:55

powered by BitNami OSQA