Date: 2013-02-15 13:23:38
From: andreas.schwarte@fluidops.com
Hi everyone,
we are experiencing some unexpected behaviour in evaluating queries
containing the owl:sameAs predicate. In particular, we noticed that
"owl:sameAs" triples are not (always) returned as part of the query result.
We are using OWLIM 5.3 Build 5777 and are aware that there was fix for
owl:sameAs triples in this version (This version resolved our problem
partially).
Let me try to summarize the behaviour.
We have an OWLIM repository containing multiple triples of the form (ex:s
owl:sameAs ex:other), in the particular scenario these are links from
DBpedia 3.8 files. We verified that the triple size of the repository as
given by the repository#size() and properties file are correct according to
the loaded data, i.e. it seems that the triples are physically available in
the repository.
Now, coming to the somewhat unexpected behaviour:
Assume I want to evaluate the boolean query "ASK { ?x <
http://www.w3.org/2002/07/owl#sameAs> ?o }" against this repository (which
is expected to return "true" according to our data). Then for different
settings I get the following results:
SPARQLRepository => false
HTTPRepository (includeInferred=false) => true
HTTPRepository (includeInferred=true)  => false
Workbench (includeInferred=false) => true
Workbench (includeInferred=true) => false
Using the special named graph in the query, I always get "true", i.e. "ASK
FROM <http://www.ontotext.com/explicit> { ?x <
http://www.w3.org/2002/07/owl#sameAs> ?o }"
Can someone please comment on this issue? For me in particular the
SPARQLRepository case is relevant, as I do not have the chance to set
"includeInferred" to false there at all. Is there a possibility in OWLIM to
set the default value used?
Thanks a lot and best regards,
Andreas

asked 03 Apr '13, 12:40

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k133156205
accept rate: 30%


Date: 2013-02-19 08:35:48
From: barry.bishop@ontotext.com
Hello Andreas,
It does seem that there is some further problem when queries use 
owl:sameAs triple patterns. The good thing is that the behaviour is 
consistent across all the different invocations you described, which is 
basically that when includeInferred=true then the ask query returns 
false and vice versa.
I'm afraid I don't think there is a way to set the default value for 
includeInferred when using SPARQLRepository.
I'll schedule this issue to be investigated by the development team and 
get back to you as soon as possible.
Thanks for you patience in the meanwhile,
barry
link

answered 03 Apr '13, 12:40

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k133156205
accept rate: 30%

Date: 2013-03-06 09:59:10
From: andreas.schwarte@fluidops.com
Hello Barry,
I was wondering if there are any new insights to the "owl:sameAs" behaviour
that you can share, and in particular whether/how you plan to change the
behaviour in one of the next releases of OWLIM.
Thanks a lot,
Andreas
link

answered 03 Apr '13, 12:40

Discussion-Board-Archive's gravatar image

Discussion-B...
6.1k133156205
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

Asked: 03 Apr '13, 12:40

Seen: 1,157 times

Last updated: 22 May, 05:41

powered by BitNami OSQA