Date: 2012-09-28 10:16:54
From: antoine.zimmermann@gmail.com
Hello,
OWLIM reasoner is materialising inferences using forward chaining
rules, and it supports named graphs.
The documentation explains the rules on plain RDF graphs, but nothing
is said about what happens to triples that are inside named graphs.
For instance, what would be materialised if I have the following named graphs?
<ng1> {  <X>  rdfs:subClassOf  <Y> .  <a>  rdf:type  <X> }
<ng2> {  <Y>  rdfs:subClassOf  <Z> .  <b>  rdf:type  <X> }
Best,

asked 03 Apr '13, 11:02

Discussion-Board-Archive's gravatar image

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


Date: 2012-10-03 11:34:06
From: barry.norton@ontotext.com
Yes, also <Y> rdfs:subClassOf <T>
<T> rdf:type rdfs:Class
and many others
Barry
link

answered 03 Apr '13, 11:03

Discussion-Board-Archive's gravatar image

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

Date: 2012-09-28 10:31:19
From: barry.norton@ontotext.com
OWLIM, as Sesame, infers triples into the unnamed graph. You've exactly 
illustrated why: the triple <b> rdf:type <y> 'belongs' neither to <ng1> 
nor <ng2>.
Furthermore, for good operational reasons, no truth maintenance 
information is preserved. The inferred triple (which may have 
justifications via several paths through the rules) is simply marked 
'inferred'.
Note that the rule language does allow triples to be inferred into other 
named graphs, but these are used only as internal (e.g., for the 
housekeeping of induction over lists) and are not exposed to the query 
interface.
Barry
link

answered 03 Apr '13, 11:02

Discussion-Board-Archive's gravatar image

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

Date: 2012-09-28 16:23:07
From: stellato@info.uniroma2.it
Dear all,
this makes me raise another question: is there any specification in the
RDF-world about relationship between inference and named graphs, which maybe
I'm missing and which I can be pointed to?
that is, apart from what Sesame2 technologically exposes and how it
organizes knowledge (e.g. the inferred triples are stored in the unnamed
graph), should we expect that there is any shared semantics on the use of
inference over NGs? So that we can even tell if Sesame2 is compliant with it
and to which extent it covers the specification.
Beyond the paper: "Named Graphs, Provenance and Trust" (Carroll, Bizer,
Hayes, Stickler) , which I read years ago and which gives hints on how NGs
can be used for different purposes, I saw nothing stating anything
"definitive", such it would be the case for a W3C document.
I'm curious, for instance, if it ever makes sense to desire to reason only
about a subset of the NGs in a dataset, or to store the triples inferred so
far in a given NG instead of the "unnamed" one, and how to declare this
thing somehow so that any machine accessing the dataset can understand
that...and many more questions like these ones.
Best,
Armando
link

answered 03 Apr '13, 11:02

Discussion-Board-Archive's gravatar image

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

Date: 2012-10-03 09:18:58
From: antoine.zimmermann@gmail.com
Thank you for the answer.
So, if I understand you correctly, there will be in the unnamed graph
the inferred triple:
<b>  rdf:type  <Y>
but will there be anything else with my example? And what if the example was:
<ng1> {  <X>  rdfs:subClassOf  <Y> .  <a>  rdf:type  <X> }
<ng2> {  <Y>  rdfs:subClassOf  <Z> .  <Z>  rdfs:subClassOf  <T> }
This will produce the triples "<b> rdf:type <Y>." and "<Y>
rdfs;subClassOf <T>." in the unnamed graph, right? But these two
triples further entail "<b> rdf:type <T>." Will this last triple be
materialised too in the unnamed graph?
Best,
AZ
link

answered 03 Apr '13, 11:03

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
×243
×16

Asked: 03 Apr '13, 11:02

Seen: 1,541 times

Last updated: 05 Dec '16, 02:20

powered by BitNami OSQA