>   >  Question 4: Is there any kind of inference going on when retrieving
>   >  things from DBpedia so I can asume some things? (for example, that all
>   >  writers are also persons, etc) Is there a way to refine this rules to
>   >  add support for better inferences or better awareness of cross-onthology
>   >  classification? In the portuguese case, it seems to me easier if there
>   >  is way to say "all the things being skos:subject
>   >  <http://dbpedia.org/resource/Category:Portuguese_writers>   are also
>   >  dbpedia-owl:Writer" than to try to edit one by one the articles so they
>   >  end up being explicitly dbpedia-owl:Writer .
>
> Responding to myself, I found this on the matter of inference/reasoning
> and categories:
>
> http://stackoverflow.com/questions/3300191/sparql-skosbroader-help
>
> Haven't tried that yet, but I hope there is (or there will be) a more
> concise way of achieving the same.

Inference is performed in backward-chaining fashion and optional.

The DBpedia linksets are sometimes derived from a forward-chaining 
inference workflow.
> Still wondering if there is *ANY* inference going on in the process of
> quering DBpedia, and (if any) who and when it is done (when quering in
> the rdf store, when mapping wikipedia so it all becomes explicit and
> later there is no need for inference, etc).

Only if inference context is enabled which is done by specifically using 
SPARQL pragmas to apply inference rules to SPARQL patterns.


There are some pre-configured inference rules associated with the 
DBpedia instance which are visible via the interface at: 
http://dbpedia.org/fct . When you get the description of an entity, you 
can use "Settings" to select inference rules from a drop-down etc.. The 
inference rules names can also be used in your Virtuoso SPARQL Query 
pragmas.

Links:

1. 
http://virtuoso.openlinksw.com/presentations/SPARQL_Tutorials/SPARQL_Tutorials_Part_2/SPARQL_Tutorials_Part_2.html
 
-- Virtuoso SPARQL Tutorial with Inference Rules Coverage

2. 
http://virtuoso.openlinksw.com/presentations/SPARQL_Tutorials/SPARQL_Tutorials_Part_2/SPARQL_Tutorials_Part_2.html#(41)
 
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-- 

Regards,

Kingsley Idehen 
President&  CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen






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