Is it possible to create a rule across 2 models?

Question

Is it possible to create a rule across 2 models? I added Jack as a creator of an articles in articles model and then I added a row to make creator a subclass of person. So now I'm trying to query across 2 models. I was trying the following query. Give me the grandfather of the author of the article with the title ERNIEX
SELECT m grandfater, c creator, t title
FROM TABLE(SDO_RDF_MATCH(
'(?t :title "ERNIEX") (?m fam:grandParentOf ?c)',
SDO_RDF_Models('articles2', 'family'),
SDO_RDF_Rulebases('RDFS', 'family_rb'),
SDO_RDF_Aliases(SDO_RDF_Alias('','http://purl.org/dc/elements/1.1/'), SDO_RDF_Alias('fam','http://www.example.org/family/')),
null));
When I run the query about I get the error
ORA-20000: We do not have a valid rules index for this Model-Rulebase combination
So I thought to create a index but I'm not sure how. I tired the following code but I think I'm doing something wrong. Can anyone point me in the right direction. Or for that matter does anyone know of a more extensive tutorial to using the database? Thanks
BEGIN
SDO_RDF_INFERENCE.CREATE_RULES_INDEX(
'rdfs_rix_articles2_faily',
SDO_RDF_Models('family', 'articles2'),
SDO_RDF_Rulebases('RDFS','family_rb')
END;
Ernest Lim

Answer 1

You are right, a rules index would have to be created for the rulebases and both the models you use in the query. The example in the rules index creation you have shown at the end of your post does exactly that - creates a rules index for the set of rulebases and models: RDFS, family_rb, family, articles2. Once that rules index is created you should be able to run the query without getting the error.
Did you get an error while trying to create a rules index using the code shown in your post?
FYI, a forum for posting semantics questions is at RDF Semantic Graph