Incremental inferencing questions

Question

I am very confused about how to make incremental inferencing work. Here is what I tried in java code:
Attachment attachment = Attachment.createInstance(new String[]{}, "OWLPRIME",
          InferenceMaintenanceMode.UPDATE_WHEN_COMMIT,
          QueryOptions.ALLOW_QUERY_INCOMPLETE);
graph = new GraphOracleSem(oracle, "mc_model", attachment);
graph.setInferenceOption("INC=T");
The trouble is, when I try to do something like this:
ModelOracleSem oracle_sem_model = new ModelOracleSem(graph);
OntModel model = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, oracle_sem_model);
Individual d = model.createInstance(NS+"New_Individual");
parentIndividual.addProperty(transitiveProp, d);
model.commit();
graph.commit();
The command graph.commit() takes around 5 seconds, the same amount of time it if the entailments are created without incremental inferencing. Is there something I am doing wrong? Can I use the OntModel APIs together with Incremental inferencing or do I have to manually add the statements to the model? BTW, I checked the SEM_APIS change tracking property and it seems enabled and has a timestamp
Edited by: alexi on Nov 13, 2009 7:18 AM

Answer 1

Hi,
It looks like incremental inference is indeed being used. Note that there is some overhead involved with doing incremental and non-incremental inference in general, so even with small models it might take a few seconds to finish. Some of the overhead is caused by the large number of rules in the OWLPRIME rulebase, so if you don't need all of them you can selectively disable some components using the GraphOracleSem.performInference(String components) procedure.
Also, it depends on your dataset. For instance, if you're adding only one triple, but that triple declares some heavily used property to be transitive, then that addition might trigger many additional inferences and updating the inferred graph will take more time.
Regarding OntModel APIs and incremental inference, depends on the loading method you use. Incremental inference works best with incremental loading. Please refer to Section 2.2.9 of the Semantic Technologies Developer's Guide for more details.
Cheers,
Vladimir