Replace current super class of an individual with the inferred superclass

Greetings Professor Ignazio Palmisano,

Kindly i have a question in regards to owl-API V5

Scenario:

I have an owl ontology that contains some individuals and some defined classes (has equivalent axioms).

i add a new individual "X" as a subclass of Thing, and i add the individual properties.

i initialise the reasoner and precomputeInferences()

Goal:

if the new individual "X" was classified under an existing defined class, i want to retrieve this inferred class and replace the current individual superclass Thing with the inferred superclass.

Main question:

1) Kindly what is the best way to do this?

Sub question:

2) do i have to save the new inferred ontology and then deal with it as asserted, in order to retrieve that class? i do not like to do this since my interest is only to replace the current individual superclass with the inferred superclass.

i was trying to find how to do this, i came across: EntitySearcher.getTypes(OWLIndividual, OWLOntology), however this retrieves only the original asserted superclass not the inferred.

Thanks for your time.

Sincere regards.

Solution

In order to replace the asserted class with the inferred one (or ones - there might be more than one), you need to do the following:

Retrieve the inferred types
Remove asserted types
Add inferred types

So, called r the OWLReasoner instance, i the OWLIndividual, t its original type and T the inferred type:

OWLOntology o = ...
OWLReasoner r = ...
// This returns the node of direct types - i.e., the set of equivalent classes that are the most specific named types including i among their instances
// This will always be a Node even for a single class. If the reasoner can infer that there are equivalent classes, they all will appear in the Node
Node<OWLClass> types = r.getTypes(i, true);

// remove existing type assertions
o.removeAxioms(o.getClassAssertionAxioms(i));

// add the new ones
OWLDataFactory df = ...
Stream<OWLAxiom> axiomsToAdd = types.entities().map(T->df.getOWLClassAssertionAxiom(T, i));
o.addAxioms(OWLAPIStreamUtils.asList(axiomsToAdd));

Now o contains the new assertions in place of the old ones. Save or further elaborate the ontology as needed.