Value restriction on properties and reasoning

[lesire]

Hi,
I have made a small ontology to test Owlready2 for a robotic project in my lab. I have defined a Resource class, and a UnaryResource subclass, with the has_capacity int property. I have declared UnaryResource to be equivalent to Resource and has_capacity.value(1). After a call to sync_reasoner, an instance declared as a Resource with 1 capacity is correctly reparented to UnaryResource, but I would also expect the inverse, i.e. an instance declared as a UnaryResource to have a capacity set to 1! What am I missing?

A code snapshot is following. (and my .owl file is initially empty)

Thanks,
Charles

onto = get_ontology("file://./{}.owl".format(name))
onto.load()
with onto:
    class Resource(Thing):
        pass
    class UnaryResource(Resource):
        pass
    class has_capacity(DataProperty, FunctionalProperty):
        domain = [Resource]
        range = [int]
    UnaryResource.equivalent_to = [Resource & has_capacity.value(1)]
motor1 = onto.Resource("motor1")
motor1.has_capacity = 1
motor1.is_shareable = False
battery = onto.Resource("battery")
battery.has_capacity = 24
battery.is_shareable = True
motor2 = onto.UnaryResource("motor2")
close_world(onto)
sync_reasoner()
print(onto.UnaryResource.get_class_properties())
print(battery, battery.has_capacity)
print(motor1, motor1.has_capacity)
print(motor2, motor2.has_capacity)

[Jiba]

Hi,

If you want to infer data property values, you need to use the Pellet reasoner (Hermit does not support this) and to add the "infer_data_property_values" optional argument (by default Owlready performs only classification). For example:

sync_reasoner_pellet(infer_property_values = True, infer_data_property_values = True)

I've tested it successfully with your example,
Jiba