owl

OWL reasoner not recognizing negated restriction?

In following example (written in OWLready2):

    class A(Thing): pass
    class p(ObjectProperty, FunctionalProperty): pass
    class B(Thing): pass
    class B1(B): equivalent_to = [B & p.some(A)]
    class B2(B): equivalent_to = [B & Not(p.some(A))]

    b1 = B(p=A())
    b2 = B()

object b1 is reparented to B1, while b2 is not to B2. What's the reason for that? Did I use the wrong design pattern?

Solution

  • Because of Open World principle its considered unknown whether the defined individual b2 actually has a p=A(). OWLready2 has the means to use close world approach for the individual:

    close_world(b2)

    This will add a p.only(Nothing) restriction to b2, which is sufficient to infer b2 as being of class B2.