[protege-user] Unusual Behavior with Self

I'm putting together a small ontology for some training work I'm doing. I
was trying to get examples of different kinds of axioms, property
hierarchies, etc. But I also wanted things like Organizations, employers,
etc.

I created a class called Self_Employed_Person:

Person and has_Employer Self

I have one person (Sam_Spade) who works for himself. But when I added the
axiom to define the Self_Employed_Person class, it made everyone a
Self_Employed_Person. I'm attaching a screen print of some of the reasoner
justifications below. I looked at some examples of using Self and that made
me try:

Person and (has_Employer some owl:Thing) and (has_Employer Self )

And that Worked. But I'm not completely sure why? I think somehow that when
I just had the first definition OWL was inferring that anyone without an
employer (I just added that property so none of the others have values set)
could be self employed and somehow adding the additional axiom that they
had to be employed by some Thing fixed that but it is one of those
frustrating bug fixes where I'm not completely sure I get why it worked.
Any ideas? I'm attaching the ontology, it isn't big. It works now, but if
you change the axiom for self employed person back to removing the extra
"some Thing" axiom it will infer everyone is self employed. Would like to
understand better what is going on here.

Here's the explanation:

[image: Self Employed Bug.png]

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