Re: Question about a logical inconsistency

On 4 Mar 2018 5:13 pm, "Bijan Parsia" <bijan.parsia@manchester.ac.uk> wrote:

On 4 Mar 2018, at 17:07, Dan Brickley <danbri@danbri.org> wrote:

On 4 Mar 2018 07:32, "Bijan Parsia" <bijan.parsia@manchester.ac.uk> wrote:

First, without an individual or Top, you aren't going to get an
inconsistency. An unsatisfiable class, sure. An inconsistency, no.


On Mar 4, 2018, at 15:03, Leila Bayoudhi <bayoudhileila@yahoo.fr> wrote:

Hi,
In the literature, I found that this set of axioms may cause an
inconsistency, though I am not convinced.
SubClassOf(C1 C2)
SubClassOf(Ci C1)
SubClassOf(Cj C2)
DisjointClasses(Ci Cj)


I don't know why anyone would say that this is inconsistent. It's not even
incoherent (ie all the classes are satisfiable).

Maybe you transcribed it wrong?



something like

SubClassOf(Organization, Agent)
SubClassOf(GovtOrganization, Organization)
SubClassOf(Person, Agent)
DisjointClasses(GovtOrganization,Person)

...seems sensible enough (which is no guarantee of anything :)


Disjoint children (and thus descendants) of a class is a normal and desired
modelling pattern! Protege has a button to force this on new hierarchies!
We have disjoint union as a construct!



I think Tom is missing.
Tom is a GovtOrganization.
Tom is a Person.
Tom exists in a parallel universe where its types are not declared disjoint.

I.



Cheers,
Bijan.