RE: minor naming quibble

> 
> > owl:differentIndividualFrom   -->  owl:different (or owl:differentFrom)
> 
> I prefer owl:differentFrom.
> 
> 

Presumably generalised to classes and properties.

P1 differentFrom P2 .
P1 rdf:type  owl:Property .

entails

exists a,b
  s.t. a P1 b .
and not a P2 b .

(how do I say that in OWL?

Maybe 

_:a rdf:type {
Symmetric difference of
<<Restriction P1 hasValue _:b>>
<<Restriciton P2 hasValue _:b>>
}.

)

C1 differentFrom C2 .
C1 rdf:type owl:Class .

entails

the symmetric difference of C1 and C2 is non-empty.

(I can see how to say that in triples, but it's fairly long winded).