Expressing disjunction in property chains.

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Expressing disjunction in property chains.

Rey Segundo Guerrero Proenza
Hi all:

I need to express Property chains as a disjoint expression:

r1 o r2 o r3 --> r

or

r3 o r4 --> r

How do you express that in Protègè 4.1? I supposed to use two separate
expressions was equivalent to conjunction. Consequently I tried to
apply Morgan´s law:

not(a) and not(b) <--> a or b

But It does not work, it is syntactically impossible. Any ideas?

Regards,
--
Rey Segundo Guerrero-Proenza
       http://ginusa.blogdiario.com
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Re: Expressing disjunction in property chains.

Thomas Russ

On Jun 1, 2011, at 11:00 AM, Rey Segundo Guerrero-Proenza wrote:

> Hi all:
>
> I need to express Property chains as a disjoint expression:
>
> r1 o r2 o r3 --> r
>
> or
>
> r3 o r4 --> r

I think that the way you would get disjunction is to have two separate  
subproperty relations.  Each subproperty axiom would be separate and  
would not form a conjunction.

It certainly works that way for non-chained properties.  If you have

    p  subpropertyOf r
    q  subpropertyOf r

then you if either p or q is true, r holds.


> How do you express that in Protègè 4.1? I supposed to use two separate
> expressions was equivalent to conjunction.

That only applies to things like domain and range restrictions, where  
each restriction has to be separately satisfied.  Subclass and  
subproperty axioms are treated as disjuncts.  In fact, you can't have  
a conjunctive subproperty restriction because OWL doesn't support  
property intersection, only class intersection.


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