- From: Bijan Parsia <bparsia@cs.man.ac.uk>
- Date: Mon, 19 Nov 2007 23:49:34 +0000
- To: "Mauro Mazzieri" <mauro.mazzieri@gmail.com>
- Cc: "Jun Fang" <leon.essence@gmail.com>, semantic-web@w3.org
On Nov 19, 2007, at 2:14 PM, Mauro Mazzieri wrote:
>
> 2007/10/29, Jun Fang <leon.essence@gmail.com>:
>> I am new to the Description Logics. I have met the following problem.
>>
>> As we know, K |= C <==> C unsatisfiable with K,
>> here K is a DL knowledge base,
I.e., a set of *axioms*.
>> and C is a concept
>>
>> If K is set to {A,B},
That's not a set of axions.
>> and C is set to (AȁB),
I.e., ~A v B
>> then C is unsatisfiable with
>> K
I don't see why. The TBox is empty afaict. Thus ~A v B is satisfiable.
> C is incoherent with K: is a concept that can not have instances.
Why? What do you think K is?
> Toghere with ex. C(a) we have an inconsistent ontology.
>
>> it means K|=A subclassof B
>>
>> using the similar way, we can also get K|=B subclassof A,
Doesn't work for me in the same was as above. Did something get munged?
>> I must be missing something obvious here. Can someone can tell me
>> the reason
> As they're defined, A and B are the same class.
[snip]
You think "K is set to {A, B}" means "K = {A<->B}"? Ok. But, uh, if
A<->B, then A->B and B->A....and neither is incoherent.
Jun, try downloading Protege4 or something similar and playing with
real ontologies and a reasoner. I find it helps.
Cheers,
Bijan.
Received on Monday, 19 November 2007 23:54:39 UTC