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Re: [ontolog-forum] brainwaves (WAS: to concept or not to concept, is th

To: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Patrick Cassidy" <pat@xxxxxxxxx>
Date: Wed, 12 Dec 2007 21:07:28 -0500
Message-id: <023001c83d2c$e9fd0df0$bdf729d0$@com>

The issue of what to do with existential qualifiers is important, and the answer, I think, will have to depend on how the ontology is going to be used, and how big it is.


For my purposes I categorize existential qualifiers into  four categories:

(1)     Informative: the assertions are in the ontology only in effect as documentation, for a human to read and to provide an unambiguous human-interpretable definition of the intended meaning of the term, but the logical implications are never used by the machine (never!)

(2)    Advisory: one is allowed to enter data for individuals without entering data for the implied individuals, but at data entry time the machine provides a warning that there is a missing implied individual, but does nothing.  The existential may or may not be used in reasoning.

(3)    Supplementary; if no individual that satisfies an existential qualifier exists at data entry time, the system creates one, of the most specific implied Type, and provides a warning.

(4)    Required:  if no implied individual exists at data entry time, the system refuses to accept the input data.


In case 2, the system may or may not create implied individuals at query time.  If the system is at all large, creating those individuals  may result in an avalanche of skolemized individuals generated, making the results hard to interpret, and the time to completion very long.  If the system is not too large, this may be tolerable. 


The Ontology Works IODE system provides the option to make an existential (they consider them as “integrity constraints”) either advisory (2), and not used at query time, or critical (4) , refusing to load if the constraint is violated.  This conforms to the Database practice of using integrity constraints on data.   I find the IODE system more effective than any other (of a small list) that I have tried.  Nice system – but, alas! expensive.


  I think that OWL falls into the (2)(not used) category; they don’t cause any problems in reasoning.  But Protégé will put a red box around any relation widgets having missing implied individuals – essentially, just advisory, and that’s their warning mechanism.  The OWL validator (“vowlidator”) will also catch missing implied individuals and provide a warning.


   I think there is a place for each of these existential statement types, but managing them (other than (1), which I think can be very useful) may be complex for full first-order systems.  I would be interested in the thoughts of others on the topic.




Patrick Cassidy



cell: 908-565-4053



From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of jayanosy@xxxxxxxxxxxxxxxxxxx
Sent: Wednesday, December 12, 2007 5:01 PM
To: [ontolog-forum]
Cc: [ontolog-forum]; ontolog-forum-bounces@xxxxxxxxxxxxxxxx
Subject: Re: [ontolog-forum] brainwaves (WAS: to concept or not to concept, is this a question?)


Back to reasoning about knowledge using logic and semantic interpretations, ala, for example using the OWL language.

 I have the question regarding the existential quantifier when applied as a restriction to a property between individuals in two different classes. (There must be at least one individual in the range class for the property associated with the domain class for each member of the domain class.)

It would seem that in a situation where knowledge about individuals (in the ontology) is gathered over time, there is some complex balance between the number and type of property existential restrictions that must be satisfied for individual membership in a class to ensure both appropriate classification and inference across the model, and the need to capture knowledge while it is gathered.

My question is "Does the use of an existance quantifier in an OWL ontology restrict the entry of individuals for a class when there is insufficient knowledge of other individuals that satisfy the existential restrictions on properties for that class?

or restated

We have partial knowledge about an individual, a, and have problem with capturing it in an ontology with existential restrictions..

If  an OWL ontology is used subsequently to develop a knowledge base of facts, and there are multiple Existential restrictions on properties between classes, in the case of partial knowledge about an individual in the domain of a property , I have the following options:

  1.  I cannot enter an individual for a class in a knowledge base unless I have knowledge about all individuals in the range classes that satisfy the necessary existential restrictions on properties for the domain class
  1. I add the individual for a class in a knowledge base even though there is not sufficient knowledge of other individuals in other classes to satisfy all necessary existential property restrictions

The PROS and CONs appear to be

1 PRO  - the knowledge base is consistent and only has individuals that satisfy all criteria of the ontology model, all individuals in the knowledge base are correctly classified according to the model
1 CON - there is lost knowledge since the partial knowledge about an individual was not entered into the knowledge base

2. PRO - partial knowledge about an individual is captured in a knowledge base
2. CON - individuals are entered in the knowledge base that do not satisfy all model criteria, these individual may be incorrectly classified with partial knowledge, results of reasoning may be ambiguous?

Is it possible to define an ontology where individuals can be entered in more general classes with fewer existential property restrictions, and as knowledge about other individuals is discovered and are entered, we may have the case where the original individuals entered in more general classes may now satisfy  the more existential property restrictions for specialized classes. Is there a way for this membership in more specialized classes to be automatic inferred as data is entered instead of having to create an additional entry?

If the answer is yes than I can see a pragmatic way to define an ontology that will automatically specialize the classification of individuals, from more general classes, as more knowledge is added to the knowledge base.

Is this reasoning correct?


Best Regards,
John A. Yanosy Jr.

Cell: 214-336-9875
PH: 972-705-1807
Email: JAYANOSY@xxxxxxxxxxxxxxxxxxx

Pat Hayes <phayes@xxxxxxx>
Sent by: ontolog-forum-bounces@xxxxxxxxxxxxxxxx

12/12/2007 12:58 PM

Please respond to
"[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>


Duane Nickull <dnickull@xxxxxxxxx>


"[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>


Re: [ontolog-forum] brainwaves (WAS: to concept or not to concept, is this a question?)


>On 12/10/07 8:35 AM, "Christopher Menzel" <cmenzel@xxxxxxxx> wrote:
>>  Well, I obviously can't deny that you *experience* something, but
>>  until you can come up with some reasonably hard data rather than
>>  feelings and anecdotes, I don't think you've got any real
>>  justification for your belief that there's anything more than
>>  coincidence involved.
>Which leads us into ....
>Probability and statistics!
>I am surprised this group has never had a discussion on this topic or had
>someone present on P&S (irony - there is a chance I might be wrong).  For
>some scientific axioms, tenets, etc. there seem to be a search for proof by
>verifying that the one universal truth is not mere coincidence.  For
>example, if I state here are 10 random numbers and give you these:
>You really don't know if they are truly random.  Knowing how they are
>generated helps ( for example - knowing how the Java.Math.Random class works
>and the core algorithm is written and run on the metal) but other than that,
>there  is no verification that these are truly random.  The chance they are
>random is equal with every other possible 10 random numbers.
>So what does a scientist do?  Observe until they are reasonably satisfied
>there is a norm or baseline then look for statistical anomalies?  Isn't this
>somewhat flawed too since we can never really be 100% sure we have truly
>tested everything?  I got into an argument with a friend last weekend over
>the existence of god.  He stated that since there is no positive evidence
>god exists, it proves there is no god.  His inference takes a quantum leap
>in logic obviously as what it really means is that god's existence cannot be
>scientifically verified.  God may exist or may not exist was my position.
>So how does this conflict with the topic of the thread.  The experience that
>you think of someone and they call you?  Statistically, unless it had been
>studied (I am sure it has

indeed it has, extensively and rigorously. And
no, repeat, NO, claims of telekinesis or
telepathy have ever survived experimental test.
That is, the claimed phenomena are either
undetectable or are no more probable than chance.

So, as you say, back to the topic of this thread.
Chris did not say that there was any PROOF that
some humans are not superhuman in some way. What
he said, and he is absolutely correct, is that
there is no REAL JUSTIFICATION for such a belief.
One can believe anything, and protect that belief
with a suitable irrational explanation. (The
reason you can't see the little green men pushing
the protons around is that they hide before you
can shine a light on them. The reason there are
fossils is that God put them there to test our
faith. Etc.) The resulting system of beliefs is
probably impossible to refute, but that does not
make it any more rational to believe it, or
provide any justification for not rejecting it as

>), there is a small but real probability than some
>human beings have capabilities beyond our perceptions.

And the reason they have never shown up is that
they are so rare that nobody has captured one yet
to put them into a laboratory? Or do their
capabilities mean that they can see the white
coats coming and avoid them?

>  Just like my friend
>stating "it proves god does not exist", the correct statement is probably
>more along the lines of "telekinesis has not been scientifically resolved to
>a point where it can be satisfactorily quantified"

Er...no. The correct statement is that
telekinesis has never been reliably observed: as
far as anyone can tell, there is no such thing as

>.  It does not mean it
>does not exist or is not real.

It strongly suggests it is not real. On what
basis would anyone insist it was real, if there
is no evidence for it, and repeated attempts to
find such evidence have failed? At what point
will one conclude that this search seems to be a
waste of further time?


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