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Re: Why do you want to do that?

From: Pat Hayes <phayes@ihmc.us>
Date: Mon, 11 Aug 2008 23:15:15 -0700
Message-Id: <p06230926c4c6d98cf0d4@[]>
To: "Richard H. McCullough" <rhm@pioneerca.com>
Cc: "Frank Manola" <fmanola@acm.org>, "Adam Pease" <adampease@earthlink.net>, "Semantic Web at W3C" <semantic-web@w3.org>, "KR-language" <KR-language@YahooGroups.com>

At 10:56 PM -0700 8/11/08, Richard H. McCullough wrote:
>I finally got a few minutes to read OWL Guide 3.1.3
>I read that section as supporting my position.  The word "context" 
>is mentioned
>several times, with the implication that X ismem IndividualSet; in 
>one context,
>and X ismem ClassSet; in a different context.

Is that actually asserted anywhere? Please give a citation.

>But a problem arises because OWL doesn't have contexts.
>So, apparently, the OWL solution to mix all contexts together,
>and ASSUME that all the propositions are still true.

No. The OWL methodology, like that of virtually all modern logic, is 
to define a formal semantics for the notation, which then DETERMINES 
what is true and false. There are no assumptions anywhere. So there 
isn't a problem. And there are no contexts in OWL as it isn't a 
context-dependent language.

>To make this problem more apparent, we can specify the contexts
>    at view =  ind { X ismem IndividualSet; };

What does that mean? What is the semantics of your formalism? Because 
if you were to provide one, that would stop all the argument, by 
answering the question.

>    at view = cls { X ismem ClassSet; };
>The question is: what happens when we mix the two contexts together?

What DETERMINES what happens? How is consistency defined for your formal logic?

>Pat Hayes says
>    at view = mix { X ismem IndividualSet; X ismem ClassSet; };

No, I didn't say that, as I don't speak this language. I wrote in English.


>Dick McCullough says
>    at view = mix { not{X ismem IndividualSet;}; X ismem ClassSet; };
>Dick McCullough
>Ayn Rand do speak od mKR done;
>mKE do enhance od Real Intelligence done;
>knowledge := man do identify od existent done;
>knowledge haspart proposition list;
>----- Original Message ----- From: "Frank Manola" <fmanola@acm.org>
>To: "Richard H. McCullough" <rhm@pioneerca.com>
>Sent: Friday, August 08, 2008 9:01 AM
>Subject: Re: Why do you want to do that?
>>On Aug 8, 2008, at 11:21 AM, Richard H. McCullough wrote:
>>>Over the last six years, I have suggested a number of
>>>"improvements" to the RDF language.  Not one of
>>>my suggestions was adopted.  Apparently,
>>>RDF is fine just the way is, thank you!
>>Yep.  That doesn't imply opposition to improvements though;  some 
>>people think the way to provide the "improvements" they want is to 
>>define languages "on top of" RDF (like the OWL dialects) rather 
>>than  making those changes directly in RDF.  That way, your 
>>"improvement"  and my improvement can possibly co-exist more nicely 
>>>I would now like to turn the tables, and ask
>>>why do you want to do that?
>>>I'll start with two features of RDF which seem to be popular.
>>>1. X  subClassOf  X;
>>>A neat mathematical property, right?
>>>But if you do the inferences, what it means is
>>>   X  sameAs  X;
>>>We already knew that.
>>>Why do you want to do that?
>>I need some help with this question.  Do you think being able to 
>>say X subClassOf Y is OK?  If so, are you asking why RDFS (not RDF, 
>>BTW) doesn't explicitly forbid the special case of X subClassOf X? 
>>Why do  you want to do that (i.e., test for this special case all 
>>the time)?   Or are you asking why people *write* X subClassOf X?
>>>2. X  type  Y;  X  subClassOf  Z;
>>>Another neat property: X is an individual and a class.
>>>Now I can ... What?  I don't know.
>>>Why do you want to do that?
>>How about the example in Section 3.1.3 of the OWL Guide?

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Received on Tuesday, 12 August 2008 06:16:19 UTC

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