Re: "In Defense of Ambiguity"

I enjoyed the Hayes & Halpin paper very much.
If you compare that paper to your original quote re
W3C model theoretic semantics, you will see a
significant change.

Hayes originally talked about the impossibility of
of identifying the correct "possible world" -- which is
the wrong thing to be doing.
In the recent paper, Hayes talks about the inherent
ambiguities in the "real world".  It is a significant step
forward to focus on the real world, instead of possible
worlds.

However, Hayes is still overly pessimistic about the
difficulties of communicating in the real world.  We humans
have been communicating successfully for thousands of
years.  It is not that difficult to shift our communication medium
to the World Wide Web.

The most important feature of the mKR language
(http://mKRmKE.org/) is its representation of the context
of a statement, which provides the means to conquer ambiguity.

Dick
----- Original Message ----- 
From: "Richard H. McCullough" <rhm@PioneerCA.com>
To: "Booth, David (HP Software - Boston)" <dbooth@hp.com>; 
<martin.hepp@uibk.ac.at>; "Giovanni Tummarello" 
<giovanni.tummarello@deri.org>
Cc: "Jonathan Rees" <jar@creativecommons.org>; "Bernard Vatant" 
<bernard.vatant@mondeca.com>; "semantic-web at W3C" <semantic-web@w3c.org>; 
"Earle Martin" <earle@downlode.org>
Sent: Wednesday, July 09, 2008 7:07 PM
Subject: Re: How do you deprecate URIs? Re: OWL-DL and linked data


> I'm glad you brought up Pat Hayes' possible worlds semantics.
> I think that is very important, and very wrong.
> But I don't want to say any more than that, until after I have read
> the paper which you have referenced below.
>
> Dick
> ----- Original Message ----- 
> From: "Booth, David (HP Software - Boston)" <dbooth@hp.com>
> To: "Richard H. McCullough" <rhm@PioneerCA.com>; <martin.hepp@uibk.ac.at>; 
> "Giovanni Tummarello" <giovanni.tummarello@deri.org>
> Cc: "Jonathan Rees" <jar@creativecommons.org>; "Bernard Vatant" 
> <bernard.vatant@mondeca.com>; "semantic-web at W3C" 
> <semantic-web@w3c.org>; "Earle Martin" <earle@downlode.org>
> Sent: Wednesday, July 09, 2008 6:29 PM
> Subject: RE: How do you deprecate URIs? Re: OWL-DL and linked data
>
>
>> Hi Richard,
>>
>> It sounds like we may be talking about different problems, or perhaps 
>> different use cases.  I'll try to clarify what I (and I think Martin) 
>> meant in my comments about owl:sameAs.
>>
>>> From: Richard H. McCullough [mailto:rhm@PioneerCA.com]
>>>
>>> I haven't been following the "deprecate URIs" thread, so
>>> forgive me if I'm being repetitious.
>>> 1. everything is contextual.  But that's no excuse for being
>>> sloppy with meanings.
>>
>> I agree that sloppiness is bad, and did not mean to imply that it should 
>> be sanctioned.  But "sloppiness" is also a value judgement that depends 
>> on the application -- one person's simplicity is another's sloppiness --  
>> and it's important to have strategies for dealing with it when it does 
>> occur.
>>
>>> 2. ambiguity is not inevitable -- it is avoided by clearly identifying
>>> context.
>>
>> It depends what you mean.  If you are talking about determining the real 
>> world referent of a statement (step 2 in slides 5-8 of 
>> http://dbooth.org/2008/irsw/slides.ppt ), then as Pat Hayes has pointed 
>> out several times, completely nailing that down is almost always 
>> impossible.  And trying to pin it down by clearly identifying context 
>> won't help: that merely begs the question of how to unambiguously 
>> identify the context.  See Pat Hayes' and Harry Halpin's paper "In 
>> Defense of Ambiguity":
>> http://www.ibiblio.org/hhalpin/homepage/publications/indefenseofambiguity.html
>>
>> On the other hand, if you are talking about determining the set of 
>> assertions that constrain a statement's meaning within semantic web 
>> architecture (step 1 in slides 5-8 of 
>> http://dbooth.org/2008/irsw/slides.ppt ), then I agree that can be 
>> unambiguous.
>>
>>> 2. OWL:SameAs (like mKR:is) means identical -- two names
>>> (aliases) which
>>> mean the same thing.  Let's not corrupt the meaning of this term.
>>
>> Agreed.  We should not change the semantics of owl:sameAs.
>>
>>> 3. there are other terms which can be used to express varying
>>> degrees of similarity.
>>
>> But owl:sameAs is *exactly* the term needed to indicate that both a:a and 
>> b:b denote the same resource in a statement like this in File1:
>>
>>    a:a owl:sameAs b:b .
>>
>> or that b:b and c:c denote the same resource in a statement like this in 
>> File2:
>>
>>    b:b owl:sameAs c:c .
>>
>> However, that does *not* mean that an application X wishing to combine 
>> the data from File1 and File2 must treat a:a and c:c as denoting the same 
>> resource.  Indeed, doing so may cause a logical contradiction.
>>
>> What's going on?  From the File1 author's perspective, a:a and b:b 
>> denoted the same resource, and from the File2 author's perspective, b:b 
>> and c:c denoted the same resource, but from X's perspective, they may 
>> not.   One may ask, "what resources are a:a, b:b and c:c *supposed* to 
>> denote?", but their definitions may well admit multiple interpretations, 
>> and multiple interpretations are permitted in the RDF semantics:
>> http://www.w3.org/TR/rdf-mt/#interp
>> [[
>> The basic intuition of model-theoretic semantics is that asserting a 
>> sentence makes a claim about the world: it is another way of saying that 
>> the world is, in fact, so arranged as to be an interpretation which makes 
>> the sentence true. In other words, an assertion amounts to stating a 
>> constraint on the possible ways the world might be. Notice that there is 
>> no presumption here that any assertion contains enough information to 
>> specify a single unique interpretation. It is usually impossible to 
>> assert enough in any language to completely constrain the interpretations 
>> to a single possible world, so there is no such thing as 'the' unique 
>> interpretation of an RDF graph.
>> ]]
>>
>> One may be tempted to claim that the File1 and File2 authors overstepped 
>> their authority in further constraining the permissible interpretations 
>> of a:a, b:b and c:c to the extent that they were then able to assert them 
>> as owl:sameAs each other.  In other words, it may be tempting to claim 
>> that those authors should not have further constrained the 
>> interpretations of a:a, b:b and c:c beyond the terms' original 
>> definitions.  But the fact is that virtually *every* assertion involving 
>> the term, beyond the logical entailments of a term's definition, further 
>> constraint the permissible interpretations for that term.
>>
>> So the problem is not that owl:sameAs has been abused, nor is it that the 
>> assertions in File1 or File1 are "wrong".  The problem is that the models 
>> of the world embodied by the assertions in File1 and File2 are mutually 
>> incompatible: they cannot be used together in application X without some 
>> surgery.  And the point of slides 15-17 in
>> http://dbooth.org/2008/irsw/slides.ppt
>> is to describe one technique for performing such surgery when it is 
>> needed.
>>
>> So if indeed "It is usually impossible to assert enough in any language 
>> to completely constrain the interpretations to a single possible world", 
>> as stated in the RDF Semantics, then the logical consequence is that 
>> ambiguity is inevitable, so we may as well get used to dealing with is.
>>
>> On consequence of this is that there is a practical trade-off between 
>> reusability and precision: the more precise a term, the more constrained 
>> it is, and hence the more "likely" it is to be incompatible with other 
>> assertions.  Of course, people do not choose assertions at random, so we 
>> cannot really view this as a simple probability of incompatibility, but 
>> the trade-off is nonetheless real: all other things being equal, more 
>> constraints means less reusability (without requiring surgery, at least).
>>
>> On the other hand, having too few constraints makes a term useless in a 
>> different way, when nobody can figure out what it means.  So defining 
>> good, reusable terms is a balancing act: the best terms are those that 
>> are constrained enough (and in the right ways) to be useful, but not so 
>> tightly as to preclude too many applications.  There is no substitute for 
>> good judgement.
>>
>>
>>
>> David Booth, Ph.D.
>> HP Software
>> +1 617 629 8881 office  |  dbooth@hp.com
>> http://www.hp.com/go/software
>>
>> Statements made herein represent the views of the author and do not 
>> necessarily represent the official views of HP unless explicitly so 
>> stated.
>>
>>
>>
> Dick McCullough
> http://mKRmKE.org/
> Ayn Rand do speak od mKR done;
> knowledge := man do identify od existent done;
> knowledge haspart proposition list;
> mKE do enhance od "Real Intelligence" done;
>
Dick McCullough
http://mKRmKE.org/
Ayn Rand do speak od mKR done;
knowledge := man do identify od existent done;
knowledge haspart proposition list;
mKE do enhance od "Real Intelligence" done;

Received on Thursday, 10 July 2008 05:53:23 UTC