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Re: [ontolog-forum] Distributed Knowledge?

To: <phayes@xxxxxxx>, <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Sean Barker" <sean.barker@xxxxxxxxxxxxx>
Date: Wed, 15 Oct 2008 21:03:09 +0100
Message-id: <7DAED7A47B29494BB82C2A3E6373B029@PackardDesk>
 Comments on comments

From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Pat Hayes
Sent: 14 October 2008 19:59
To: [ontolog-forum] ; Sean Barker
Subject: Re: [ontolog-forum] Distributed Knowledge?

On Oct 14, 2008, at 1:23 PM, Sean Barker wrote:

    The question was about what are the expectations of the terms in an ontology. The Semantic Web version seems to suggest that you just pick up on the terms that you are interested in, and that's enough. However, if the term is just the start of a chain of inference, then someone reading only the term will mis-understand the term, at least to some extent. In principle, to understand the term in the way that it is meant, one should follow the inferences which the sender has made, and probably with the same inference engine - hence the need for omniscience.
Let me clarify the idea of the semantic web, as this is exasperatingly close but misses the crucial insight. First, its not necessary have the same inference engine; only an engine which conforms to the published specs, all of which have been carefully and consciously written so as to NOT commit to a particular engine, but instead only to a common semantics. Any engine which draws valid inferences according to the published semantics is acceptable.  
SB> Agreed, but I had been advised that in practice different engines may give different results, particularly if one is forward-chaining, the other backward chaining. Is there any process of certifying an inference engine actually performs as specified?
 Second, its not necessary to have all the inference chains in order to understand the content. That is the whole point of inference: you can do it for yourself, with confidence. If I send you some SWeb content and you draw valid conclusions from it, then those conclusions are just as much part of what I have sent you as if I had sent them directly. You have a blanket licence, provided by the published specifications of the notations themselves, to draw such conclusions. That is WHY I don't need to send them all to you, you see.  
SB> If the primary source publishes all the the information it infers from, yes. However, the primary source may have made inferences from other secondary sources, and I have not noted in any of the standards any obligation on a source to identify the sources it has also used. Does this therefore oblige the user to search for other sources on the web? And how would the user know what secondary sources had been used by the primary source? It is the assumption that the sources are also active consumers of information rather than passive providers that raises the question of omniscience.
You state in your reply to Len "When you publish some SWeb content, you
take on the responsibility for supplying enough information to enable a
reader to draw the appropriate conclusions. If some assumptions are left
'implicit', then you, the publisher, have not done your job properly."
What is the mechanism for this when you have made inferences from secondary sources?
Copying all the other sources to your content page is surely
the opposite of the way the web works. Conversely, a mechanism to redirect a user
to the other sources would suffer from configuration problems, as the other urces will mostly
likely change over time.
    Alternatively, one might hypothesise that individuals may only pick up on the knowledge they need - use only the terms without further inference. That means that they have, to some extent, misunderstood the term.
No. They can do as much inference or as little as they like. But their not doing so does not imply that they are MISunderstanding anything. They may need only a very limited set of valid conclusions to do their job. That is not misunderstanding.  
SB> Not quite. If correct understanding requires some level of inference, and the user fails to make this inference, then they have misunderstood. If they only need a partial understanding, then agreed it would not be appropriate to call it misunderstanding with respect to their purpose, however, it may still remain a misunderstanding with respect to the source's purpose (an occurrence which many love stories rely on). 
This raises two questions; firstly, how can one quantify the level of misunderstanding? and secondly, how can one then determine if the level of misunderstanding is significant?
    Behind this is my suspicion is that many people start with the assumtion that, say, nouns name things or concepts. An alternative is that nouns are a grammatical category that allow people to play particular word games. Many - but not all - of these games are games that relate to named things or concepts. One problem for ontology development is to exclude from an ontology the nouns which do not name things (are games only) - all though they may have a function in meta-ontology conversations. For example, I would classify "property" as defining one such game. We can cite as properties of a ball its shape, colour, age or cost without suggesting that there is anything in common between shape, colour age or cost (other than being a property). Conversely, the game property rules out "being owned by" or "having followed a particular course" as properties.
Not in the game played in ontology writing, I assure you. Those are just as much properties of the ball as its color is. One of the basic rules of this game is to refrain from drawing 'lines in the sand' like this, as they don't help get anything done and often get in the way.  
SB> The observation was about the habitual use of English, rather than the technical redrawing of the rules for ontology games. If I were to state "It is a property of this ball that it has followed the path from my foot through that window" this would have the pragmatic of claiming that the broken window was not my fault, and the statement would be classified as false. The fact that it may be true for an ontology writer is confirmation that "property" defines a game. The point is not that it is invalid to play such games, but rather, that it is invalid to infer that a word that is used to play a particular game necessarily refers to something in the world which is not a game. 

Pat Hayes
    Further, I suspect most terms in an upper ontology to be word games, that is, that these terms are contexts in which a particular set of metaphysical rules may be applied, where:
Context - an agreement on the things germane to a conversation
Metaphysical rule - a criterion for distinguishing categories within a context - e.g. change is germane to physical objects but not to abstract things like numbers.
(At least Ambrose Bierce might agree).

Sean Barker
Bristol, UK

From: paola.dimaio@xxxxxxxxx [mailto:paola.dimaio@xxxxxxxxx] 
Sent: 14 October 2008 03:27
To: Barker, Sean (UK)
Subject: Re: [ontolog-forum] Distributed Knowledge?

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I am curious what is the preamble for this, or are you just following your train of thoughts?

I have been working on some aspects of distributed knowledge, in particular in relation to my interest in 'expertfinding ',  and I am interested in what you say but of all things , its your conclusion that strikes a chord with me

One might also observe that to base everything on a single, comprehensive
ontology, one would need to be omniscient.

Not necessarily. A single unified ontology can be  a model for omniscience, but individuals (people and machines) only access parts of it at any given time, until and unless , our cognitive apparatus (the way we learn and make inferences) is radically overhauled.  
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