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[ontolog-forum] Fwd: Distributed Knowledge?

To: "ontolog-forum" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Len Yabloko" <lenya@xxxxxxxxxxxxx>
Date: Wed, 15 Oct 2008 23:09:50 +0000
Message-id: <W121497641112591224112190@webmail11>
>> Pat,
>> You answer makes clear how Semantic Web is supposed to operate.  
>> However, it seems to leave very important practical consideration  
>> outside of its scope.
>Can you elaborate?    (01)

Sure. The most important to me consideration and the one I was asking you about 
is how to negotiate assumptions in order to complete required inferences. Did I 
miss your answer to that questions?     (02)

>> SB>>     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.
>> I strongly agree. There are implicit assumptions behind any  
>> inference which are not part of any specification.
>No. That is the whole point of the semantic web, and why it is based  
>on a monotonic system of logics. 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.    (03)

I think some assumption are always left implicit. How can anyone do that job 
properly? Do you?    (04)

 However, you are not required to publish the  
>conclusions themselves: the process of drawing the conclusions is up  
>to the reader. And a reader may, of course, input content from many  
>sources and hence be able to draw other conclusions which you had not  
>anticipated.    (05)

I was asking not about unanticipated conclusions, but about assumptions. Nobody 
need to anticipate all conclusions, but some assumptions must not be 
contradicted or should be negotiated (ie accepted or rejected).    (06)

>> If one wants to apply Semantic Web to a particular problem, then  
>> some of these assumptions must be evaluated with respect to the  
>> problem domain. Or are you suggesting that assumptions implicit in  
>> SW core meta-theory
>I am not sure what you mean by 'core meta-theory'. The nearest  
>interpretation which makes sense woul dbe the specifications of the  
>actual logics involved (RDF, RDFS, OWL, etc.) and their semantics. If  
>this is what you mean, then yes, indeed...
>> are never in conflict with any problem domain,
>... that is being assumed. The logics themselves are indeed 'domain- 
>neutral'. They can be used to describe any topic under the sun.
>> as long as the problem defined in terms of the same meta-theory? In  
>> that case we are forced into Closed World Assumption which may not  
>> be practical for distributed knowledge.
>No, we are not forced into a closed world assumption. I have no idea  
>how you came to this conclusion.
>    (07)

Very simple: agent interaction in most cases are conducted on basis of 
incomplete information. Therefore in the absence of any contradiction to the 
initial assumptions agents indeed treat those as true. For example if you pay 
with credit card then bank is assuming that you will pay back to the bank. 
Isn't financial system then based on Closed World Assumption? If Semantic Web 
does not offer any mechanism for negotiating assumptions, then every 
transaction is based on CWA.    (08)

>> PH>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.
>> But what if one can not draw necessary conclusions to do the job -  
>> where do we go from here?
>Then the agent in question is not able to use the semantic web, ie it  
>is in the same position as all agents were before the SWeb was created.
>    (09)

Which basicaly renders SW useless for most practical purposes (unless augmented 
with negotiating mechanism)    (010)

>> Does SW offer any means for negotiating additional required  
>> knowledge to make further inferences?
>Any agent, even yourself, can of course go looking on the Web for  
>additional knowledge. That is pretty much what the Web is all about,  
>after all. There are aids to such a search, such as Swoogle.  Most  
>interesting SWeb applications use knowledge from multiple sources in  
>this way.  It is of course much more efficient if you already have  
>some idea where to look.
>    (011)

May be that is what SW is all about, but certainly not the Web. Today it is 
about doing business online, - not about posting ontologies.    (012)

>> SB>> 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?
>> I think that is the question of great practical significance. The  
>> "level of misunderstanding" can be replaced with more formal  
>> criteria based on specific conclusions that could not be made. Then  
>> some of initial assumptions can be revised and resulting "damage"  
>> assessed to answer the second question.
>Welcome to the semantic web. I suggest reading some of the now quite  
>extensive technical literature before expressing any more views in  
>public.    (013)

Thank you for welcoming me to (your) semantic web, but I am not sure I want to 
come in.     (014)

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