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Re: [Linking-open-data] watchdog.net and LOD best practices

From: Frederick Giasson <fred@fgiasson.com>
Date: Thu, 17 Apr 2008 09:32:41 -0400
Message-id: <48075179.4050005@fgiasson.com>
To: Matthias Samwald <samwald@gmx.at>
Cc: public-lod@w3.org, Kingsley Idehen <kidehen@openlinksw.com>, Alan Ruttenberg <alanruttenberg@gmail.com>

Matthias Samwald wrote:
>
>> Even if the description of a "resource" in the URI rfc say
>> that it can refers to actual "things", we only have their RDF 
>> representations.
>
> The fact that we might only be able to retrieve RDF through the web 
> does not mean that the URI http://example.org/eiffel_tower cannot 
> designate a physical object. Please elaborate.

No just in relation with the Web. Practically speaking, the Web is only 
a way to communicate the RDF description of this resource. I Could send 
you a letter where I wrote all the RDF+N3 that you can transcript and 
put in your triple store. I don't need the Web to publish RDF... but 
hell, the Web is an easy way to communicate this kind of stuff :)

So, what this mean? This mean that in a RDF World only (see it as a 
triple store on an un-connected computer (un-connected to any kind of 
network)), you are still manipulating RDF representations of Things.
>> Well, what is a Class and what is an Individual of a Class? The line 
>> is gray, and and someone's class will be another person's individual.
>
> Example: An individual of a tower exists at a certain place at a 
> certain time (e.g., the Eiffel tower is currently located in Paris). 
> The class of towers is 'made up' of a multitude of towers at many 
> times and places. It is very easy to distinguish class from individual 
> when looking at physical objects. Of course, making such distinctions 
> gets much harder with more abstract things such as 'concepts' or 'data 
> objects'. Which, in turn, makes it harder to know where to place 
> relations such  as owl:sameAs, or to create ontologies that enable 
> automated reasoning and consistency checking. This is why I am a bit 
> critical about using such abstractions as the foundations of a large, 
> hopefully somewhat coherent Semantic Web. The identity between 
> resources named by URIs and shared semantics are the nodes that hold 
> everything together. If they are too loose, everything starts to drift 
> apart, and meaningful data integration on a large scale becomes 
> impossible.

Sure that some example are clearer than others. But there are always 
this gray line that can easily be one thing or the other :)

But one thing I say is: we *have to* try to make it as coherent as 
possible. But I fear that the semantic web won' ever be coherent. This 
is a characteristic that we have to work with, to assess, in order to 
create value out of this incoherent World :)

>> There are certainly best practices such as DOLCE and BFO, but these 
>> are not sacred books, and different usecases will have an hard time 
>> on them.
>
> DOLCE and BFO are foundational ontologies, not practices. The question 
> is: should using such foundational ontologies become a practice?
>
>> But since we are in a Web of Representations, there will be errors 
>> and inconsistencies (there are on the Web, and there will be on the 
>> Semantic Web)...
>> And this is normal: my representation of the World, is not the same 
>> as your Representation of the World.
>
> Probably true, and this is why 'representations' are not very useful 
> for data integration. We need to postulate the existance of an 
> external reality before we can actually talk about errors and 
> inconsistencies.
>
> Many of us are mixing up questions of epistemology (how we as persons 
> can gain knowledge) with questions of ontology (how things are in 
> reality). I emphatically agree with your subjectivist / constructivist 
> approach towards epistemology -- the way I perceive the world might be 
> very different from the way you perceive the world. However, the 
> differences in our cognitive representations while watching the Eiffel 
> tower do not lead to the existance of two separate Eiffel towers in 
> reality (ontology).
No, certainly not. But I can "describe" the Eiffel tower with some 
characteristics, where you can "describe" the Eiffel tower with other 
characteristics: two representations (in RDF using different ontologies? 
:) ) of the same "Thing". For example, my URI is a URI of "my" 
description of the Eiffel tower, where your URI is the URI reffering to 
another representation of the same "thing". However, no URI refers to 
the actual "Thing", but only different representations of the same 
"Thing" :)

I do believe that we only refers to "representations" in RDF.

> The human ability to accept the existance of a consensual external 
> reality was a key that enabled the development of science and 
> technology, for testing hypotheses, developing theories and 
> integrating many small pieces of human experience into a coherent, 
> testable and shared view of reality. We should not weaken the 
> practical advantages of this ability by a too radical subjectivism.

But this is just philosophical.... In reality, in my daily working 
life.... I refers to objects that have properties. I don't care if one 
name it an infroamtion resource, a web document, a Thing, etc. What I 
check is: is this URI in one of my triple store? No? Then can I resolve 
this URI on the web? yes? Is there RDF? Yes? Is this RDF describing this 
URI? yes? then lets do something with it!

I want to do something usefull (even if not perfect) with these things!


Take care,


Fred
Received on Thursday, 17 April 2008 13:35:59 UTC

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