Re: The meaning of "representation"

Tim Berners-Lee wrote:
>
>
> On 2007-11 -25, at 08:47, Xiaoshu Wang wrote:
>
>> Tim Berners-Lee wrote:
>>> a) The definition in AWW resources "all of their essential 
>>> characteristics can be conveyed in a message" does not speak to 
>>> where you are coming from. You take "essential characteristics" as 
>>> meaning "Properties' rather than " content".  So, not having 
>>> understood that, you are happy to consider Pat to be one.  That I 
>>> think is a problem with that definition.  However, remember natural 
>>> language is an imprecise  tool for making these definitions, and 
>>> efforts is needed on the part of reader as well as writer. An 
>>> Information Resource is information.  Pat is not.
>> I am not, and also won't present to be, a linguist.  But if we were 
>> to replace "properties" with "content"? Will that invalid my argument 
>> and strength yours?
>
> Yes, it would invalidate your argument, using your notation, because  
> C is the content of X.   C, if you like, expresses  the meaning of X. 
> Two representations will then be normally exactly Ca = Cb =C as you 
> say.  (In the case that b is for example a less expressive language,  
> Cb is a subset of C.  In this case, such as my accessing your document 
> on a cellphone which can't do pictures, the system relies on my 
> understanding I might not have got all of it, and if you serve 
> different representations, not all complete, then you as a publisher 
> recognize that and accept the consequences.  This happens for example 
> with image resolution).  But the basic model is that all 
> representations of an information resource convey the same information.
>
>
> In an open world, anything can say anything *about* of  document.   
> Its properties.  I can say the document is X is written by you, is 
> misleading, is interesting, etc etc.    This is all *about* the 
> document, it is not the *content* of the document However one cannot 
> add to the *content* of the document .
> If I server up a representation (say at b) which I maintain is a 
> representation of your document  ( <a> sameAs <b>) bit I add more 
> triples then I am lying, mirepresenting what you said.
I am lost here. So, I created a document 
<http://dfdf.inesc-id.pt/tr/web-arch> but no necessarily its content, 
which can be collectively created by anyone in the web?  What kind of 
intellectual property that I am entitled?  The document, what it is 
then, if without the content?
>
>>  Or, will it help me or others to get an objective definition of 
>> "information resource"?
>> I am not, and also won't present to be, a philosopher. But, what is 
>> an "information"?
>
> Information has been quantified by Shannon, who allows us to measure 
> it and so some math about it.
> You can model it in various ways.  one way is to imagine that I have 
> very little idea of your state of mind, or your situation. Then you 
> you send me information: you publish something I read on the web.   As 
> a result of reading it, I have significantly cut down the 
> possibilities for what I imagine your state of mind to me.
>
>> IMHO, Information is never a static or physical thing.
>
> It is not physical.  It is absutact.  But you can have a very static 
> thing like the RDFS ontology, which is a static set of statements.
>
>>  Information is acquired through a process but not presented as being 
>> is.
>
> You discuss the web as communication system, but that is I think too 
> low a level. It is useful to rise above the level of communication 
> system, and think of it as a word of interconnected documents. It is 
> true that the communication system brings this WWW world into 
> existence.   And we are discussing the details of how that happens.  
> But the goal is to make a web of documents in an abstract space. That 
> is the web.
I felt you are actually strengthening my argument as oppose to weaken it.

First, Shannon quantifies the information to investigate communication.  
This is what I am trying to say that web is a communication system. 

Second, information is embedded in a message, i..e, it is the content of 
the message, yes?  Then, you said the information is abstract, and in 
your previous mail you said that  "However, as the representation is a 
set of bits, its identity is is contents, IMO". The the identity (i.e., 
the resource identified by the URI) is abstract, right?  That is the 
whole point that I want to make right?

Of course, here we have to ask in what sense do we mean by "abstract".   
Plantoist thinks "abstract things" are the thing that does not exist in 
temporal/physical space.  I have defined it as those that doesn't exist 
in the web because other abstract definition is irrelevant to the web in 
practice.

There is only something acts as an Information but not is Information.  
A book can be an Information to me.  But it will only be a toy to my 
2-year old son.  Everything can act as information resource.  A person 
can act as an information resource.  In the web, such as Pat, just makes 
its URI returns something useful.  He might as well not to do so by 
using a 303 on his URI.  To whose right do we fault someone's decision 
regarding this?
> You are "begging the question" - it all depends on what you mean by 
> 'false'.   I specifically said it in N3, using "FalseDocument".  That 
> is the class (for the sake of this argument) of documents which convey 
> a falsehood.
>
> If the document were in RDF, I could say it at a higher level:
>
>   [ is log:semantics of <http://www.ihmc.us/users/phayes/PatHayes> ] a 
> log:Falsehood.
>
> In other words, the graph you get when you acces Pat's document is a 
> logical falsehood.
> It would contain something like the triple
>
> <http://www.ihmc.us/users/phayes/PatHayes. a foaf:Person.
>
> when I know that
> <http://www.ihmc.us/users/phayes/PatHayes> a gen:InformationResource,
How would you get the last assertion? Assuming the document is cached in 
your laptop, then the same document becomes true?  Or, assuming Pat 
prints a hard copy of the same page and send it to you via snail mail.  
Do you have to make it an information resource or not by checking if it 
delivered by first-class mail or Fedex?

Here is what you, along with other authors, write in the section 1.2.1 
of URI spec http://www.ietf.org/rfc/rfc3986.txt
"A URI may be represented in a variety of ways; e.g., ink on paper, 
pixels on a screen, or a sequence of character encoding octets. The 
interpretation of a URI depends only on the characters used and not on 
how those characters are represented in a network protocol."

The real question is: is this so-called "Falsehood document" post a 
threat to the web?  My guesses any RDF engine would be just as happy to 
treat any RDF document in the same way regardless of how the document is 
finally fed into the engine.
>> I really want to understand on which ground they can be false.  We 
>> cannot say (1) is wrong, right? because Pat is the innocent party, 
>> who are dragged into this debate by me.  But how can (2) be wrong 
>> too?  As you said latter, a representation is a set of bit, and the 
>> identity is the content.  And the representation of that URI did talk 
>> about Pat, doesn't it?
>
> It says that a document is Pat.  That is wrong.
Where it says <http://www.ihmc.us/users/phayes/PatHayes> is a document?  
Pat insist it is a Person. Of course, in the open world, you can 
interpret as wrong but that doesn't make 
<http://www.ihmc.us/users/phayes/PatHayes> wrong, right? 
> I take this to mean:  people create things.
>
>> and there are creators for web pages.
>
> I take this to mean:  People create information resources (aka web 
> pages).
>
>>  No matter what, we need to create an additional URI.
>
> What for?  The thi
>
>>  303 tries to create a different URI to separate resource from page.
>
> It allows the URI for a person (say) and the URI for a page to be 
> different.  Yes. Even Pat is convinced of this now.
> You really can't build a serious knowledge representation system n 
> which you can't talk about a person and their web page separately as 
> first class objects.
Who said we cannot? For instance,

_:patsPage a web:Representation;
                web:repOf <http://www.ihmc.us/users/phayes/PatHayes>;
                     web:contentType "text/html".

Can we start talking _:patsPage now?

Xiaoshu

Received on Sunday, 25 November 2007 20:48:17 UTC