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Re: true/false in RDF?

From: Jeremy Wong <jeremy@miko.hk>
Date: Mon, 14 Mar 2005 14:10:53 +0800
Message-ID: <000201c5285c$e702a660$6702a8c0@michaelxp>
To: "Joshua Allen" <joshuaa@microsoft.com>, <semantic-web@w3.org>
In my opinion, the advantage of using typed literal is its predefined value-space which is better known. If you use an object value, you'll need to define its class extension, i.e. the value space. Other people need to learn your object value.

Since many content provider may use a boolean value, using an object value rather than a data value may induce performance problem. Consider if there are some resources having the same meaning as your true object, "http://xmlns.com/wordnet/1.6/true", then we shall have some owl:sameAs statements...

R1 owl:sameAs http://xmlns.com/wordnet/1.6/true

R2 owl:sameAs http://xmlns.com/wordnet/1.6/true

...
Rn owl:sameAs http://xmlns.com/wordnet/1.6/true


A simple implementation of owl:sameAs inference is to duplicate statements, i.e. if we have one statement..

http://foobar/page.html P1 http://xmlns.com/wordnet/1.6/true


Then n more statements will be generated...

http://foobar/page.html P1 R1
http://foobar/page.html P1 R2
...
http://foobar/page.html P1 Rn

It would consume very huge memory space and even computation power. The rate of expansion is about n^2.


Jeremy

----- Original Message ----- 
  寄件者: Joshua Allen 
  收件者: Jeremy Wong ; semantic-web@w3.org 
  傳送日期: Monday, 14 March, 2005 13:48
  主旨: RE: true/false in RDF?


  Yeah, that’s what I intended to express with my first example – if you use a literal, the literal is absolutely meaningless without type information.



  Why not just use URIs which mean “true” and “false” and do away with typing?  The only advantages I can see for typing are imaginary (compile time/run-time checks?!?!) and the disadvantage is real.




------------------------------------------------------------------------------

  From: Jeremy Wong [mailto:jeremy@miko.hk] 
  Sent: Sunday, March 13, 2005 9:35 PM
  To: Joshua Allen; semantic-web@w3.org
  Subject: Re: true/false in RDF?



  I am not too familar with N3 notation about datatype, therefore I provide my example in RDF/XML



  <rdf:Description rdf:about="http://foobar/page.html" xmlns:myterms="urn:myterms">

    <myterms:isCached rdf:datatype="http://www.w3.org/TR/XMLSchema#boolean">true</myterms:isCached>

  </rdf:Description>



  We have typed literal already. Why do you still consider object value?





  Jeremy

    ----- Original Message ----- 

    From: Joshua Allen 

    To: semantic-web@w3.org 

    Sent: Monday, March 14, 2005 12:16 PM

    Subject: true/false in RDF?



    I’ve decided that I want to use URI object values for my Boolean triples, rather than the literals “true/false”.  In other words, instead of:



    http://foobar/page.html  urn:myterms:isCached   “true”



    I want to use:



    http://foobar/page.html  urn:myterms:isCached   http://xmlns.com/wordnet/1.6/true




    I can find zero examples of the latter; only the former.  But I think the latter is right.  Why am I wrong?
Received on Monday, 14 March 2005 09:38:22 UTC

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