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Re: space,time in KR: context, initial, final

From: Richard H. McCullough <rhm@cdepot.net>
Date: Tue, 17 Dec 2002 12:04:30 -0800
Message-ID: <001301c2a607$8313a5c0$bd7ba8c0@rhm8200>
To: "Godfrey Rust" <godfreyrust@dds.netkonect.co.uk>, "Patrick J. Hayes" <phayes@ai.uwf.edu>
Cc: "RDF-Interest" <www-rdf-interest@w3.org>, "Richard S. Latimer" <latimer1@att.net>
You make some excellent points.

1. My concept of "person" does not depend on legal status (e.g. age).

2. My concept of "time independent" is related to causality.
I view attributes (e.g. sex) as "constant", unless/until changed by some action (e.g. sex change operation).
In other words, there is a "long time interval" where we can view the attribute as "time independent".
I think this is a good way to characterize reality,
even though "long time interval" depends on the judgment of the "observer".

In summary:
    an attribute is a space-time-independent characteristic of an entity
    an action is a space-time-dependent characteristic of an entity
    actions change attributes
============
Dick McCullough 
knowledge := man do identify od existent done
knowledge haspart proposition list

  ----- Original Message ----- 
  From: Godfrey Rust 
  To: Richard H. McCullough ; Patrick J. Hayes 
  Cc: RDF-Interest ; Richard S. Latimer 
  Sent: Tuesday, December 17, 2002 5:07 AM
  Subject: Re: space,time in KR: context, initial, final


  Belated comments.
    ----- Original Message ----- 
    From: Richard H. McCullough 

    a. Jane has sex=female 
    b. Jane isa person 
    c. John do walk with a limp done 
    d. John do walk to the store done 
    a and b are attribute and relation statements which are independent of space-time. 

    GR> a is not independent if Jane has a sex change. If your datastore was for a sex-change clinic it would be the most significant variable. In some jurisdictions sex changes are not recognized (I understand from this week's newspapers that in the UK it will be possible in future to change your birth certificate) so this statement is both space and time dependent.

    b is space-time dependent according to your definition of "person". If it is a legal definition then in many jurisdictions it will be true only after one of Jane's birthdays, and which one will vary from place to place.

    c is an action statement which is independent of space-time. 

    GR> c is not time independent. Presumably Jane wasn't born walking, so it is not true until at least the time at which she could walk. After that it depends on whether the limp was genetic or acquired. She will also only walk with a limp in appropriate environments (eg not under water or if she is an astronaut).

    d is an action statement which depends on space-time. 

    GR> ...as are all the rest. In any case they are bounded by Jane's life: and that may have begun at conception or at birth, or any time between or even before, according to your religious or philosophical conjecture, or the requirements of your datastore. 

    Any definition of space-time independence is itself space-time dependent, and dependent on the view of the domain within which, or the authority by which, it is expressed.  (But then again, that's just my point of view...:-)

    I dont disagree with your general approach to contexts, btw Richard: it is quite similar to the one we use, but beware of making non-contextual statements about them as they undermine its credibility and usefulness.

    Godfrey Rust
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Received on Tuesday, 17 December 2002 15:04:39 GMT

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