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

From: Richard H. McCullough <rhm@cdepot.net>
Date: Sat, 14 Dec 2002 05:51:16 -0800
Message-ID: <000e01c2a377\$e03e9a30\$bd7ba8c0@rhm8200>
To: "Patrick J. Hayes" <phayes@ai.uwf.edu>
Cc: "RDF-Interest" <www-rdf-interest@w3.org>, "Richard S. Latimer" <latimer1@att.net>
```1. general context
The basic KR proposition has the form
at context { statement }
Including space,time in context permits making statements which isolate & focus on space-time-independent properties.  Some statements are space-time-dependent.  The distinction is important because space-time-independent statements have wider implications.
Example statements:
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.
c is an action statement which is independent of space-time.
d is an action statement which depends on space-time.

2. action initial and final characteristics
The fundamental characteristics of all actions are:
a. they change the properties of existents;
b. they are performed by an entity.
KR specifies the changes by a set of initial characteristics which exist before the action, and a set of final characteristics which exist after the action.  Initial and final characteristics may include space-time.
Example statements:
c. water do change from temperature=positive to temperature=0 done causes water do change from phase=liquid to phase=solid done
d. John do walk from his house to the store done
c is a causality statement which is independent of space-time.
d is an action statement which depends on space-time.

3. action contexts
space,time specifies where,when an action occurs.  Typically, they specify the initial space,time of the action.  For some actions, they specify the final space,time.
Example propositions:
a. at 8 am { John do go to the store done }
b. at 5 pm { John do finish od work done }
a is a proposition with a context specifying the initiation of an action.
b is a proposition with a context specifying the completion of an action.
============
Dick McCullough
knowledge := man do identify od existent done
knowledge haspart proposition list
```
Received on Saturday, 14 December 2002 08:51:17 UTC

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