-- Messages from file: [SUMEX-AIM]<LENAT>MESSAGE.TXT;1
		 -- Monday, April 7, 1980 11:08:19 --

Mail from SU-SCORE rcvd at 7-Apr-80 1011-PST
Date:  7 Apr 1980 1007-PST
From: CSD.FAGAN at SU-SCORE
Subject: project 2 -- VM writeup
To: lenat at SU-SCORE

Doug,
 The following is the writeup on the status of the time-oriented representation
package.


Time-Oriented Knowledge Representation Package

One direction for the workbench section of this project is the
development of tools for representing knowledge about time-varying
situations.  This work has concentrating on the process of turning one
application program into a more general representation package.  The
application program (called VM) was designed for real-time
interpretation of measurement data from patients in the intensive care
unit using a rule-based approach.  This program was designed
specifically around the problem of aggregating many separate
determinations of patient measurements taken a period of time into a
historical record of changes in the patient's status.

The first step in the development of a useful package from an existing
program is the identification of the particular simplifying assumptions
of the application area. VM took advantage of the fact that the
ambiguity of the domain was primarily due to changes in therapeutic
context, rather than from poor signal sources, or a very imprecise
theory of how to interpret the signal data.  The representation of these
therapeutic contexts is limited by the assumption that only one of these
contexts can be used to describe the current setting.  The current design
for the time-oriented package allows for a more flexible representation
that will allow for more ambiguity (from all sources) but maintain a
simple control structure (forward-driven processing) for manipulating the
representation. This is accomplished by attaching measures of
belief/certainty to aggregates of conclusions
that have been derived over a period of time. A second step for
generalizing the system is the generation of
multiple expectations  for the appropriate ranges for incoming data
based on  uncertainty in the determination of the current context. 
These changes  will provide for a larger number of potential
applications of the time-base representation system.
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