Function vs Behavior

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Date: Fri, 22 Jun 90 17:28 PDT
From: bwilliam@parc.xerox.com
Subject: Function vs Behavior
To: shared-kr@sumex-aim.stanford.edu
Cc: bwilliam@parc.xerox.com
Message-id: <19900623002842.0.WILLIAMS@SHERMAN.parc.xerox.com>

Read on only if your interested in Function vs Structure

During last meeting's discussion of function and behavior, one proposal
was that they are not that dissimilar concepts, and that both are
describable within roughly the same language.   Coincidentally, that
morning I completed the final version of a paper for the automatic
generation of abstractions/approxiamtions workshop that elaborates on
essentially that position.  This might be of interest to the working
group as a simple but concrete example.  If anyone is interested in the
paper I would be glad to give them a copy.

Here is a brief description of the approach presented, within the
context of extracting function from behavior:

The task described in the paper is to automatically generate a
teleological account of how a device achieves a behavior of interest
(intended, faulty or whatever).  The class of devices studied are those
commonly explored in the qualitative reasoning community --- continuous
devices whose behavior is described qualitatively (specifically in terms
of regions of the device's state space).  Specifically, the behavior and
function of components are both described as equations in a
qualitative/quantitative algebra called Q1.

The perspective of the paper is that the function of a device's
component is described exactly by those features of the component's
behavior that contribute to the overall device's behavior of interest.
Additionally a device "works" by establishing a network of local
interactions (described by Q1 equations) that are produced by the
components and connections.  The problem then is, given a qualitative
description of a behavior of interest (e.g., intended behavior) and a
quantitative description of the component behaviors, construct the most
abstract description of the component interactions that allow the
behavior of interest to be derived.  The approach is demonstrated on a
very simple fluid regulation device.  (Note that this can also be viewed
as modelling approach, where the task is to construct the most abstract
model of a device that is sufficient to answer a set of questions of
interest.)

The following is the paper title and abstract.

		       Capturing How Things Work:  
       Constructing Critical Abstractions of Local Interactions.

	Central to most scientific and engineering tasks, such as
	design, diagnosis, analogy and design capture, is a
	representation of a device that captures its salient features
	with respect to how it works.  We take the perspective that a
	device works by constructing a topology of interactions between
	quantities.  To construct a parsimonious description of
	an interaction topology we introduce the concept of a critical
	abstraction --- a most abstract description of a topology
	relative to a set of queries, that preserves the link beween the
	individual mechanisms of a device, and the behaviors mentioned
	in the queries.  We present a constructive modelling technique
	for computing critical topologies using only the mathematical
	properties of the interaction topology representation.  This
	approach provides a foundation for more sophisticated
	teleological reasoning techniques.