HPCT vs dynamics

CSGnet Archive CSG1993
1

[Martin Taylor 931013 18:20]
(Gavan Lintern Oct 1993 17:15:57)

This was originally written as a private note, to avoid cluttering the net
with too many of my fulminations, but after writing it I thought perhaps
it might be worth posting.

Since my first note, some responses have clarified the purpose of the CROWD
program. It is now evident to me that there is a sharp divergence here
between HPCT and ecological/dynamical systems. In the former view (if I read
those comments correctly) the behavior of concern is that of the individual
creatures. In the latter view, these examples suggest how organized patterns
might be assembled (without instruction) from independent elements. As a
further note here, this is a sharp and apparently irreconciliable difference.

I do not think there is any difference, except if someone argues that the
dynamic system approach is suited to explain the behaviour of individual
organisms. Then there might be a difference, or rather, a chasm.

I got several compliments, from Bill Powers, Rick Marken, and other
attendees at this year's Durango Control Systems Group meeting, for a
talk that treated the development of language as an approach to a complex
dynamical attractor. The individuals using language were taken to be
"classical" HPCT systems, but their interactions form a complex dynamical
system that must have attractors that are stable in many dimensions, if
not all.

Some posters to CSG-L talk about dynamics as "trendy science," as if
there were a dichotomy, but I think this always is applied to individual
psychology, not to interpersonal interactions.

Where there is an issue is when someone says that structures such as rings
and arcs in a crowd are controlled variables, and there is even more
squawking if someone claims that this control is somehow "social" as
opposed to in the individual crowd members. HPCT says each individual
in the crowd controls their own perceptions, which are probably not related
to crowd structures. The structures one sees are perceived by an outside
observer, and are consequences of the interactions among persons controlling
for quite other things. The crowd is a dynamic structure because of the
interactions among HPCT individuals. Modelling, such as the CROWD program,
shows that crowd structures CAN develop in the absence of any control for
their maintenance.

Martin

2

[From Oded Maler 930914]

* [Martin Taylor 931013 18:20]

···

*
* Some posters to CSG-L talk about dynamics as "trendy science," as if
* there were a dichotomy, but I think this always is applied to individual
* psychology, not to interpersonal interactions.
*
* Where there is an issue is when someone says that structures such as rings
* and arcs in a crowd are controlled variables, and there is even more
* squawking if someone claims that this control is somehow "social" as
* opposed to in the individual crowd members. HPCT says each individual
* in the crowd controls their own perceptions, which are probably not related
* to crowd structures. The structures one sees are perceived by an outside
* observer, and are consequences of the interactions among persons controlling
* for quite other things. The crowd is a dynamic structure because of the
* interactions among HPCT individuals. Modelling, such as the CROWD program,
* shows that crowd structures CAN develop in the absence of any control for
* their maintenance.
*
* Martin
*

A "ring" is an attractor for a CROWD program with cetain parameters.
It is an attractor for a "social" entity composed of individuals
who control for perception in another level (level of organization).

An individual personal control hierarchy with orthogonal goals,
might be an attractor in the space of all possible systems under
the dynamics of interaction-with-the-world + re-organization.

Living control systems might be an attractor among forms of life
under the dynamics of evolution.

It all depends on the level of analysis.

--Oded

--

Oded Maler, VERIMAG, Miniparc ZIRST, 38330 Montbonnot, France
Phone: 76909635 Fax: 76413620 e-mail: Oded.Maler@imag.fr

3

[Martin Taylor 931014 14:30]
(Oded Maler 930914)

An individual personal control hierarchy with orthogonal goals,
might be an attractor in the space of all possible systems under
the dynamics of interaction-with-the-world + re-organization.

Living control systems might be an attractor among forms of life
under the dynamics of evolution.

It all depends on the level of analysis.

I like that, but it doesn't capture what I think is a legitimate complaint
of the PCT theorist: it is inappropriate to think in terms of non-linear
dynamics when considering the actions of a control hierarchy, and
inappropriate to think of "social" control when considering the effects
that appear when independent control systems interact.

It is technically true that all "control" is also an aspect of the
non-linear dynamics of the system. But it is more effective to ignore
that and deal with the specifically control aspects using the conceptual
tools specialized for the purpose.

4

From Tom Bourbon [931014.1654]

[From Oded Maler 930914]

A "ring" is an attractor for a CROWD program with cetain parameters.
It is an attractor for a "social" entity composed of individuals
who control for perception in another level (level of organization).

An individual personal control hierarchy with orthogonal goals,
might be an attractor in the space of all possible systems under
the dynamics of interaction-with-the-world + re-organization.

Living control systems might be an attractor among forms of life
under the dynamics of evolution.

It all depends on the level of analysis.

Oded,
In all of these examples, the word "attractor" refers to a state or place
where things end up. There is nothing at all "attractive" or
"attracting" about the places, but sometimes people begin to talk as though
there were. Too bad the people who started that line of talk didn't refer
to the places where things end up as just that.

Later,

Tom

5

* >[From Oded Maler 930915]

* Tom Bourbon [931014.1654]

···

*
* Oded,
* In all of these examples, the word "attractor" refers to a state or place
* where things end up. There is nothing at all "attractive" or
* "attracting" about the places, but sometimes people begin to talk as though
* there were. Too bad the people who started that line of talk didn't refer
* to the places where things end up as just that.
*

It is the place where things end up, regardless of initial conditions
and many other details, just because of the intrinsic dynamical
properties of the system. I agree that the word can be abused according
to the cultural context. When mathematicians talk about it the
meaning is clear (i.e., "the places, etc."), maybe when people
who deal with humans, intentions, goals (i.e., psychologists)
some confusion between the technical meaning and the daily use
of the word "attract" arises. I'm not sure this is what happens
all the time (I'm sure that when Kugler speaks about it, he means
technically). As Martin noted, it may not be the best or the
simplest type of analysis/explanation in some cases, but this
is open. An important example I didn't mention was that the set
of states of the ECS+environment where perception matches
reference is an attractor of a properly working (or a completely
blind..) control system.

--Oded

--

Oded Maler, VERIMAG, Miniparc ZIRST, 38330 Montbonnot, France
Phone: 76909635 Fax: 76413620 e-mail: Oded.Maler@imag.fr