Feedback - Revision history

Jfromm: /* Positive and Negative Feedback */

2011-03-03T22:05:33Z

Positive and Negative Feedback

← Older revision		Revision as of 17:05, 3 March 2011
Line 68:		Line 68:
	They leads to instable systems or polarization in general,		They leads to instable systems or polarization in general,
	rapid amplification of differences, and allows systems to		rapid amplification of differences, and allows systems to
	convert graded, uncertain inputs into decisive,		convert graded, uncertain inputs into decisive,
	all-or-none outputs, see also the entries for		all-or-none outputs, see also the entries for
	[[Butterfly Effect]],		[[Butterfly Effect]],

Jfromm: /* Positive and Negative Feedback */

2011-03-03T22:05:12Z

Positive and Negative Feedback

← Older revision		Revision as of 17:05, 3 March 2011
Line 54:		Line 54:
	=== Positive and Negative Feedback ===		=== Positive and Negative Feedback ===

	'''Negative feedback''' means a higher output		'''Negative feedback''' means a higher output reduces further input.
	reduces further input. It results in robust and stable systems,		Negative feedback loops are balancing, regulating and stabilizing.
			They oppose any direction of change which is imposed on the
			system. Negative feedback results in robust and stable systems,
	leveling of differences and equalization or stabilization in general,		leveling of differences and equalization or stabilization in general,
	and can be used to regain equilibrium. In mathematics this		and can be used to regain equilibrium. In mathematics this kind of
	kind of behavior towards a limt or fixed equilibrium state		behavior towards a limt or fixed equilibrium state is named convergence.
	is named convergence.

	'''Positive feedback''' means a higher output		'''Positive feedback''' means a higher output
	of the system increases further input. It leads to instable systems		of the system increases further input.
	or polarization in general, rapid amplification of differences,		Positive feedback loops are amplifying, reinforcing, and
	and allows systems to convert graded, uncertain inputs into decisive,		enhancing. They reinforace a direction of change.
			They leads to instable systems or polarization in general,
			rapid amplification of differences, and allows systems to
			convert graded, uncertain inputs into decisive,
	all-or-none outputs, see also the entries for		all-or-none outputs, see also the entries for
	[[Butterfly Effect]],		[[Butterfly Effect]],

Jfromm at 13:41, 26 February 2011

2011-02-26T13:41:17Z

← Older revision		Revision as of 08:41, 26 February 2011
Line 2:		Line 2:
	characterizes a process in which part of the output of a system is		characterizes a process in which part of the output of a system is
	returned (fed back) to its input in order to regulate its further		returned (fed back) to its input in order to regulate its further
	output. If the output becomes part of the input or changes the further		output. It describes a recursive process.
			If the output becomes part of the input or changes the further
	ouput, and the flow of information is closed, a feedback loop has been		ouput, and the flow of information is closed, a feedback loop has been
	established. In a feedback loop the output of a system is sent continuously		established. In a feedback loop the output of a system is sent continuously

Jfromm: /* Iteration */

2011-02-26T13:39:40Z

Iteration

← Older revision		Revision as of 08:39, 26 February 2011
Line 73:		Line 73:
	=== Iteration ===		=== Iteration ===

	[[Iteration]] is the mathematical counterpart of feedback.		[[Iteration]] is the mathematical counterpart of feedback and recursion.
	Examples are a [[Cellular_Automata\|CA]] or a		Examples are a [[Cellular_Automata\|CA]] or a
	[[Random_Boolean_Network\|RBN]].		[[Random_Boolean_Network\|RBN]].

Jfromm: /* Types and Forms */

2011-02-26T12:57:33Z

Types and Forms

← Older revision		Revision as of 07:57, 26 February 2011
Line 70:		Line 70:
	In mathematics this kind of behavior related		In mathematics this kind of behavior related
	to unrestricted growth is named divergence.		to unrestricted growth is named divergence.

			=== Iteration ===

			[[Iteration]] is the mathematical counterpart of feedback.
			Examples are a [[Cellular_Automata\|CA]] or a
			[[Random_Boolean_Network\|RBN]].

	== Relations ==		== Relations ==

Jfromm: New page: '''Feedback''' is an important term from cybernetics and control theory which characterizes a process in which part of the output of a system is returned (fed back) to its input in order...

2008-08-30T10:52:39Z

New page: '''Feedback''' is an important term from cybernetics and control theory which characterizes a process in which part of the output of a system is returned (fed back) to its input in order...

New page

'''Feedback''' is an important term from cybernetics and control theory which
characterizes a process in which part of the output of a system is
returned (fed back) to its input in order to regulate its further
output. If the output becomes part of the input or changes the further
ouput, and the flow of information is closed, a feedback loop has been
established. In a feedback loop the output of a system is sent continuously
back to regulate the input or output. Causal loops and circular processes
are typical for systems with feedbacks. If this feedback is used to control a
system (as for example in the [[Observer-Controller Pattern]] emphasized
by [[Organic Computing]]), the feedback signal indicates at the same time
the current state of the controlled element.

== Definition ==

{{SelfOrg}}

Feedback is a circular process in which part of the output of a system
is returned to its input in order to regulate its further output.
According to the [http://www.necsi.org:16080/community/wiki/index.php/Feedback NECSI Wiki],
"Feedback is a circular process of influence where action has effect on the actor".

== History ==

The idea of feedback loops originated in the field of cybernetics, control
theory and electrical engineering around 1950 and 1960.

W.R. Ashby noticed the importance of feedback in coupled
systems for forms of [[Self-Organization|self-organization]], which are more than
transitions from ‘parts separated’ to ‘parts joined’ (Ashby 1962).
He argued that no machine could by itself change its own organization,
if the behavior of each part is independent of the other parts' states.
He added further that a ‘self-organizing’ machine is only possible
by a machine coupled to another machine.

== Types and Forms ==

=== Cognitive Feedback Loops ===

The concept of an autonomic manager used in
[[Organic Computing]] and [[Autonomic Computing]]
in order to achieve [[Self-Star Properties|self-* properties]]
is usually based on a feedback loop. This cognitive feedback
loop consists of a perception phase, where the state of the
managed element is observed, monitored and analyzed, and
and a corresponding action phase, where the managed element
is controlled through corrective action which is planned and
executed.

* [[Perceive-Reason-Act Cycle|perceive-reason-act cycle]] in autonomous [[Agent|agents]]
* OC ([[Observer-Controller Pattern]]) loop in [[Organic Computing]]
* MAPE (Monitor-Analyze-Plan-Execute) loop in [[Autonomic Computing]]

=== Positive and Negative Feedback ===

'''Negative feedback''' means a higher output
reduces further input. It results in robust and stable systems,
leveling of differences and equalization or stabilization in general,
and can be used to regain equilibrium. In mathematics this
kind of behavior towards a limt or fixed equilibrium state
is named convergence.

'''Positive feedback''' means a higher output
of the system increases further input. It leads to instable systems
or polarization in general, rapid amplification of differences,
and allows systems to convert graded, uncertain inputs into decisive,
all-or-none outputs, see also the entries for
[[Butterfly Effect]],
[[Path Dependence]] and
[[Frozen Accident]]s.
In mathematics this kind of behavior related
to unrestricted growth is named divergence.

== Relations ==

Feedback is also related to recursion, self-invocation,
recurrence, iteration iterated maps and functions,
Iterative Function Systems (IFS) and self-similarity.
Recursion and self-invocation mean a function is
defined in terms of itself, which causes a function
to invoke or call itself during runtime.

== Links and References ==

W.R. Ashby, Principles of the self-organizing system, in “Principles of Self-Organization: Transactions of the University of Illinois Symposium”, H. Von Foerster and G. W. Zopf, Jr. (eds.), Pergamon Press (1962) pp. 255-278.

* [http://pespmc1.vub.ac.be/FEEDBACK.html PCP Entry for Feedback]

* [http://en.wikipedia.org/wiki/Feedback Main Wikipedia Entry for Feedback]

* [http://www.necsi.org:16080/community/wiki/index.php/Feedback NECSI Entry for Feedback]

[[Category:Basic Principles]]