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A system is '''self-sustaining''' (or '''self-sufficient''') if it can maintain itself by independent effort. The system self-sustainability is: | |||
# the degree at which the system can sustain itself without external support | |||
# the fraction of time in which the system is self-sustaining | |||
Self-sustainability is considered one of the [[list of system quality attributes|"ilities"]] and is closely related to [[sustainability]] and [[availability]]. In the Economics literature, a system that has the quality of being self-sustaining is also referred to as an [[autarky]]. | |||
==Formal definition== | |||
'''1.''' Let <math>E</math> be a random variable that denotes the steady state number of external entities on which the system depends. Let <math>p(v) </math> be the probability that the system depends on <math>v</math> external entities, <math>p(v)=P(E=v)</math>. Then, the system self-sustainability, <math>S</math>, is <math>S=p(0)</math>. | |||
'''2.''' Let <math>e_t</math> be the expected time during which the system is self-sustaining from time 0 up to time <math>t</math>. Then, the system self-sustainability is the steady state fraction of time in which it is self-sustaining, <math>S=\lim_{t \rightarrow \infty} {e_t}/{t}</math> | |||
==Examples== | |||
===Political states=== | |||
[[Autarky]] exists whenever an entity can survive or continue its activities without external assistance. Autarky is not necessarily economic. For example, a military autarky would be a state that could defend itself without help from another country. | |||
===Labor=== | |||
According to the Department of Labor of the state of Idaho, an employed adult shall be considered self-sufficient if the family income exceeds 200% of the Office of Management and Budget poverty income level guidelines.<ref name="labor">IDAHO Department of Labor (1999). [http://labor.idaho.gov/wia1/policies/wiap7-99.pdf "Definition of Self-sufficiency."] Retrieved on 2010-06-26.</ref> | |||
===Peer-to-peer swarming=== | |||
In peer-to-peer swarming systems, a swarm is self-sustaining if all the blocks of its files are available among peers (excluding seeds and publishers).<ref name="p2p">Menasche, Rocha, de Souza e Silva, Leao, Towsley, Venkataramani (2010). [http://arxiv.org/abs/1004.0395 "Estimating self-sustainability in peer-to-peer swarming systems"] Retrieved on 2010-06-26.</ref> | |||
==Discussion== | |||
===Self-sustainability and survivability=== | |||
Whereas self-sustainability is a quality of one’s independence, [[survivability]] applies to the future maintainability of one’s self-sustainability and indeed one’s existence. Many believe that more self-sustainability guarantees a higher degree of survivability. But just as many oppose this, arguing that it is not self-sustainability that is essential for survivability, but on the contrary specialization and thus dependence.<ref name="survival">What and Who is Self-Sufficient? by Katrien Vander Straeten</ref> | |||
Consider the first two examples presented above. Among countries, commercial treats are as important as self-sustainability. An [[autarky]] is usually inefficient. Among people, social ties have been shown to be correlated to happiness and success as much as self-sustainability.<ref name="SocialNets">{{youtube|id=6a_KF7TYKVc|title=Social Networks in Plain English}}</ref> | |||
==Notes and references== | |||
{{reflist|colwidth=25em}} | |||
==See also== | |||
* [[Availability]] | |||
* [[List of system quality attributes]] | |||
* [[Self-sufficiency]] | |||
* [[Survivalism]] | |||
{{DEFAULTSORT:Self-Sustainability}} | |||
[[Category:Applied probability]] |
Revision as of 02:06, 11 January 2013
A system is self-sustaining (or self-sufficient) if it can maintain itself by independent effort. The system self-sustainability is:
- the degree at which the system can sustain itself without external support
- the fraction of time in which the system is self-sustaining
Self-sustainability is considered one of the "ilities" and is closely related to sustainability and availability. In the Economics literature, a system that has the quality of being self-sustaining is also referred to as an autarky.
Formal definition
1. Let be a random variable that denotes the steady state number of external entities on which the system depends. Let be the probability that the system depends on external entities, . Then, the system self-sustainability, , is .
2. Let be the expected time during which the system is self-sustaining from time 0 up to time . Then, the system self-sustainability is the steady state fraction of time in which it is self-sustaining,
Examples
Political states
Autarky exists whenever an entity can survive or continue its activities without external assistance. Autarky is not necessarily economic. For example, a military autarky would be a state that could defend itself without help from another country.
Labor
According to the Department of Labor of the state of Idaho, an employed adult shall be considered self-sufficient if the family income exceeds 200% of the Office of Management and Budget poverty income level guidelines.[1]
Peer-to-peer swarming
In peer-to-peer swarming systems, a swarm is self-sustaining if all the blocks of its files are available among peers (excluding seeds and publishers).[2]
Discussion
Self-sustainability and survivability
Whereas self-sustainability is a quality of one’s independence, survivability applies to the future maintainability of one’s self-sustainability and indeed one’s existence. Many believe that more self-sustainability guarantees a higher degree of survivability. But just as many oppose this, arguing that it is not self-sustainability that is essential for survivability, but on the contrary specialization and thus dependence.[3]
Consider the first two examples presented above. Among countries, commercial treats are as important as self-sustainability. An autarky is usually inefficient. Among people, social ties have been shown to be correlated to happiness and success as much as self-sustainability.[4]
Notes and references
43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.
See also
- ↑ IDAHO Department of Labor (1999). "Definition of Self-sufficiency." Retrieved on 2010-06-26.
- ↑ Menasche, Rocha, de Souza e Silva, Leao, Towsley, Venkataramani (2010). "Estimating self-sustainability in peer-to-peer swarming systems" Retrieved on 2010-06-26.
- ↑ What and Who is Self-Sufficient? by Katrien Vander Straeten
- ↑ Template:Youtube