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🔗 Computer science 🔗 Economics 🔗 Engineering 🔗 Gender Studies

Pareto efficiency or Pareto optimality is a situation where no action or allocation is available that makes one individual better off without making another worse off. The concept is named after Vilfredo Pareto (1848–1923), Italian civil engineer and economist, who used the concept in his studies of economic efficiency and income distribution. The following three concepts are closely related:

• Given an initial situation, a Pareto improvement is a new situation where some agents will gain, and no agents will lose.
• A situation is called Pareto-dominated or Pareto-inefficient if there is some possible Pareto improvement that has not been made.
• A situation is called Pareto-optimal or Pareto-efficient if no change could lead to improved satisfaction for some agent without some other agent losing or, equivalently, if there is no scope for further Pareto improvement (in other words, the situation is not Pareto-dominated).

The Pareto front (also called Pareto frontier or Pareto set) is the set of all Pareto-efficient situations.

Pareto originally used the word "optimal" for the concept, but as it describes a situation where a limited number of people will be made better off under finite resources, and it does not take equality or social well-being into account, it is in effect a definition of and better captured by "efficiency".

In addition to the context of efficiency in allocation, the concept of Pareto efficiency also arises in the context of efficiency in production vs. x-inefficiency: a set of outputs of goods is Pareto-efficient if there is no feasible re-allocation of productive inputs such that output of one product increases while the outputs of all other goods either increase or remain the same.

Pareto efficiency is measured along the production possibility frontier (PPF), which is a graphical representation of all the possible options of output for two products that can be produced using all factors of production.

Besides economics, the notion of Pareto efficiency has been applied to the selection of alternatives in engineering and biology. Each option is first assessed, under multiple criteria, and then a subset of options is ostensibly identified with the property that no other option can categorically outperform the specified option. It is a statement of impossibility of improving one variable without harming other variables in the subject of multi-objective optimization (also termed Pareto optimization).

🔗 Technology 🔗 Business 🔗 Marketing & Advertising

The theory of constraints (TOC) is a management paradigm that views any manageable system as being limited in achieving more of its goals by a very small number of constraints. There is always at least one constraint, and TOC uses a focusing process to identify the constraint and restructure the rest of the organization around it. TOC adopts the common idiom "a chain is no stronger than its weakest link". That means that organizations and processes are vulnerable because the weakest person or part can always damage or break them, or at least adversely affect the outcome.

🔗 Sanitation

A shit flow diagram (also called excreta flow diagram or SFD) is a high level technical drawing used to display how excreta moves through a location, and functions as a tool to identify where improvements are needed. The diagram has a particular focus on treatment of the waste, and its final disposal or use. SFDs are most often used in developing countries.

🔗 Computing 🔗 Telecommunications 🔗 Computer Security 🔗 Computer Security/Computing

Phreaking is a slang term coined to describe the activity of a culture of people who study, experiment with, or explore telecommunication systems, such as equipment and systems connected to public telephone networks. The term phreak is a sensational spelling of the word freak with the ph- from phone, and may also refer to the use of various audio frequencies to manipulate a phone system. Phreak, phreaker, or phone phreak are names used for and by individuals who participate in phreaking.

The term first referred to groups who had reverse engineered the system of tones used to route long-distance calls. By re-creating these tones, phreaks could switch calls from the phone handset, allowing free calls to be made around the world. To ease the creation of these tones, electronic tone generators known as blue boxes became a staple of the phreaker community. This community included future Apple Inc. cofounders Steve Jobs and Steve Wozniak.

The blue box era came to an end with the ever-increasing use of computerized phone systems which allowed telecommunication companies to discontinue the use of in-band signaling for call routing purposes. Instead, dialing information was sent on a separate channel which was inaccessible to the telecom customer. By the 1980s, most of the public switched telephone network (PSTN) in the US and Western Europe had adopted the SS7 system which uses out-of-band signaling for call control (and which is still in use to this day). Phreaking has since become closely linked with computer hacking.

🔗 Fictional characters 🔗 Chemistry 🔗 Measurement

Claude Émile Jean-Baptiste Litre is a fictional character created in 1978 by Kenneth Woolner of the University of Waterloo to justify the use of a capital L to denote litres.

The International System of Units usually only permits the use of a capital letter when a unit is named after a person. The lower-case character l might be difficult to distinguish from the upper-case character I or the digit 1 in certain fonts and styles, and therefore both the lower-case (l) and the upper-case (L) are allowed as the symbol for litre. The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L, a practice that is also widely followed in Canada and Australia.

Woolner perpetrated the April Fools' Day hoax in the April 1978 issue of "CHEM 13 News", a newsletter concerned with chemistry for school teachers. According to the hoax, Claude Litre was born on 12 February 1716, the son of a manufacturer of wine bottles. During Litre's extremely distinguished fictional scientific career, he purportedly proposed a unit of volume measurement that was incorporated into the International System of Units after his death in 1778.

The hoax was mistakenly printed as fact in the IUPAC journal Chemistry International and subsequently retracted.

🔗 Military history 🔗 Norway 🔗 Birds 🔗 Zoo 🔗 Military history/Nordic military history 🔗 Military history/European military history 🔗 Edinburgh

Major General Sir Nils Olav III, Baron of the Bouvet Islands (Norwegian: [ˌnɪls ˈôːlɑv]) is a king penguin who resides in Edinburgh Zoo, Scotland. He is the mascot and colonel-in-chief of the Norwegian King's Guard. The name 'Nils Olav' and associated ranks have been passed down through three king penguins since 1972, the current holder being Nils Olav III.

🔗 Germany 🔗 Robotics 🔗 Brands 🔗 Toys

Fischertechnik is a brand of construction toy. It was invented by Artur Fischer and is produced by fischertechnik GmbH in Waldachtal, Germany. Fans often refer to Fischertechnik as "FT" or "ft". It is used in education for teaching about simple machines, as well as motorization and mechanisms. The company also offers computer interface technology, which can be used to teach the theory of automation and robotics.

🔗 Biography 🔗 Biography/science and academia 🔗 Trains 🔗 Trains/UK Railways 🔗 Mills 🔗 Trains/Transport in Scotland 🔗 North East England

George Stephenson (9 June 1781 – 12 August 1848) was an English civil engineer and mechanical engineer during the Industrial Revolution. Renowned as the "Father of Railways", Stephenson was considered by the Victorians as a great example of diligent application and thirst for improvement. His chosen rail gauge, sometimes called "Stephenson gauge", was the basis for the 4-foot-8+1⁄2-inch (1.435 m) standard gauge used by most of the world's railways.

Pioneered by Stephenson, rail transport was one of the most important technological inventions of the 19th century and a key component of the Industrial Revolution. Built by George and his son Robert's company Robert Stephenson and Company, the Locomotion No. 1 was the first steam locomotive to carry passengers on a public rail line, the Stockton and Darlington Railway in 1825. George also built the first public inter-city railway line in the world to use locomotives, the Liverpool and Manchester Railway, which opened in 1830.

🔗 Skepticism 🔗 Paranormal

Jimmy Carter, United States president from 1977 until 1981, reported seeing an unidentified flying object while at Leary, Georgia, in 1969. While serving as governor of Georgia, Carter was asked (on September 14, 1973) by the International UFO Bureau in Oklahoma City to file a report of the sighting, and he filed a statement on September 18, mailed September 20. Since its writing, the report has been discussed several times by both ufologists and by members of the mainstream media.

🔗 Internet 🔗 Computing

.test is a reserved top-level domain intended for usage in software testing. It is guaranteed to never be registered into the Internet.

Along with .test, there are 11 other reserved test domains: .测试, .परीक्षा, .испытание, .테스트, .טעסט, .測試, .آزمایشی, .பரிட்சை, .δοκιμή, .إختبار, and .テスト.