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In computational complexity and optimization the no free lunch theorem is a result that states that for certain types of mathematical problems, the computational cost of finding a solution, averaged over all problems in the class, is the same for any solution method. The name alludes to the saying "no such thing as a free lunch", that is, no method offers a "short cut". This is under the assumption that the search space is a probability density function. It does not apply to the case where the search space has underlying structure (e.g., is a differentiable function) that can be exploited more efficiently (e.g., Newton's method in optimization) than random search or even has closed-form solutions (e.g., the extrema of a quadratic polynomial) that can be determined without search at all. For such probabilistic assumptions, the outputs of all procedures solving a particular type of problem are statistically identical. A colourful way of describing such a circumstance, introduced by David Wolpert and William G. Macready in connection with the problems of search and optimization, is to say that there is no free lunch. Wolpert had previously derived no free lunch theorems for machine learning (statistical inference). Before Wolpert's article was published, Cullen Schaffer independently proved a restricted version of one of Wolpert's theorems and used it to critique the current state of machine learning research on the problem of induction.

In the "no free lunch" metaphor, each "restaurant" (problem-solving procedure) has a "menu" associating each "lunch plate" (problem) with a "price" (the performance of the procedure in solving the problem). The menus of restaurants are identical except in one regard – the prices are shuffled from one restaurant to the next. For an omnivore who is as likely to order each plate as any other, the average cost of lunch does not depend on the choice of restaurant. But a vegan who goes to lunch regularly with a carnivore who seeks economy might pay a high average cost for lunch. To methodically reduce the average cost, one must use advance knowledge of a) what one will order and b) what the order will cost at various restaurants. That is, improvement of performance in problem-solving hinges on using prior information to match procedures to problems.

In formal terms, there is no free lunch when the probability distribution on problem instances is such that all problem solvers have identically distributed results. In the case of search, a problem instance in this context is a particular objective function, and a result is a sequence of values obtained in evaluation of candidate solutions in the domain of the function. For typical interpretations of results, search is an optimization process. There is no free lunch in search if and only if the distribution on objective functions is invariant under permutation of the space of candidate solutions. This condition does not hold precisely in practice, but an "(almost) no free lunch" theorem suggests that it holds approximately.

A Gödel machine is a hypothetical self-improving computer program that solves problems in an optimal way. It uses a recursive self-improvement protocol in which it rewrites its own code when it can prove the new code provides a better strategy. The machine was invented by Jürgen Schmidhuber (first proposed in 2003), but is named after Kurt Gödel who inspired the mathematical theories.

The Gödel machine is often discussed when dealing with issues of meta-learning, also known as "learning to learn." Applications include automating human design decisions and transfer of knowledge between multiple related tasks, and may lead to design of more robust and general learning architectures. Though theoretically possible, no full implementation has been created.

The Gödel machine is often compared with Marcus Hutter's AIXItl, another formal specification for an artificial general intelligence. Schmidhuber points out that the Gödel machine could start out by implementing AIXItl as its initial sub-program, and self-modify after it finds proof that another algorithm for its search code will be better.

The Löwenmensch figurine or Lion-man of the Hohlenstein-Stadel is a prehistoric ivory sculpture discovered in the Hohlenstein-Stadel, a German cave in 1939. The German name, Löwenmensch, meaning "lion-human", is used most frequently because it was discovered and is exhibited in Germany.

The lion-headed figurine is the oldest-known zoomorphic (animal-shaped) sculpture in the world, and the oldest-known uncontested example of figurative art. It has been determined by carbon dating of the layer in which it was found to be between 35,000 and 40,000 years old, and therefore is associated with the archaeological Aurignacian culture of the Upper Paleolithic. It was carved out of mammoth ivory using a flint stone knife. Seven parallel, transverse, carved gouges are on the left arm.

After several reconstructions that have incorporated newly found fragments, the figurine stands 31.1 cm (12.2 in) tall, 5.6 cm (2.2 in) wide, and 5.9 cm (2.3 in) thick. It currently is displayed in the Museum Ulm, Germany.

The Autumn of the Middle Ages, The Waning of the Middle Ages, or Autumntide of the Middle Ages (published in 1919 as Herfsttij der Middeleeuwen and translated into English in 1924, German in 1924, and French in 1932), is the best-known work by the Dutch historian Johan Huizinga.

In the book, Huizinga presents the idea that the exaggerated formality and romanticism of late medieval court society was a defense mechanism against the constantly increasing violence and brutality of general society. He saw the period as one of pessimism, cultural exhaustion, and nostalgia, rather than of rebirth and optimism.

His main conclusion is that the combination of required modernization of statehood governance, stuck in traditionalism, in combination with the exhausting inclusion of an ever-growing corpus of Catholic rites and popular beliefs in daily life, led to the implosion of late medieval society. This provided light to the rise of (religious) individualism, humanism and scientific progress: the renaissance.

The book was nominated for the 1939 Nobel Prize for Literature, but lost to the Finnish writer Frans Eemil Sillanpää.

Huizinga's work later came under some criticism, especially for relying too heavily on evidence from the rather exceptional case of the Burgundian court. Other criticisms include the writing of the book being "old-fashioned" and "too literary".

A new English translation of the book was published in 1996 because of perceived deficiencies in the original translation. The new translation, by Rodney Payton and Ulrich Mammitzsch, was based on the second edition of the Dutch publication in 1921 and compared with the German translation published in 1924.

To mark the centenary of Herfsttij, a new translation by Diane Webb appeared in 2020, published by Leiden University Press: Autumntide of the Middle Ages. According to Benjamin Kaplan, this translation "captures Huizinga's original voice better than either of the two previous English editions". This new English edition also includes for the first time 300 full-colour illustrations of all the works of art Huizinga mentions in his text.

In the 1970s, Radio Netherlands produced an audio series about the book, entitled "Autumn of the Middle Ages: A Six-part History in Words and Music from the Low Countries".

Slow-scan television (SSTV) is a picture transmission method, used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color.

A literal term for SSTV is narrowband television. Analog broadcast television requires at least 6 MHz wide channels, because it transmits 25 or 30 picture frames per second (see ITU analog broadcast standards), but SSTV usually only takes up to a maximum of 3 kHz of bandwidth. It is a much slower method of still picture transmission, usually taking from about eight seconds to a couple of minutes, depending on the mode used, to transmit one image frame.

Since SSTV systems operate on voice frequencies, amateurs use it on shortwave (also known as HF by amateur radio operators), VHF and UHF radio.

This Is the Boke of Cokery, or The Boke of Cokery, is believed to be the first cookery book printed in English. The name of the author is unknown. It was printed and published by Richard Pynson in 1500. The book remained in print for many years in the 16th century, but was superseded and forgotten by the 18th. The only known surviving copy of the book is in the possession of the Marquess of Bath at Longleat House, Wiltshire.

Mummia, mumia, or originally mummy referred to several different preparations in the history of medicine, from "mineral pitch" to "powdered human mummies". It originated from Arabic mūmiyā "a type of resinous bitumen found in Western Asia and used curatively" in traditional Islamic medicine, which was translated as pissasphaltus (from "pitch" and "asphalt") in ancient Greek medicine. In medieval European medicine, mūmiyā "bitumen" was transliterated into Latin as mumia meaning both "a bituminous medicine from Persia" and "mummy". Merchants in apothecaries dispensed expensive mummia bitumen, which was thought to be an effective cure-all for many ailments. It was also used as an aphrodisiac. Beginning around the 12th century when supplies of imported natural bitumen ran short, mummia was misinterpreted as "mummy", and the word's meaning expanded to "a black resinous exudate scraped out from embalmed Egyptian mummies". This began a period of lucrative trade between Egypt and Europe, and suppliers substituted rare mummia exudate with entire mummies, either embalmed or desiccated. After Egypt banned the shipment of mummia in the 16th century, unscrupulous European apothecaries began to sell fraudulent mummia prepared by embalming and desiccating fresh corpses. During the Renaissance, scholars proved that translating bituminous mummia as mummy was a mistake, and physicians stopped prescribing the ineffective drug. Lastly, artists in the 17–19th centuries used ground up mummies to tint a popular oil-paint called mummy brown.

In computer programming, a poltergeist (or gypsy wagon) is a short-lived, typically stateless object used to perform initialization or to invoke methods in another, more permanent class. It is considered an anti-pattern. The original definition is by Michael Akroyd 1996 - Object World West Conference:

"As a gypsy wagon or a poltergeist appears and disappears mysteriously, so does this short lived object. As a consequence the code is more difficult to maintain and there is unnecessary resource waste. The typical cause for this anti-pattern is poor object design."

A poltergeist can often be identified by its name; they are often called "manager_", "controller_", "supervisor", "start_process", etc.

Sometimes, poltergeist classes are created because the programmer anticipated the need for a more complex architecture. For example, a poltergeist arises if the same method acts as both the client and invoker in a command pattern, and the programmer anticipates separating the two phases. However, this more complex architecture may actually never materialize.

Poltergeists should not be confused with long-lived, state-bearing objects of a pattern such as model–view–controller, or tier-separating patterns such as business-delegate.

To remove a poltergeist, delete the class and insert its functionality in the invoked class, possibly by inheritance or as a mixin.

In computer science, program synthesis is the task to construct a program that provably satisfies a given high-level formal specification. In contrast to program verification, the program is to be constructed rather than given; however, both fields make use of formal proof techniques, and both comprise approaches of different degrees of automation. In contrast to automatic programming techniques, specifications in program synthesis are usually non-algorithmic statements in an appropriate logical calculus.

The primary application of program synthesis is to relieve the programmer of the burden of writing correct, efficient code that satisfies a specification. However, program synthesis also has applications to superoptimization and inference of loop invariants.

A zero-rupee note is a banknote imitation issued in India as a means of helping to fight systemic political corruption. The notes are "paid" in protest by angry citizens to government functionaries who solicit bribes in return for services which are supposed to be free. Zero rupee notes, which are made to resemble the regular 50 rupee banknote of India, are the creation of a non-governmental organization known as 5th Pillar which has, since their inception in 2007, distributed over 2.5 million notes as of August 2014. The notes remain in current use and thousands of notes are distributed every month.