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🔗 Computing

Lambda lifting is a meta-process that restructures a computer program so that functions are defined independently of each other in a global scope. An individual "lift" transforms a local function into a global function. It is a two step process, consisting of;

• Eliminating free variables in the function by adding parameters.
• Moving functions from a restricted scope to broader or global scope.

The term "lambda lifting" was first introduced by Thomas Johnsson around 1982 and was historically considered as a mechanism for implementing functional programming languages. It is used in conjunction with other techniques in some modern compilers.

Lambda lifting is not the same as closure conversion. It requires all call sites to be adjusted (adding extra arguments to calls) and does not introduce a closure for the lifted lambda expression. In contrast, closure conversion does not require call sites to be adjusted but does introduce a closure for the lambda expression mapping free variables to values.

The technique may be used on individual functions, in code refactoring, to make a function usable outside the scope in which it was written. Lambda lifts may also be repeated, in order to transform the program. Repeated lifts may be used to convert a program written in lambda calculus into a set of recursive functions, without lambdas. This demonstrates the equivalence of programs written in lambda calculus and programs written as functions. However it does not demonstrate the soundness of lambda calculus for deduction, as the eta reduction used in lambda lifting is the step that introduces cardinality problems into the lambda calculus, because it removes the value from the variable, without first checking that there is only one value that satisfies the conditions on the variable (see Curry's paradox).

Lambda lifting is expensive on processing time for the compiler. An efficient implementation of lambda lifting is ${\displaystyle O(n^{2})}$ on processing time for the compiler.

In the untyped lambda calculus, where the basic types are functions, lifting may change the result of beta reduction of a lambda expression. The resulting functions will have the same meaning, in a mathematical sense, but are not regarded as the same function in the untyped lambda calculus. See also intensional versus extensional equality.

The reverse operation to lambda lifting is lambda dropping.

Lambda dropping may make the compilation of programs quicker for the compiler, and may also increase the efficiency of the resulting program, by reducing the number of parameters, and reducing the size of stack frames. However it makes a function harder to re-use. A dropped function is tied to its context, and can only be used in a different context if it is first lifted.

🔗 Books 🔗 The KLF

The Manual (How to Have a Number One the Easy Way) is a 1988 book by "The Timelords" (Jimmy Cauty and Bill Drummond), better known as The KLF. It is a step-by-step guide to achieving a No.1 single with no money or musical skills, and a case study of the duo's UK novelty pop No. 1 "Doctorin' the Tardis".

🔗 Greece 🔗 Politics 🔗 Elections and Referendums

In governance, sortition (also known as selection by lot, allotment, demarchy, or Stochocracy) is the selection of political officials as a random sample from a larger pool of candidates. Filling individual posts or, more usually in its modern applications, to fill collegiate chambers. The system intends to ensure that all competent and interested parties have an equal chance of holding public office. It also minimizes factionalism, since there would be no point making promises to win over key constituencies if one was to be chosen by lot, while elections, by contrast, foster it. In ancient Athenian democracy, sortition was the traditional and primary method for appointing political officials, and its use was regarded as a principal characteristic of democracy.

Today, sortition is commonly used to select prospective jurors in common law-based legal systems and is sometimes used in forming citizen groups with political advisory power (citizens' juries or citizens' assemblies).

🔗 United States 🔗 Biography 🔗 Physics 🔗 Biography/science and academia 🔗 Physics/Biographies 🔗 United States/Washington - Seattle 🔗 Buddhism 🔗 Invention

Chester Floyd Carlson (February 8, 1906 – September 19, 1968) was an American physicist, inventor, and patent attorney born in Seattle, Washington.

He is best known for inventing electrophotography, the process performed today by millions of photocopiers worldwide. Carlson's process produced a dry copy, as contrasted with the wet copies then produced by the mimeograph process. Carlson's process was renamed xerography, a term that means "dry writing."

🔗 Video games 🔗 Horror

Doom is a first-person shooter game developed and published by id Software. Released on December 10, 1993, for DOS, it is the first installment in the Doom franchise. The player assumes the role of a space marine, later unofficially referred to as Doomguy, fighting through hordes of undead humans and invading demons. The game begins on the moons of Mars and finishes in hell, with the player traversing each level to find its exit or defeat its final boss. It is an early example of 3D graphics in video games, and has enemies and objects as 2D images, a technique sometimes referred to as 2.5D graphics.

Doom was the third major independent release by id Software, after Commander Keen (1990–1991) and Wolfenstein 3D (1992). In May 1992, id started developing a darker game focused on fighting demons with technology, using a new 3D game engine from the lead programmer, John Carmack. The designer Tom Hall initially wrote a science fiction plot, but he and most of the story were removed from the project, with the final game featuring an action-heavy design by John Romero and Sandy Petersen. Id published Doom as a set of three episodes under the shareware model, marketing the full game by releasing the first episode free. A retail version with an additional episode was published in 1995 by GT Interactive as The Ultimate Doom.

Doom was a critical and commercial success, earning a reputation as one of the best and most influential video games of all time. It sold an estimated 3.5 million copies by 1999, and up to 20 million people are estimated to have played it within two years of launch. It has been termed the "father" of first-person shooters and is regarded as one of the most important games in the genre. It has been cited by video game historians as shifting the direction and public perception of the medium as a whole, as well as sparking the rise of online games and communities. It led to an array of imitators and clones, as well as a robust modding scene and the birth of speedrunning as a community. Its high level of graphic violence led to controversy from a range of groups. Doom has been ported to a variety of platforms both officially and unofficially and has been followed by several games in the series, including Doom II (1994), Doom 3 (2004), Doom (2016), and Doom Eternal (2020), as well as the films Doom (2005) and Doom: Annihilation (2019).

🔗 United States 🔗 Companies 🔗 Retailing 🔗 Home Living 🔗 United States/Nebraska - Omaha

Nebraska Furniture Mart is the largest home furnishing store in North America selling furniture, flooring, appliances and electronics. NFM was founded in 1937 by Belarus-born Rose Blumkin, universally known as Mrs. B., in Omaha, Nebraska, United States. Under the motto "sell cheap and tell the truth," she worked in the business until age 103. In 1983, Mrs. B. sold a majority interest to Berkshire Hathaway in a handshake deal with Warren Buffett.

🔗 Technology 🔗 Television

A Nipkow disk (sometimes Anglicized as Nipkov disk; patented in 1884), also known as scanning disk, is a mechanical, rotating, geometrically operating image scanning device, patented in 1885 by Paul Gottlieb Nipkow. This scanning disk was a fundamental component in mechanical television through the 1920s and 1930s.

🔗 Biography 🔗 France

Pierre Picaud (French: [piko]) was a 19th-century shoemaker in Nîmes, France who may have been the basis for the character of Edmond Dantès in Alexandre Dumas, père's 1844 novel The Count of Monte Cristo.

In 1807, Picaud was engaged to marry a rich woman, but three jealous friends — Loupian, Solari, and Chaubart — falsely accused him of being a spy for England (a fourth friend, Allut, knew of their conspiracy, but did not report it). He was imprisoned in the Fenestrelle fortress for seven years, not even learning why until his second year there. During his imprisonment he ground a small passageway into a neighboring cell and befriended a wealthy Italian priest named Father Torri who was also held in the fortress. A year later, a dying Torri bequeathed to Picaud a treasure he had hidden in Milan. When Picaud was released after the fall of the French Imperial government in 1814, he took possession of the treasure, returned under another name to Paris and spent 10 years plotting revenge against his former friends.

Picaud first murdered Chaubart or had him murdered. Picaud's former fiancée had, two years after his disappearance, married his former friend Loupian, who became the subject of his most brutal revenge. Picaud tricked Loupian's daughter into marrying a criminal, whom he then had arrested. Loupian's daughter promptly died of shock. Picaud then burned down Loupian's restaurant, or arranged to have it burned down, leaving Loupian impoverished. Next, he fatally poisoned Solari and either manipulated Loupian's son into stealing some gold jewelry or framed him for committing the crime. The boy was sent to jail, and Picaud stabbed Loupian to death. He was himself then abducted by a vengeful Allut, who seriously injured Picaud while holding him captive. Picaud was eventually found by the French police, who recorded his confession before dying of his injuries. . Allut's deathbed confession forms the bulk of the French police records of the case. The detailed description of Picaud's experiences in prison, which could not have been known to Allut, were supposedly dictated to him by the ghost of Father Torri.

🔗 United States 🔗 Companies 🔗 Video games 🔗 United States/Washington - Seattle 🔗 United States/Washington

Valve Corporation, also known as Valve Software, is an American video game developer, publisher, and digital distribution company headquartered in Bellevue, Washington. It is the developer of the software distribution platform Steam and the Half-Life, Counter-Strike, Portal, Day of Defeat, Team Fortress, Left 4 Dead, and Dota series.

Valve was founded in 1996 by former Microsoft employees Gabe Newell and Mike Harrington. Their debut product, the PC first-person shooter Half-Life, was released in 1998 to critical acclaim and commercial success, after which Harrington left the company. In 2003, Valve launched Steam, which accounted for around half of digital PC game sales by 2011. By 2012, Valve employed around 250 people and was reportedly worth over US$3 billion, making it the most profitable company per employee in the United States. In the 2010s, Valve began developing hardware, such as the Steam Machine, a brand of gaming PCs, as well as the HTC Vive and Valve Index virtual reality headsets.

🔗 Computing 🔗 Computing/Early computers

The IBM 7950, also known as Harvest, was a one-of-a-kind adjunct to the Stretch computer which was installed at the United States National Security Agency (NSA). Built by IBM, it was delivered in 1962 and operated until 1976, when it was decommissioned. Harvest was designed to be used for cryptanalysis.