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In computer science and mathematics, a full employment theorem is a term used, often humorously, to refer to a theorem which states that no algorithm can optimally perform a particular task done by some class of professionals. The name arises because such a theorem ensures that there is endless scope to keep discovering new techniques to improve the way at least some specific task is done.

For example, the full employment theorem for compiler writers states that there is no such thing as a provably perfect size-optimizing compiler, as such a proof for the compiler would have to detect non-terminating computations and reduce them to a one-instruction infinite loop. Thus, the existence of a provably perfect size-optimizing compiler would imply a solution to the halting problem, which cannot exist. This also implies that there may always be a better compiler since the proof that one has the best compiler cannot exist. Therefore, compiler writers will always be able to speculate that they have something to improve. A similar example in practical computer science is the idea of no free lunch in search and optimization, which states that no efficient general-purpose solver can exist, and hence there will always be some particular problem whose best known solution might be improved.

Similarly, Gödel's incompleteness theorems have been called full employment theorems for mathematicians. In theoretical computer science this field of study is known as Kolmogorov complexity, or the smallest program which outputs a given string.

Tasks such as virus writing and detection, and spam filtering and filter-breaking are also subject to Rice's theorem.

🔗 Video games 🔗 Computing

Habitat is a massively multiplayer online role-playing game (MMORPG) developed by LucasArts. It is the first attempt at a large-scale commercial virtual community that was graphic based. Initially created in 1985 by Randy Farmer and Chip Morningstar, the game was made available as a beta test in 1986 by Quantum Link, an online service for the Commodore 64 computer and the corporate progenitor to AOL. Both Farmer and Morningstar were given a First Penguin Award at the 2001 Game Developers Choice Awards for their innovative work on Habitat. As a graphical MUD it is considered a forerunner of modern MMORPGs unlike other online communities of the time (i.e. MUDs and massively multiplayer onlines with text-based interfaces). Habitat had a GUI and large user base of consumer-oriented users, and those elements in particular have made Habitat a much-cited project and acknowledged benchmark for the design of today's online communities that incorporate accelerated 3D computer graphics and immersive elements into their environments.

🔗 History 🔗 Visual arts

The Hockney–Falco thesis is a theory of art history, advanced by artist David Hockney and physicist Charles M. Falco. Both claimed that advances in realism and accuracy in the history of Western art since the Renaissance were primarily the result of optical instruments such as the camera obscura, camera lucida, and curved mirrors, rather than solely due to the development of artistic technique and skill. Nineteenth-century artists' use of photography had been well documented. In a 2001 book, Secret Knowledge: Rediscovering the Lost Techniques of the Old Masters, Hockney analyzed the work of the Old Masters and argued that the level of accuracy represented in their work is impossible to create by "eyeballing it". Since then, Hockney and Falco have produced a number of publications on positive evidence of the use of optical aids, and the historical plausibility of such methods. The hypothesis led to a variety of conferences and heated discussions.

🔗 Biology 🔗 Women's History 🔗 Anthropology 🔗 Human Genetic History 🔗 Molecular Biology 🔗 Molecular Biology/Molecular and Cell Biology 🔗 Molecular Biology/Genetics

In human genetics, the Mitochondrial Eve (more technically known as the Mitochondrial-Most Recent Common Ancestor, shortened to mt-Eve or mt-MRCA) is the matrilineal most recent common ancestor (MRCA) of all living humans. In other words, she is defined as the most recent woman from whom all living humans descend in an unbroken line purely through their mothers and through the mothers of those mothers, back until all lines converge on one woman.

In terms of mitochondrial haplogroups, the mt-MRCA is situated at the divergence of macro-haplogroup L into L0 and L1–6. As of 2013, estimates on the age of this split ranged at around 155,000 years ago, consistent with a date later than the speciation of Homo sapiens but earlier than the recent out-of-Africa dispersal.

The male analog to the "Mitochondrial Eve" is the "Y-chromosomal Adam" (or Y-MRCA), the individual from whom all living humans are patrilineally descended. As the identity of both matrilineal and patrilineal MRCAs is dependent on genealogical history (pedigree collapse), they need not have lived at the same time. As of 2015, estimates of the age of the Y-MRCA range around 200,000 to 300,000 years ago, roughly consistent with the emergence of anatomically modern humans.

The name "Mitochondrial Eve" alludes to the biblical Eve, which has led to repeated misrepresentations or misconceptions in journalistic accounts on the topic. Popular science presentations of the topic usually point out such possible misconceptions by emphasizing the fact that the position of mt-MRCA is neither fixed in time (as the position of mt-MRCA moves forward in time as mitochondrial DNA (mtDNA) lineages become extinct), nor does it refer to a "first woman", nor the only living female of her time, nor the first member of a "new species".

🔗 United States 🔗 Computing 🔗 Computing/Computer hardware 🔗 Plan 9

The AT&T Hobbit is a microprocessor design that AT&T Corporation developed in the early 1990s. It was based on the company's CRISP (C-language Reduced Instruction Set Processor) design, which in turn grew out of Bell Labs' C Machine design of the late 1980s. C Machine, CRISP and Hobbit were optimized for running the C programming language. The design concentrated on fast instruction decoding, indexed array access and procedure calls. Its processor was partially RISC-like. The project ended in 1994 because the Hobbit failed to achieve commercially viable sales.

🔗 United States 🔗 United States/North Carolina 🔗 Appalachia 🔗 Tennessee

In the Appalachian Mountains of the eastern United States, balds are mountain summits or crests covered primarily by thick vegetation of native grasses or shrubs occurring in areas where heavy forest growth would be expected.

Balds are found primarily in the Southern Appalachians, where, even at the highest elevations, the climate is too warm to support an alpine zone, areas where trees fail to grow due to short or non-existent growing seasons. The difference between an alpine summit, such as Mount Washington in New Hampshire, and a bald, such as Gregory Bald in the Great Smoky Mountains, is that a lack of trees is normal for the colder climate of the former but abnormal for the warmer climate of the latter. One example of southern balds' abnormality can be found at Roan Mountain, where Roan High Knob (el. 6,285 ft/1,915 m) is coated with a dense stand of spruce-fir forest, whereas an adjacent summit, Round Bald (el. 5,826 ft/1,776 m), is almost entirely devoid of trees. Why some summits are bald and some are not is a mystery, though there are several hypotheses.

🔗 Mathematics

In combinatorial mathematics, the ménage problem or problème des ménages asks for the number of different ways in which it is possible to seat a set of male-female couples at a round dining table so that men and women alternate and nobody sits next to his or her partner. This problem was formulated in 1891 by Édouard Lucas and independently, a few years earlier, by Peter Guthrie Tait in connection with knot theory. For a number of couples equal to 3, 4, 5, ... the number of seating arrangements is

12, 96, 3120, 115200, 5836320, 382072320, 31488549120, ... (sequence A059375 in the OEIS).

Mathematicians have developed formulas and recurrence equations for computing these numbers and related sequences of numbers. Along with their applications to etiquette and knot theory, these numbers also have a graph theoretic interpretation: they count the numbers of matchings and Hamiltonian cycles in certain families of graphs.