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Descent
Descent may refer to: As a noun Genealogy and inheritance * Common descent, concept in evolutionary biology * Kinship, one of the major concepts of cultural anthropology ** Pedigree chart or family tree **Ancestry **Lineal descendant ** Heritage ** Royal descent - lineal descent from a monarch * Phylogenetics **Tree diagram (other) * Inheritance (law and property) Mathematics * Infinite descent, a method going back to Fermat to solve Diophantine equations * Descent (mathematics), an idea extending the notion of "gluing" in topology * Hadamard's method of descent, a technique for solving partial differential equations * Gradient descent, a first-order optimization algorithm going back to Newton * Descents in permutations, a classical permutation statistic in combinatorics Other uses * Descent (aeronautics), the decrease of an aircraft in altitude during flight * Descent (font), the distance that a typeface descends below the baseline in typography * Katabasis As a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gradient Descent
In mathematics, gradient descent (also often called steepest descent) is a first-order iterative optimization algorithm for finding a local minimum of a differentiable function. The idea is to take repeated steps in the opposite direction of the gradient (or approximate gradient) of the function at the current point, because this is the direction of steepest descent. Conversely, stepping in the direction of the gradient will lead to a local maximum of that function; the procedure is then known as gradient ascent. Gradient descent is generally attributed to Augustin-Louis Cauchy, who first suggested it in 1847. Jacques Hadamard independently proposed a similar method in 1907. Its convergence properties for non-linear optimization problems were first studied by Haskell Curry in 1944, with the method becoming increasingly well-studied and used in the following decades. Description Gradient descent is based on the observation that if the multi-variable function F(\mathbf) is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinship
In anthropology, kinship is the web of social relationships that form an important part of the lives of all humans in all societies, although its exact meanings even within this discipline are often debated. Anthropologist Robin Fox says that the study of kinship is the study of what humans do with these basic facts of lifemating, gestation, parenthood, socialization, siblingship etc. Human society is unique, he argues, in that we are "working with the same raw material as exists in the animal world, but ecan conceptualize and categorize it to serve social ends." These social ends include the socialization of children and the formation of basic economic, political and religious groups. Kinship can refer both to the patterns of social relationships themselves, or it can refer to the study of the patterns of social relationships in one or more human cultures (i.e. kinship studies). Over its history, anthropology has developed a number of related concepts and terms in the st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Descent 3
''Descent 3'' (stylized as ''Descent³'') is a first-person shooter video game developed by Outrage Entertainment and published by Interplay Entertainment. It was originally released for Microsoft Windows in North America on June 17, 1999. ''Descent 3'' is the third game in the ''Descent'' video game series and a sequel to ''Descent II''. The game takes place in a science fiction setting of the Solar System where the player is cast as Material Defender, a mercenary who must help an organization known as the Red Acropolis Research Team to stop robots infected by an alien Computer virus, virus. Unlike in standard first-person shooters, the player must control a flying ship that has a six degrees of freedom movement scheme, allowing the player to move and rotate in any Three-dimensional space, 3D direction. In addition to a Single-player video game, single-player campaign mode, ''Descent 3'' features an Computer network, online Multiplayer video game, multiplayer mode where numerous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Descent
A royal descent is a genealogical line of descent from a past or present monarch. Both geneticists and genealogists have attempted to estimate the percentage of living people with royal descent. From a genetic perspective, the number of unprovable descendants must be virtually unlimited if going back enough generations, according to coalescent theory, as the possibility increases exponentially following every century back in time. In other words, the number of descendants from a monarch increases as a function of the length of time between the monarch's death and the birth of the particular descendant. As for descendants of genealogically documented royal descent, various estimated figures have been proposed. For instance, Mark Humphrys, a professor of computer science at Dublin City University in Ireland, and genealogy enthusiast, estimated that there are millions of people of provable genealogical ancestry from medieval monarchs. In genealogy, royal descent is sometimes c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Descent II
''Descent II'' is a 1996 first-person shooter game developed by Parallax Software and first published for DOS by Interplay Productions. For the PlayStation, it is known as ''Descent Maximum''. It is the second installment in the ''Descent'' video game series and the sequel to '' Descent''. The base of the gameplay remaining the same, the player controls a spaceship from the pilot's perspective and must navigate extrasolar underground mines to locate and destroy their reactors and escape being caught in their self-destructions, while engaging and surviving infected robots, which will attempt to destroy the ship. Unlike other first-person shooters, its six-degrees-of-freedom scheme allows the player to move and rotate in any three-dimensional space and direction. ''Descent II''s development started as a project intended to expand the original using a compact disc's storage, which later became a standalone product. The game received very positive reviews from video game crit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Descent (video Game)
''Descent'' is a first-person shooter (FPS) game developed by Parallax Software and released by Interplay Productions in 1995 for MS-DOS, and later for Macintosh, PlayStation, and RISC OS. It popularized a subgenre of FPS games employing six degrees of freedom and was the first FPS to feature entirely true-3D graphics. The player is cast as a mercenary hired to eliminate the threat of a mysterious extraterrestrial computer virus infecting off-world mining robots. In a series of mines throughout the Solar System, the protagonist pilots a spaceship and must locate and destroy the mine's power reactor and escape before being caught in the mine's self-destruction, defeating opposing robots along the way. Players can play online and compete in either deathmatches or cooperate to take on the robots. ''Descent'' was a commercial success. Together with its sequel, it sold over 1.1 million units as of 1998 and was critically acclaimed. Commentators and reviewers compared it to '' Doo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infinite Descent
In mathematics, a proof by infinite descent, also known as Fermat's method of descent, is a particular kind of proof by contradiction used to show that a statement cannot possibly hold for any number, by showing that if the statement were to hold for a number, then the same would be true for a smaller number, leading to an infinite descent and ultimately a contradiction. It is a method which relies on the well-ordering principle, and is often used to show that a given equation, such as a Diophantine equation, has no solutions. Typically, one shows that if a solution to a problem existed, which in some sense was related to one or more natural numbers, it would necessarily imply that a second solution existed, which was related to one or more 'smaller' natural numbers. This in turn would imply a third solution related to smaller natural numbers, implying a fourth solution, therefore a fifth solution, and so on. However, there cannot be an infinity of ever-smaller natural numbers, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Descent (aeronautics)
In aeronautics, a descent is any time period during air travel where an aircraft decreases altitude, and is the opposite of an ''ascent'' or '' climb''. Descents are part of normal procedures, but also occur during emergencies, such as rapid or explosive decompression, forcing an emergency descent to below and preferably below , respectively the maximum temporary safe altitude for an unpressurized aircraft and the maximum safe altitude for extended duration. An example of explosive decompression is Aloha Airlines Flight 243. Involuntary descent might occur from a decrease in power, decreased lift (wing icing), an increase in drag, or flying in an air mass moving downward, such as a terrain induced downdraft, near a thunderstorm, in a downburst, or microburst. Normal descents Intentional descents might be undertaken to land, avoid other air traffic or poor flight conditions (turbulence, icing conditions, or bad weather), clouds (particularly under visual flight rules), to see ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Descent
Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. All living beings are in fact descendants of a unique ancestor commonly referred to as the last universal common ancestor (LUCA) of all life on Earth, according to modern evolutionary biology. Common descent is an effect of speciation, in which multiple species derive from a single ancestral population. The more recent the ancestral population two species have in common, the more closely are they related. The most recent common ancestor of all currently living organisms is the last universal ancestor, which lived about 3.9 billion years ago. The two earliest pieces of evidence for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in western Greenland and microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. All currently living organisms on Earth s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Descent
''The Descent'' is a 2005 British horror film written and directed by Neil Marshall. The film follows six women who enter a cave system and struggle to survive against the humanoid creatures inside. Filming took place in the United Kingdom. Exterior scenes were filmed at Ashridge Park, Hertfordshire, and in Scotland. Because the filmmakers considered it too dangerous and time-consuming to shoot in an actual cave, interior scenes were filmed on sets built at Pinewood Studios near London designed by Simon Bowles. ''The Descent'' opened in cinemas in the United Kingdom on 8 July 2005. It premiered in the 2006 Sundance Film Festival and released on 4 August 2006 in the United States. The film received positive reviews and was a box-office success, grossing $57.1 million against a £3.5 million budget. A sequel, titled '' The Descent Part 2'', directed by the first film's editor Jon Harris, was released in 2009. Plot Thrill seeker friends Sarah, Juno, and Beth whitewater raft t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Descent (mathematics)
In mathematics, the idea of descent extends the intuitive idea of 'gluing' in topology. Since the topologists' glue is the use of equivalence relations on topological spaces, the theory starts with some ideas on identification. Descent of vector bundles The case of the construction of vector bundles from data on a disjoint union of topological spaces is a straightforward place to start. Suppose ''X'' is a topological space covered by open sets ''Xi''. Let ''Y'' be the disjoint union of the ''Xi'', so that there is a natural mapping :p: Y \rightarrow X. We think of ''Y'' as 'above' ''X'', with the ''Xi'' projection 'down' onto ''X''. With this language, ''descent'' implies a vector bundle on ''Y ''(so, a bundle given on each ''Xi''), and our concern is to 'glue' those bundles ''Vi'', to make a single bundle ''V'' on X. What we mean is that ''V'' should, when restricted to ''Xi'', give back ''Vi'', up to a bundle isomorphism. The data needed is then this: on each overlap :X_ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family Tree
A family tree, also called a genealogy or a pedigree chart, is a chart representing family relationships in a conventional tree structure. More detailed family trees, used in medicine and social work, are known as genograms. Representations of family history Genealogical data can be represented in several formats, for example, as a pedigree or . Family trees are often presented with the oldest generations at the top of the tree and the younger generations at the bottom. An ancestry chart, which is a tree showing the ancestors of an individual and not all members of a family, will more closely resemble a tree in shape, being wider at the top than at the bottom. In some ancestry charts, an individual appears on the left and his or her ancestors appear to the right. Conversely, a descendant chart, which depicts all the descendants of an individual, will be narrowest at the top. Beyond these formats, some family trees might include all members of a particular surname (e.g., male- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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