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Masyu
is a type of logic puzzle designed and published by Nikoli. The purpose of its creation was to present a puzzle that uses no numbers or letters and yet retains depth and aesthetics. Rules ''Masyu'' is played on a rectangular grid of squares, some of which contain circles; each circle is either "white" (empty) or "black" (filled). The goal is to draw a single continuous non-intersecting loop that properly passes through all circled cells. The loop must "enter" each cell it passes through from the center of one of its four sides and "exit" from a different side; all turns are therefore 90 degrees.. The two varieties of circle have differing requirements for ''how'' the loop must pass through them: *White circles must be traveled straight through, but the loop must turn in the previous and/or next cell in its path. *Black circles must be turned upon, but the loop must travel straight through the next and previous cells in its path. Variants *There are additionally or solel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nikoli (publisher)
is a Japanese publisher that specializes in games and, especially, logic puzzles. ''Nikoli'' is also the nickname of a quarterly magazine (whose full name is ''Puzzle Communication Nikoli'') issued by the company in Tokyo. ''Nikoli'' was established in 1980, and became prominent worldwide with the popularity of ''Sudoku''. The name "Nikoli" comes from the racehorse who won the Irish 2,000 Guineas in 1980; the founder of Nikoli, Maki Kaji, was fond of horseracing and betting. Nikoli is notable for its vast library of "culture independent" puzzles. An example of a language/culture-dependent genre of puzzle would be the crossword, which relies on a specific language and alphabet. For this reason Nikoli's puzzles are often purely logical, and often numerical. Nikoli's Sudoku, the most popular logic problem in Japan, was popularized in the English-speaking world in 2005, though that game has a history stretching back hundreds of years and across the globe. The magazine has invent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Phonetic Alphabet
The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standard written representation for the sounds of speech. The IPA is used by linguists, lexicography, lexicographers, foreign language students and teachers, speech–language pathology, speech–language pathologists, singers, actors, constructed language creators, and translators. The IPA is designed to represent those qualities of speech that are part of lexical item, lexical (and, to a limited extent, prosodic) sounds in oral language: phone (phonetics), phones, Intonation (linguistics), intonation and the separation of syllables. To represent additional qualities of speechsuch as tooth wikt:gnash, gnashing, lisping, and sounds made with a cleft lip and cleft palate, cleft palatean extensions to the International Phonetic Alphabet, extended set of symbols may be used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logic Puzzle
A logic puzzle is a puzzle deriving from the mathematics, mathematical field of deductive reasoning, deduction. History The logic puzzle was first produced by Charles Lutwidge Dodgson, who is better known under his pen name Lewis Carroll, the author of ''Alice's Adventures in Wonderland''. In his book ''The Game of Logic'' he introduced a game to solve problems such as confirming the conclusion "Some greyhounds are not fat" from the statements "No fat creatures run well" and "Some greyhounds run well". Puzzles like this, where we are given a list of premises and asked what can be deduced from them, are known as syllogisms. Dodgson goes on to construct much more complex puzzles consisting of up to 8 premises. In the second half of the 20th century mathematician Raymond Smullyan, Raymond M. Smullyan continued and expanded the branch of logic puzzles with books such as ''The Lady or the Tiger?'', ''To Mock a Mockingbird'' and ''Alice in Puzzle-Land''. He popularized the "knights a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree (angle)
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane (mathematics), plane angle in which one Turn (geometry), full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI Brochure, SI brochure as an Non-SI units mentioned in the SI, accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians. History The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Iranian calendar, Persian calendar and the Babylonian calendar, used 360 days for a year. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toroid
In mathematics, a toroid is a surface of revolution with a hole in the middle. The axis of revolution passes through the hole and so does not intersect the surface. For example, when a rectangle is rotated around an axis parallel to one of its edges, then a hollow rectangle-section ring is produced. If the revolved figure is a circle, then the object is called a torus. The term ''toroid'' is also used to describe a toroidal polyhedron. In this context a toroid need not be circular and may have any number of holes. A ''g''-holed ''toroid'' can be seen as approximating the surface of a torus having a topological genus, ''g'', of 1 or greater. The Euler characteristic χ of a ''g'' holed toroid is 2(1−''g''). The torus is an example of a toroid, which is the surface of a doughnut. Doughnuts are an example of a solid torus created by rotating a disk, and are not toroids. Toroidal structures occur in both natural and synthetic materials. Equations A toroid is specified by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kanji
are logographic Chinese characters, adapted from Chinese family of scripts, Chinese script, used in the writing of Japanese language, Japanese. They were made a major part of the Japanese writing system during the time of Old Japanese and are still used, along with the subsequently-derived Syllabary, syllabic scripts of and . The characters have Japanese pronunciations; most have two, with one based on the Chinese sound. A few characters were invented in Japan by constructing character components derived from other Chinese characters. After the Meiji Restoration, Japan made its own efforts to simplify the characters, now known as , by a process similar to China's simplified Chinese characters, simplification efforts, with the intention to increase literacy among the general public. Since the 1920s, the Japanese government has published character lists periodically to help direct the education of its citizenry through the myriad Chinese characters that exist. There are nearly 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jordan Curve Theorem
In topology, the Jordan curve theorem (JCT), formulated by Camille Jordan in 1887, asserts that every ''Jordan curve'' (a plane simple closed curve) divides the plane into an "interior" region Boundary (topology), bounded by the curve (not to be confused with the interior (topology), interior of a set) and an "exterior" region containing all of the nearby and far away exterior points. Every path (topology), continuous path connecting a point of one region to a point of the other intersects with the curve somewhere. While the theorem seems intuitively obvious, it takes some ingenuity to prove it by elementary means. "Although the JCT is one of the best known topological theorems, there are many, even among professional mathematicians, who have never read a proof of it." (). More transparent proofs rely on the mathematical machinery of algebraic topology, and these lead to generalizations to higher-dimensional spaces. The Jordan curve theorem is named after the mathematician Camil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NP-complete
In computational complexity theory, NP-complete problems are the hardest of the problems to which ''solutions'' can be verified ''quickly''. Somewhat more precisely, a problem is NP-complete when: # It is a decision problem, meaning that for any input to the problem, the output is either "yes" or "no". # When the answer is "yes", this can be demonstrated through the existence of a short (polynomial length) ''solution''. # The correctness of each solution can be verified quickly (namely, in polynomial time) and a brute-force search algorithm can find a solution by trying all possible solutions. # The problem can be used to simulate every other problem for which we can verify quickly that a solution is correct. Hence, if we could find solutions of some NP-complete problem quickly, we could quickly find the solutions of every other problem to which a given solution can be easily verified. The name "NP-complete" is short for "nondeterministic polynomial-time complete". In this name, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
