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Lists Of Unsolved Problems
List of unsolved problems may refer to several notable conjectures or open problems in various academic fields: Natural sciences, engineering and medicine * Unsolved problems in astronomy * Unsolved problems in biology * Unsolved problems in chemistry * Unsolved problems in engineering * Unsolved problems in geoscience * Unsolved problems in medicine * Unsolved problems in neuroscience * Unsolved problems in physics Mathematics, philosophy and information sciences * Unsolved problems in mathematics * Unsolved problems in statistics * Unsolved problems in computer science * Unsolved problems in philosophy * Unsolved problems in information theory Social sciences and languages * Unsolved problems in economics * Unsolved problems in fair division * Unsolved problems in linguistics See also * Cold case (unsolved crimes) * List of ciphertexts * List of NP-complete problems * List of PSPACE-complete problems * List of paradoxes * List of undecidable problems * List of unsolve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Conjectures
This is a list of mathematical conjectures. Open problems The following conjectures remain open. The (incomplete) column "cites" lists the number of results for a Google Scholar search for the term, in double quotes . Conjectures now proved (theorems) The conjecture terminology may persist: theorems often enough may still be referred to as conjectures, using the anachronistic names. * Deligne's conjecture on 1-motives * Goldbach's weak conjecture (proved in 2013) * Sensitivity conjecture (proved in 2019) Disproved (no longer conjectures) * Atiyah conjecture (not a conjecture to start with) * Borsuk's conjecture * Chinese hypothesis (not a conjecture to start with) * Doomsday conjecture * Euler's sum of powers conjecture * Ganea conjecture * Generalized Smith conjecture * Hauptvermutung * Hedetniemi's conjecture, counterexample announced 2019 * Hirsch conjecture (disproved in 2010) * Intersection graph conjecture * Kelvin's conjecture * Kouchnirenko's conjecture * Merten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Unsolved Problems In Economics
This is a list of some of the major unsolved problems, puzzles, or questions in economics. Some of these are theoretical in origin and some of them concern the inability of orthodox economic theory to explain an empirical observation. Capital theory *Cambridge capital controversy: The Cambridge capital controversy is a dispute in economics that started in the 1950s. The debate concerned the nature and role of capital goods and a critique of the neoclassical vision of aggregate production and distribution. The question of whether the natural growth rate is exogenous, or endogenous to demand (and whether it is input growth that causes output growth, or vice versa), lies at the heart of the debate. The resolution of the debate has not been agreed upon by economists. *Transformation problem: The transformation problem is the problem specific to Marxist economics, and not to economics in general, of finding a general rule by which to transform the values of commodities based on sociall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Problems
In science and mathematics, an open problem or an open question is a known problem which can be accurately stated, and which is assumed to have an objective and verifiable solution, but which has not yet been solved (i.e., no solution for it is known). In the history of science, some of these supposed open problems were "solved" by means of showing that they were not well-defined. In mathematics, many open problems are concerned with the question of whether a certain definition is or is not consistent. Two notable examples in mathematics that have been solved and ''closed'' by researchers in the late twentieth century are Fermat's Last Theorem and the four-color theorem.K. Appel and W. Haken (1977), "Every planar map is four colorable. Part I. Discharging", ''Illinois J. Math'' 21: 429–490. K. Appel, W. Haken, and J. Koch (1977), "Every planar map is four colorable. Part II. Reducibility", ''Illinois J. Math'' 21: 491–567. An important open mathematics problem solved i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lists Of Unsolved Problems
List of unsolved problems may refer to several notable conjectures or open problems in various academic fields: Natural sciences, engineering and medicine * Unsolved problems in astronomy * Unsolved problems in biology * Unsolved problems in chemistry * Unsolved problems in engineering * Unsolved problems in geoscience * Unsolved problems in medicine * Unsolved problems in neuroscience * Unsolved problems in physics Mathematics, philosophy and information sciences * Unsolved problems in mathematics * Unsolved problems in statistics * Unsolved problems in computer science * Unsolved problems in philosophy * Unsolved problems in information theory Social sciences and languages * Unsolved problems in economics * Unsolved problems in fair division * Unsolved problems in linguistics See also * Cold case (unsolved crimes) * List of ciphertexts * List of NP-complete problems * List of PSPACE-complete problems * List of paradoxes * List of undecidable problems * List of unsolve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lists Of Problems
The following articles contain lists of problems: *List of undecidable problems *Lists of unsolved problems *List of NP-complete problems *List of PSPACE-complete problems Here are some of the more commonly known problems that are PSPACE-complete when expressed as decision problems. This list is in no way comprehensive. Games and puzzles Generalized versions of: * Amazons * Atomix * Checkers * Dyson Telesc ... {{DEFAULTSORT:Problems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Unsolved Deaths
This list of unsolved deaths includes well-known cases where: * The cause of death could not be officially determined. * The person's identity could not be established after they were found dead. * The cause is known, but the manner of death (homicide, suicide, accident, overdosing) could not be determined. * Different official investigations have come to different conclusions. Cases where there are unofficial alternative theories about deaths – the most common theory being that the death was a homicide – can be found under: Death conspiracy theories. Unsolved murders Unsolved deaths Ancient * Cleopatra (39), the last ruler of Ptolemaic Egypt, is believed to have died in August 30 BCE in Alexandria. According to popular belief, Cleopatra committed suicide by allowing an asp (Egyptian cobra) to bite her. According to Greek and Roman historians, Cleopatra poisoned herself using either a toxic ointment or sharp implement such as a hairpin. Primary source accounts are derive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Undecidable Problems
In computability theory, an undecidable problem is a type of computational problem that requires a yes/no answer, but where there cannot possibly be any computer program that always gives the correct answer; that is, any possible program would sometimes give the wrong answer or run forever without giving any answer. More formally, an undecidable problem is a problem whose language is not a recursive set; see the article Decidable language. There are uncountably many undecidable problems, so the list below is necessarily incomplete. Though undecidable languages are not recursive languages, they may be subsets of Turing recognizable languages: i.e., such undecidable languages may be recursively enumerable. Many, if not most, undecidable problems in mathematics can be posed as word problems: determining when two distinct strings of symbols (encoding some mathematical concept or object) represent the same object or not. For undecidability in axiomatic mathematics, see List of stateme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Paradoxes
This list includes well known paradoxes, grouped thematically. The grouping is approximate, as paradoxes may fit into more than one category. This list collects only scenarios that have been called a paradox by at least one source and have their own article in this encyclopedia. Although considered paradoxes, some of these are simply based on fallacious reasoning ( falsidical), or an unintuitive solution (veridical). Informally, the term ''paradox'' is often used to describe a counter-intuitive result. However, some of these paradoxes qualify to fit into the mainstream perception of a paradox, which is a self-contradictory result gained even while properly applying accepted ways of reasoning. These paradoxes, often called ''antinomy,'' point out genuine problems in our understanding of the ideas of truth and description. Logic * : The supposition that, 'if one of two simultaneous assumptions leads to a contradiction, the other assumption is also disproved' leads to paradoxical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of PSPACE-complete Problems
Here are some of the more commonly known problems that are PSPACE-complete when expressed as decision problems. This list is in no way comprehensive. Games and puzzles Generalized versions of: * Amazons * Atomix * Checkers * Dyson Telescope Game * Cross Purposes * Geography * Two-player game version of Instant Insanity * Ko-free Go * Ladder capturing in GoGo ladders are PSPACE-complete * * Hex * Konane * |
List Of NP-complete Problems
This is a list of some of the more commonly known problems that are NP-complete when expressed as decision problems. As there are hundreds of such problems known, this list is in no way comprehensive. Many problems of this type can be found in . Graphs and hypergraphs Graphs occur frequently in everyday applications. Examples include biological or social networks, which contain hundreds, thousands and even billions of nodes in some cases (e.g. Facebook or LinkedIn). * 1-planarity *3-dimensional matching * Bandwidth problem *Bipartite dimension * Capacitated minimum spanning tree *Route inspection problem (also called Chinese postman problem) for mixed graphs (having both directed and undirected edges). The program is solvable in polynomial time if the graph has all undirected or all directed edges. Variants include the rural postman problem. * Clique cover problem *Clique problem *Complete coloring, a.k.a. achromatic number *Cycle rank a.k.a. Rank coloring * Degree-constrained s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Ciphertexts
Some famous ciphertexts (or cryptograms), in chronological order by date, are: See also * Undeciphered writing systems (cleartext, natural-language writing of unknown meaning) External links * Elonka Dunin Elonka Dunin (; born December 29, 1958) is an American video game developer and cryptologist. Dunin worked at Simutronics Corp. in St. Louis, Missouri from 1990–2014, and in 2015 was Senior Producer at Black Gate Games in Nashville, Tenne ...'list of famous unsolved codes and ciphers {{DEFAULTSORT:Ciphertexts Cryptography lists and comparisons History of cryptography Undeciphered historical codes and ciphers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Case
A cold case is a crime, or a suspected crime, that has not yet been fully resolved and is not the subject of a current criminal investigation, but for which new information could emerge from new witness testimony, re-examined archives, new or retained material evidence, or fresh activities of a suspect. New technological methods developed after the crime was committed can be used on the surviving evidence to analyse causes, often with conclusive results. Characteristics Violent or major crime Typically, cold cases are violent and other major felony crimes, such as murder and rape, which—unlike unsolved minor crimes—are generally not subject to a statute of limitations. Sometimes disappearances can also be considered cold cases if the victim has not been seen or heard from for some time, such as the case of Natalee Holloway or the Beaumont children. About 35% of those cases are not cold cases at all. Some cases become instantly cold when a seeming closed (solved) case is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
