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Two Generals' Problem
In computing, the Two Generals' Problem is a thought experiment meant to illustrate the pitfalls and design challenges of attempting to coordinate an action by communicating over an unreliable link. In the experiment, two generals are only able to communicate with one another by sending a messenger through enemy territory. The experiment asks how they might reach an agreement on the time to launch an attack, while knowing that any messenger they send could be captured. The Two Generals' Problem appears often as an introduction to the more general Byzantine Generals problem in introductory classes about computer networking (particularly with regard to the Transmission Control Protocol, where it shows that TCP cannot guarantee state consistency between endpoints and why this is the case), though it applies to any type of two-party communication where failures of communication are possible. A key concept in epistemic logic, this problem highlights the importance of common knowledge. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Imperial College London
Imperial College London, also known as Imperial, is a Public university, public research university in London, England. Its history began with Prince Albert of Saxe-Coburg and Gotha, Prince Albert, husband of Queen Victoria, who envisioned a Albertopolis, cultural district in South Kensington that included museums, colleges, and the Royal Albert Hall. In 1907, these colleges – the Royal College of Science, the Royal School of Mines, and the City and Guilds of London Institute – merged to form the Imperial College of Science and Technology. In 1988, Imperial merged with St Mary's Hospital, London, St Mary's Hospital Medical School and then with Charing Cross and Westminster Medical School to form the Imperial College School of Medicine. The Imperial Business School was established in 2003 and officially opened by Elizabeth II, Queen Elizabeth II. Formerly a constituent college of the University of London, Imperial became an independent university in 2007. Imperial is o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Distributed Computing Problems
Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a variable **Cumulative distribution function, in which the probability of being no greater than a particular value is a function of that value *Frequency distribution, a list of the values recorded in a sample * Inner distribution, and outer distribution, in coding theory *Distribution (differential geometry), a subset of the tangent bundle of a manifold * Distributed parameter system, systems that have an infinite-dimensional state-space * Distribution of terms, a situation in which all members of a category are accounted for *Distributivity, a property of binary operations that generalises the distributive law from elementary algebra *Distribution (number theory) *Distribution problems, a common type of problems in combinatorics where the goa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Consensus Algorithm
A fundamental problem in distributed computing and multi-agent systems is to achieve overall system reliability in the presence of a number of faulty processes. This often requires coordinating processes to reach consensus, or agree on some data value that is needed during computation. Example applications of consensus include agreeing on what transactions to commit to a database in which order, state machine replication, and atomic broadcasts. Real-world applications often requiring consensus include cloud computing, clock synchronization, PageRank, opinion formation, Smart grid, smart power grids, state estimation, Unmanned aerial vehicle, control of UAVs (and multiple robots/agents in general), Load balancing (computing), load balancing, blockchain, and others. Problem description The consensus problem requires agreement among a number of processes (or agents) on a single data value. Some of the processes (agents) may fail or be unreliable in other ways, so consensus protocols mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Jim Gray (computer Scientist)
James Nicholas Gray (1944 – declared dead in absentia 2012) was an American computer scientist who received the Turing Award in 1998 "for seminal contributions to database and transaction processing research and technical leadership in system implementation". Early years and personal life Gray was born in San Francisco, the second child of Ann Emma Sanbrailo, a teacher, and James Able Gray, who was in the U.S. Army; the family moved to Rome, Italy, where Gray spent most of the first three years of his life; he learned to speak Italian before English. The family then moved to Virginia, spending about four years there, until Gray's parents divorced, after which he returned to San Francisco with his mother. His father, an amateur inventor, patented a design for a ribbon cartridge for typewriters that earned him a substantial royalty stream. After being turned down for the Air Force Academy he entered the University of California, Berkeley as a freshman in 1961. To help pay for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Communication
Communication is commonly defined as the transmission of information. Its precise definition is disputed and there are disagreements about whether Intention, unintentional or failed transmissions are included and whether communication not only transmits semantics, meaning but also creates it. Models of communication are simplified overviews of its main components and their interactions. Many models include the idea that a source uses a code, coding system to express information in the form of a message. The message is sent through a Communication channel, channel to a receiver who has to decode it to understand it. The main field of inquiry investigating communication is called communication studies. A common way to classify communication is by whether information is exchanged between humans, members of other species, or non-living entities such as computers. For human communication, a central contrast is between Verbal communication, verbal and non-verbal communication. Verba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Uncertainty
Uncertainty or incertitude refers to situations involving imperfect or unknown information. It applies to predictions of future events, to physical measurements that are already made, or to the unknown, and is particularly relevant for decision-making. Uncertainty arises in partially observable or stochastic environments, as well as due to ignorance, Laziness, indolence, or both. It arises in any number of fields, including insurance, philosophy, physics, statistics, economics, finance, medicine, psychology, sociology, engineering, metrology, meteorology, ecology and information science. Concepts Although the terms are used in various ways among the general public, many specialists in decision theory, statistics and other quantitative fields have defined uncertainty, risk, and their measurement as: Uncertainty The lack of certainty, a state of limited knowledge where it is impossible to exactly describe the existing state, a future outcome, or more than one possible outcome. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Tree (graph Theory)
In graph theory, a tree is an undirected graph in which any two vertices are connected by path, or equivalently a connected acyclic undirected graph. A forest is an undirected graph in which any two vertices are connected by path, or equivalently an acyclic undirected graph, or equivalently a disjoint union of trees. A directed tree, oriented tree,See .See . polytree,See . or singly connected networkSee . is a directed acyclic graph (DAG) whose underlying undirected graph is a tree. A polyforest (or directed forest or oriented forest) is a directed acyclic graph whose underlying undirected graph is a forest. The various kinds of data structures referred to as trees in computer science have underlying graphs that are trees in graph theory, although such data structures are generally rooted trees. A rooted tree may be directed, called a directed rooted tree, either making all its edges point away from the root—in which case it is called an arborescence or out-tree� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Deterministic System
In mathematics, computer science and physics, a deterministic system is a system in which no randomness is involved in the development of future states of the system. A deterministic model will thus always produce the same output from a given starting condition or initial state. In physics Physical laws that are described by differential equations represent deterministic systems, even though the state of the system at a given point in time may be difficult to describe explicitly. In quantum mechanics, the Schrödinger equation, which describes the continuous time evolution of a system's wave function, is deterministic. However, the relationship between a system's wave function and the observable properties of the system appears to be non-deterministic. In mathematics The systems studied in chaos theory are deterministic. If the initial state were known exactly, then the future state of such a system could theoretically be predicted. However, in practice, knowledge about the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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SRI International
SRI International (SRI) is a nonprofit organization, nonprofit scientific research, scientific research institute and organization headquartered in Menlo Park, California, United States. It was established in 1946 by trustees of Stanford University to serve as a center of innovation to support economic development in the region. The organization was founded as the Stanford Research Institute. SRI formally separated from Stanford University in 1970 and became known as SRI International in 1977. SRI performs client-sponsored research and development for government agencies, commercial businesses, and private foundations. It also licenses its technologies, forms strategic partnerships, sells products, and creates Research spin-off, spin-off companies. SRI's headquarters are located near the Stanford University campus. SRI's annual revenue in 2014 was approximately $540 million, which tripled from 1998 under the leadership of Curtis Carlson. In 1998, the organization was on the ver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Consensus (computer Science)
A fundamental problem in distributed computing and multi-agent systems is to achieve overall system reliability in the presence of a number of faulty processes. This often requires coordinating processes to reach consensus, or agree on some data value that is needed during computation. Example applications of consensus include agreeing on what transactions to commit to a database in which order, state machine replication, and atomic broadcasts. Real-world applications often requiring consensus include cloud computing, clock synchronization, PageRank, opinion formation, smart power grids, state estimation, control of UAVs (and multiple robots/agents in general), load balancing, blockchain, and others. Problem description The consensus problem requires agreement among a number of processes (or agents) on a single data value. Some of the processes (agents) may fail or be unreliable in other ways, so consensus protocols must be fault-tolerant or resilient. The processes must p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Thought Experiment
A thought experiment is an imaginary scenario that is meant to elucidate or test an argument or theory. It is often an experiment that would be hard, impossible, or unethical to actually perform. It can also be an abstract hypothetical that is meant to test our intuitions about morality or other fundamental philosophical questions. History The ancient Greek , "was the most ancient pattern of mathematical proof", and existed before Euclidean geometry, Euclidean mathematics, where the emphasis was on the conceptual, rather than on the experimental part of a thought experiment. Johann Witt-Hansen established that Hans Christian Ørsted was the first to use the equivalent German term . Ørsted was also the first to use the equivalent term in 1820. By 1883, Ernst Mach used in a different sense, to denote exclusively the conduct of a experiment that would be subsequently performed as a by his students. Physical and mental experimentation could then be contrasted: Mach asked hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |