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Inside–outside Algorithm
For Parsing, parsing algorithms in computer science, the inside–outside algorithm is a way of re-estimating production probabilities in a probabilistic context-free grammar. It was introduced by James K. Baker in 1979 as a generalization of the forward–backward algorithm for parameter estimation on hidden Markov models to stochastic context-free grammars. It is used to compute expectations, for example as part of the expectation–maximization algorithm (an unsupervised learning algorithm). Inside and outside probabilities The inside probability \beta_j(p,q) is the total probability of generating words w_p \cdots w_q, given the root nonterminal N^j and a grammar G: :\beta_j(p,q) = P(w_, N^j_, G) The outside probability \alpha_j(p,q) is the total probability of beginning with the start symbol N^1 and generating the nonterminal N^j_ and all the words outside w_p \cdots w_q, given a grammar G: :\alpha_j(p,q) = P(w_, N^j_, w_, G) Computing inside probabilities Base Case: \beta_j( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parsing
Parsing, syntax analysis, or syntactic analysis is a process of analyzing a String (computer science), string of Symbol (formal), symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar by breaking it into parts. The term ''parsing'' comes from Latin ''pars'' (''orationis''), meaning Part of speech, part (of speech). The term has slightly different meanings in different branches of linguistics and computer science. Traditional Sentence (linguistics), sentence parsing is often performed as a method of understanding the exact meaning of a sentence or word, sometimes with the aid of devices such as sentence diagrams. It usually emphasizes the importance of grammatical divisions such as subject (grammar), subject and predicate (grammar), predicate. Within computational linguistics the term is used to refer to the formal analysis by a computer of a sentence or other string of words into its constituents, resulting in a par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Probabilistic Context-free Grammar
In theoretical linguistics and computational linguistics, probabilistic context free grammars (PCFGs) extend context-free grammars, similar to how hidden Markov models extend regular grammars. Each production is assigned a probability. The probability of a derivation (parse) is the product of the probabilities of the productions used in that derivation. These probabilities can be viewed as parameters of the model, and for large problems it is convenient to learn these parameters via machine learning. A probabilistic grammar's validity is constrained by context of its training dataset. PCFGs originated from grammar theory, and have application in areas as diverse as natural language processing to the study the structure of RNA molecules and design of programming languages. Designing efficient PCFGs has to weigh factors of scalability and generality. Issues such as grammar ambiguity must be resolved. The grammar design affects results accuracy. Grammar parsing algorithms have various ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James K
James may refer to: People * James (given name) * James (surname) * James (musician), aka Faruq Mahfuz Anam James, (born 1964), Bollywood musician * James, brother of Jesus * King James (other), various kings named James * Prince James (other) * Saint James (other) Places Canada * James Bay, a large body of water * James, Ontario United Kingdom * James College, a college of the University of York United States * James, Georgia, an unincorporated community * James, Iowa, an unincorporated community * James City, North Carolina * James City County, Virginia ** James City (Virginia Company) ** James City Shire * James City, Pennsylvania * St. James City, Florida Film and television * ''James'' (2005 film), a Bollywood film * ''James'' (2008 film), an Irish short film * ''James'' (2022 film), an Indian Kannada-language film * "James", a television episode of ''Adventure Time'' Music * James (band), a band from Manchester ** ''James'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forward–backward Algorithm
The forward–backward algorithm is an inference algorithm for hidden Markov models which computes the posterior probability, posterior marginal probability, marginals of all hidden state variables given a sequence of observations/emissions o_:= o_1,\dots,o_T, i.e. it computes, for all hidden state variables X_t \in \, the distribution P(X_t\ , \ o_). This inference task is usually called smoothing. The algorithm makes use of the principle of dynamic programming to efficiently compute the values that are required to obtain the posterior marginal distributions in two passes. The first pass goes forward in time while the second goes backward in time; hence the name ''forward–backward algorithm''. The term ''forward–backward algorithm'' is also used to refer to any algorithm belonging to the general class of algorithms that operate on sequence models in a forward–backward manner. In this sense, the descriptions in the remainder of this article refer only to one specific insta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hidden Markov Model
A hidden Markov model (HMM) is a Markov model in which the observations are dependent on a latent (or ''hidden'') Markov process (referred to as X). An HMM requires that there be an observable process Y whose outcomes depend on the outcomes of X in a known way. Since X cannot be observed directly, the goal is to learn about state of X by observing Y. By definition of being a Markov model, an HMM has an additional requirement that the outcome of Y at time t = t_0 must be "influenced" exclusively by the outcome of X at t = t_0 and that the outcomes of X and Y at t < t_0 must be conditionally independent of at given at time . Estimation of the parameters in an HMM can be performed using maximum likelihood estimation. For linear chain HMMs, the Baum–Welch algorithm can be used to estimate parameters. Hidden Markov models are known for their applications to thermodynamics, statistical mechanics, physics, chem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stochastic Context-free Grammar
In theoretical linguistics and computational linguistics, probabilistic context free grammars (PCFGs) extend context-free grammars, similar to how hidden Markov models extend regular grammars. Each Formal grammar#The syntax of grammars, production is assigned a probability. The probability of a derivation (parse) is the product of the probabilities of the productions used in that derivation. These probabilities can be viewed as parameters of the model, and for large problems it is convenient to learn these parameters via machine learning. A probabilistic grammar's validity is constrained by context of its training dataset. PCFGs originated from grammar theory, and have application in areas as diverse as natural language processing to the study the structure of RNA molecules and design of programming languages. Designing efficient PCFGs has to weigh factors of scalability and generality. Issues such as grammar ambiguity must be resolved. The grammar design affects results accuracy. Gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expectation–maximization Algorithm
In statistics, an expectation–maximization (EM) algorithm is an iterative method to find (local) maximum likelihood or maximum a posteriori (MAP) estimates of parameters in statistical models, where the model depends on unobserved latent variables. The EM iteration alternates between performing an expectation (E) step, which creates a function for the expectation of the log-likelihood evaluated using the current estimate for the parameters, and a maximization (M) step, which computes parameters maximizing the expected log-likelihood found on the ''E'' step. These parameter-estimates are then used to determine the distribution of the latent variables in the next E step. It can be used, for example, to estimate a mixture of gaussians, or to solve the multiple linear regression problem. History The EM algorithm was explained and given its name in a classic 1977 paper by Arthur Dempster, Nan Laird, and Donald Rubin. They pointed out that the method had been "proposed man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karim Lari
Kareem (alternatively spelled Karim, Kerim or Karem) () is a given name and surname of Arabic origin that means "generous", "noble", "honourable". It is also one of the Names of God. Given name Karim * Karim Abdel Aziz (born 1975), Egyptian actor * Karim Abdul-Jabbar (later known as Abdul-Karim al-Jabbar) (born 1974), American football player * Prince Karim Aga Khan (1936–2025), Imām of the Shia Imami Ismaili Muslims * Karim Valiyev (born 1961), Azerbaijani General * Karim Ansarifard (born 1990), Iranian football player * Karim Azizou (born 1985), Moroccan footballer * Karim Bagheri (born 1974), Iranian footballer * Karim Bangoura (1926–1972), Guinean diplomat * Karim Benounes(born 1984), Algerian footballer * Karim Benzema (born 1987), French footballer * Karim Boudiaf (born 1990), Algerian-Qatari footballer * Karim Dahou (born 1982), Moroccan footballer * Karim Dembélé (1939–2010), Malian soldier and politician * Karim Djeballi (born 1983), French footballer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steve J
Steve is a masculine given name, usually a short form (hypocorism) of Steven or Stephen. Notable people A–D * Steve Abbott (other), several people * Steve Abel (born 1970), New Zealand politician * Steve Adams (other), several people * Steve Addabbo, American record producer, songwriter and audio engineer * Steve Agee (born 1969), American comedian, actor, writer and musician * Steve Agnew (born 1965), English football coach and former professional football player * Steve Alaimo (1939–2024), American singer, record & TV producer, label owner * Steve Albini (1961–2024), American musician, record producer, audio engineer, and music journalist * Steve Allen (1921–2000), American television personality, musician, composer, comedian and writer * Steve Allrich, American screenwriter and painter * Steve Alten (born 1959), American science-fiction author * Steve Anthony (born 1959), Canadian former broadcaster * Steve Anthony (wrestler) (born 1977), Ameri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
