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Chase (algorithm)
The chase is a simple fixed-point algorithm testing and enforcing implication of data dependencies in database systems. It plays important roles in database theory as well as in practice. It is used, directly or indirectly, on an everyday basis by people who design databases, and it is used in commercial systems to reason about the consistency and correctness of a data design. New applications of the chase in meta-data management and data exchange are still being discovered. The chase has its origins in two seminal papers of 1979, one by Alfred V. Aho, Catriel Beeri, and Jeffrey D. Ullman and the other by David Maier, Alberto O. Mendelzon, and Yehoshua Sagiv. In its simplest application the chase is used for testing whether the projection of a relation schema constrained by some functional dependencies onto a given decomposition can be recovered by rejoining the projections. Let ''t'' be a tuple in \pi_(R) \bowtie \pi_(R) \bowtie ... \bowtie \pi_(R) where ''R'' is a relation a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fixed-point Iteration
In numerical analysis, fixed-point iteration is a method of computing fixed points of a function. More specifically, given a function f defined on the real numbers with real values and given a point x_0 in the domain of f, the fixed-point iteration is :x_=f(x_n), \, n=0, 1, 2, \dots which gives rise to the sequence x_0, x_1, x_2, \dots of iterated function applications x_0, f(x_0), f(f(x_0)), \dots which is hoped to converge to a point x_. If f is continuous, then one can prove that the obtained x_ is a fixed point of f, i.e., :f(x_)=x_ . More generally, the function f can be defined on any metric space with values in that same space. Examples * A first simple and useful example is the Babylonian method for computing the square root of ''a''>0, which consists in taking f(x)=\frac 12\left(\frac ax + x\right), i.e. the mean value of ''x'' and ''a/x'', to approach the limit x = \sqrt a (from whatever starting point x_0 \gg 0 ). This is a special case of Newton's method quoted b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Confluence (rewriting System)
In computer science, confluence is a property of rewriting systems, describing which terms in such a system can be rewritten in more than one way, to yield the same result. This article describes the properties in the most abstract setting of an abstract rewriting system. Motivating examples The usual rules of elementary arithmetic form an abstract rewriting system. For example, the expression (11 + 9) × (2 + 4) can be evaluated starting either at the left or at the right parentheses; however, in both cases the same result is eventually obtained. If every arithmetic expression evaluates to the same result regardless of reduction strategy, the arithmetic rewriting system is said to be ground-confluent. Arithmetic rewriting systems may be confluent or only ground-confluent depending on details of the rewriting system. A second, more abstract example is obtained from the following proof of each group element equalling the inverse of its inverse: This proof starts from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jennifer Widom
Jennifer Widom is an American computer scientist known for her work in database systems and data management. She is notable for foundational contributions to semi-structured data management and data stream management systems. Since 2017, Widom is the dean of the School of Engineering and professor of computer science at Stanford University. Her honors include the Fletcher Jones Professor of Computer Science and multiple lifetime achievement awards from the Association for Computing Machinery. Education Widom earned a BS degree in trumpet performance from the Indiana University Jacobs School of Music in 1982 and a PhD in computer science under David Gries from Cornell University in 1987. Academic career Widom began her career as a researcher at the IBM Almaden Research Center and joined Stanford University as a professor in 1993. She was the chair of the Stanford computer science department from 2009 to 2014, and served as senior associate dean for faculty and academ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jeffrey Ullman
Jeffrey David Ullman (born November 22, 1942) is an American computer scientist and the Stanford W. Ascherman Professor of Engineering, Emeritus, at Stanford University. His textbooks on compilers (various editions are popularly known as the dragon book), theory of computation (also known as the Cinderella book), data structures, and databases are regarded as standards in their fields. He and his long-time collaborator Alfred Aho are the recipients of the 2020 Turing Award, generally recognized as the highest distinction in computer science. Career Ullman received a Bachelor of Science degree in engineering mathematics from Columbia University in 1963 and his PhD in electrical engineering from Princeton University in 1966. He then worked for three years at Bell Labs. In 1969, he returned to Princeton as an associate professor, and was promoted to full professor in 1974. Ullman moved to Stanford University in 1979, and served as the department chair from 1990 to 1994. He was n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfred Aho
Alfred Vaino Aho (born August 9, 1941) is a Canadian computer scientist best known for his work on programming languages, compilers, and related algorithms, and his textbooks on the art and science of computer programming. Aho was elected into the National Academy of Engineering in 1999 for his contributions to the fields of algorithms and programming tools. He and his long-time collaborator Jeffrey Ullman are the recipients of the 2020 Turing Award, generally recognized as the highest distinction in computer science. Career Aho received a B.A.Sc. (1963) in Engineering Physics from the University of Toronto, then an M.A. (1965) and Ph.D. (1967) in Electrical Engineering/Computer Science from Princeton University. He conducted research at Bell Labs from 1967 to 1991, and again from 1997 to 2002 as Vice President of the Computing Sciences Research Center. Since 1995, he has held the Lawrence Gussman Professorship in Computer Science at Columbia University. He served as chair of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Victor Vianu
Victor Vianu is a computer scientist, a professor of computer science and engineering at the University of California, San Diego.Faculty profile UCSD, retrieved 2011-03-21. He served as editor-in-chief of the '''' from 2009 to 2015. Vianu did his graduate studies at the , earning his Ph.D. in 1983 under the supervision of Seymour Ginsburg; he joined the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard B
Richard is a male given name. It originates, via Old French, from Old Frankish and is a compound of the words descending from Proto-Germanic ''*rīk-'' 'ruler, leader, king' and ''*hardu-'' 'strong, brave, hardy', and it therefore means 'strong in rule'. Nicknames include "Richie", "Dick", "Dickon", " Dickie", "Rich", "Rick", "Rico", "Ricky", and more. Richard is a common English, German and French male name. It's also used in many more languages, particularly Germanic, such as Norwegian, Danish, Swedish, Icelandic, and Dutch, as well as other languages including Irish, Scottish, Welsh and Finnish. Richard is cognate with variants of the name in other European languages, such as the Swedish "Rickard", the Catalan "Ricard" and the Italian "Riccardo", among others (see comprehensive variant list below). People named Richard Multiple people with the same name * Richard Andersen (other) * Richard Anderson (other) * Richard Cartwright (other) * Ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serge Abiteboul
Serge Joseph Abiteboul (born 25 August 1953 in Paris, France) is a French computer scientist working in the areas of data management, database theory, and finite model theory. Education The son of two hardware store owners, Abiteboul attended high-school in Romorantin, and Higher School Preparatory Classes in Tours. He was admitted to the Télécom Paris engineering school and studied at the Technion in Haifa for a year. Abiteboul received his PhD from the University of Southern California under the supervision of Seymour Ginsburg, in 1982. Career and research Abiteboul is a senior researcher at the Institut national de recherche en informatique et en automatique (INRIA), the French national research institute focussing on computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Donatello Santoro
Donato di Niccolò di Betto Bardi ( – 13 December 1466), better known as Donatello ( ), was a Florentine sculptor of the Renaissance period. Born in Florence, he studied classical sculpture and used this to develop a complete Renaissance style in sculpture. He spent time in other cities, and while there he worked on commissions and taught others; his periods in Rome, Padua, and Siena introduced to other parts of Italy his techniques, developed in the course of a long and productive career. Financed by Cosimo de' Medici, Donatello's ''David'' was the first freestanding nude male sculpture since antiquity. He worked with stone, bronze, wood, clay, stucco, and wax, and had several assistants, with four perhaps being a typical number. Although his best-known works mostly were statues in the round, he developed a new, very shallow, type of bas-relief for small works, and a good deal of his output was larger architectural reliefs. Early life Donatello was the son of Niccolò di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paolo Papotti
Paolo is both a given name and a surname, the Italian form of the name Paul. Notable people with the name include: People with the given name Paolo Art *Paolo Alboni (1671–1734), Italian painter *Paolo Abbate (1884–1973), Italian-American sculptor *Paolo Antonio Barbieri (1603–1649), Italian painter *Paolo Buggiani (born 1933), Italian contemporary artist *Paolo Carosone (born 1941), Italian painter and sculptor *Paolo Moranda Cavazzola (1486–1522), Italian painter *Paolo Farinati (c. 1524–c. 1606), Italian painter *Paolo Fiammingo (c. 1540–1596), Flemish painter *Paolo Domenico Finoglia (c. 1590–1645), Italian painter *Paolo Grilli (1857–1952), Italian sculptor and painter *Paolo de Matteis (1662–1728), Italian painter *Paolo Monaldi, Italian painter *Paolo Pagani (1655–1716), Italian painter *Paolo Persico (c. 1729–1796), Italian sculptor *Paolo Pino (1534–1565), Italian painter *Paolo Gerolamo Piola (1666–1724), Italian painter *Paolo Porpora (1617– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boris Motik
Boris may refer to: People * Boris (given name), a male given name *:''See'': List of people with given name Boris * Boris (surname) * Boris I of Bulgaria (died 907), the first Christian ruler of the First Bulgarian Empire, canonized after his death * Boris II of Bulgaria (c. 931–977), ruler of the First Bulgarian Empire * Boris III of Bulgaria (1894–1943), ruler of the Kingdom of Bulgaria in the first half of the 20th century * Boris, Prince of Tarnovo (born 1997), Spanish-born Bulgarian royal * Boris and Gleb (died 1015), the first saints canonized in Kievan Rus * Boris (singer) (born 1965), pseudonym of French singer Philippe Dhondt Arts and media * Boris (band), a Japanese experimental rock trio * ''Boris'' (EP), by Yezda Urfa, 1975 * "Boris" (song), by the Melvins, 1991 * ''Boris'' (TV series), a 2007–2009 Italian comedy series * '' Boris: The Film'', a 2011 Italian film based on the TV series * '' Boris: The Rise of Boris Johnson'', a 2006 biography by Andrew Gims ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
