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Linear Bounded Automaton
In computer science, a linear bounded automaton (plural linear bounded automata, abbreviated LBA) is a restricted form of Turing machine. Operation A linear bounded automaton is a nondeterministic Turing machine that satisfies the following three conditions: * Its input alphabet includes two special symbols, serving as left and right endmarkers. * Its transitions may not print other symbols over the endmarkers. * Its transitions may neither move to the left of the left endmarker nor to the right of the right endmarker. In other words: instead of having potentially infinite tape on which to compute, computation is restricted to the portion of the tape containing the input plus the two tape squares holding the endmarkers. An alternative, less restrictive definition is as follows: * Like a Turing machine, an LBA possesses a tape made up of cells that can contain symbols from a finite alphabet, a head that can read from or write to one cell on the tape at a time and can be moved, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, practical disciplines (including the design and implementation of Computer architecture, hardware and Computer programming, software). Computer science is generally considered an area of research, academic research and distinct from computer programming. 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 for preventing Vulnerability (computing), security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Myhill
John R. Myhill Sr. (11 August 1923 – 15 February 1987) was a British mathematician. Education Myhill received his Ph.D. from Harvard University under Willard Van Orman Quine in 1949. He was professor at SUNY Buffalo from 1966 until his death in 1987. He also taught at several other universities. His son, also called John Myhill, is a professor of linguistics in the English department of the University of Haifa in Israel. Contributions In the theory of formal languages, the Myhill–Nerode theorem, proven by Myhill with Anil Nerode, characterizes the regular languages as the languages that have only finitely many inequivalent prefixes. In computability theory, the Rice–Myhill–Shapiro theorem, more commonly known as Rice's theorem, states that, for any nontrivial property ''P'' of partial functions, it is undecidable to determine whether a given Turing machine computes a function with property ''P''. The Myhill isomorphism theorem is a computability-theoretic analogue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Savitch's Theorem
In computational complexity theory, Savitch's theorem, proved by Walter Savitch in 1970, gives a relationship between deterministic and non-deterministic space complexity. It states that for any function f\in\Omega(\log(n)), :\mathsf\left(f\left(n\right)\right) \subseteq \mathsf\left(f\left(n\right)^2\right). In other words, if a nondeterministic Turing machine can solve a problem using f(n) space, a deterministic Turing machine can solve the same problem in the square of that space bound.Arora & Barak (2009) p.86 Although it seems that nondeterminism may produce exponential gains in time (as formalized in the unproven exponential time hypothesis In computational complexity theory, the exponential time hypothesis is an unproven computational hardness assumption that was formulated by . It states that satisfiability of 3-CNF Boolean formulas cannot be solved more quickly than exponential t ...), Savitch's theorem shows that it has a markedly more limited effect on space requ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acta Informatica
''Acta Informatica'' is a Peer review, peer-reviewed scientific journal publishing original research papers in computer science. The journal is known mostly for publications in theoretical computer science. One of the two 1988 papers awarded the Gödel Prize in 1995 has appeared in this journal. The editor-in-chief is Christel Baier (Technische Universität Dresden). According to the ''Journal Citation Reports'', the journal had a 2020 impact factor of 0.375. References External links * Publications established in 1971 Springer Science+Business Media academic journals Computer science journals English-language journals Formal methods publications 8 times per year journals {{compu-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SIAM Journal On Computing
The ''SIAM Journal on Computing'' is a scientific journal focusing on the mathematical and formal aspects of computer science. It is published by the Society for Industrial and Applied Mathematics (SIAM). Although its official ISO abbreviation is ''SIAM J. Comput.'', its publisher and contributors frequently use the shorter abbreviation ''SICOMP''. SICOMP typically hosts the special issues of the IEEE Annual Symposium on Foundations of Computer Science (FOCS) and the Annual ACM Symposium on Theory of Computing (STOC), where about 15% of papers published in FOCS and STOC each year are invited to these special issues. For example, Volume 48 contains 11 out of 85 papers published in FOCS 2016. References * External linksSIAM Journal on Computing on |
Immerman–Szelepcsényi Theorem
In computational complexity theory, the Immerman–Szelepcsényi theorem states that nondeterministic space complexity classes are closed under complementation. It was proven independently by Neil Immerman and Róbert Szelepcsényi in 1987, for which they shared the 1995 Gödel Prize. In its general form the theorem states that NSPACE(''s''(''n'')) = co-NSPACE(''s''(''n'')) for any function ''s''(''n'') ≥ log ''n''. The result is equivalently stated as NL = co-NL; although this is the special case when ''s''(''n'') = log ''n'', it implies the general theorem by a standard padding argument. The result solved the second LBA problem. In other words, if a nondeterministic machine can solve a problem, another machine with the same resource bounds can solve its complement problem (with the ''yes'' and ''no'' answers reversed) in the same asymptotic amount of space. No similar result is known for the time complexity classes, and indeed it is conjectured that NP is not equal to c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DSPACE
DSpace is an open source repository software package typically used for creating open access repositories for scholarly and/or published digital content. While DSpace shares some feature overlap with content management systems and document management systems, the DSpace repository software serves a specific need as a digital archives system, focused on the long-term storage, access and preservation of digital content. The optional DSpace registry lists almost three thousand repositories all over the world. History The first public version of DSpace was released in November 2002, as a joint effort between developers from MIT and HP Labs. Following the first user group meeting in March 2004, a group of interested institutions formed the DSpace Federation, which determined the governance of future software development by adopting the Apache Foundation's community development model as well as establishing the DSpace Committer Group. In July 2007 as the DSpace user community grew larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NSPACE
In computational complexity theory, non-deterministic space or NSPACE is the computational resource describing the memory space for a non-deterministic Turing machine. It is the non-deterministic counterpart of DSPACE. Complexity classes The measure NSPACE is used to define the complexity class whose solutions can be determined by a non-deterministic Turing machine. The complexity class NSPACE(''f''(''n'')) is the set of decision problems that can be solved by a non-deterministic Turing machine, ''M'', using space ''O''(''f''(''n'')), where ''n'' is the length of the input. Several important complexity classes can be defined in terms of ''NSPACE''. These include: * REG = DSPACE(''O''(1)) = NSPACE(''O''(1)), where REG is the class of regular languages (nondeterminism does not add power in constant space). * NL = NSPACE(''O''(log ''n'')) * CSL = NSPACE(''O''(''n'')), where CSL is the class of context-sensitive languages. * PSPACE = NPSPACE = \bigcup_ \mathsf(n^k) * EXPSPACE ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Complexity Theory
In theoretical computer science and mathematics, computational complexity theory focuses on classifying computational problems according to their resource usage, and relating these classes to each other. A computational problem is a task solved by a computer. A computation problem is solvable by mechanical application of mathematical steps, such as an algorithm. A problem is regarded as inherently difficult if its solution requires significant resources, whatever the algorithm used. The theory formalizes this intuition, by introducing mathematical models of computation to study these problems and quantifying their computational complexity, i.e., the amount of resources needed to solve them, such as time and storage. Other measures of complexity are also used, such as the amount of communication (used in communication complexity), the number of gates in a circuit (used in circuit complexity) and the number of processors (used in parallel computing). One of the roles of computationa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Information And Control
''Information and Computation'' is a closed-access computer science journal published by Elsevier (formerly Academic Press). The journal was founded in 1957 under its former name ''Information and Control'' and given its current title in 1987. , the current editor-in-chief is David Peleg. The journal publishes 12 issues a year. History ''Information and Computation'' was founded as ''Information and Control'' in 1957 at the initiative of Leon Brillouin and under the editorship of Leon Brillouin, Colin Cherry and Peter Elias. Murray Eden joined as editor in 1962 and became sole editor-in-chief in 1967. He was succeeded by Albert R. Meyer in 1981, under whose editorship the journal was rebranded ''Information and Computation'' in 1987 in response to the shifted focus of the journal towards theory of computation and away from control theory. In 2020, Albert Mayer was succeeded by David Peleg as editor-in-chief of the journal. Indexing All articles from the ''Information and Comput ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Landweber
Peter Steven Landweber (born August 17, 1940, in Washington D. C.) is an American mathematician working in algebraic topology. Landweber studied at the University of Iowa (B.SC. 1960) and the Harvard University (master's degree 1961), where he graduated in 1965 after studying under Raoul Bott (Künneth formulas for bordism theories). He was then Assistant Professor at the University of Virginia (from 1965) and at Yale University from 1968 to 1970. From 1967 to 1968 he was at the Institute for Advanced Study in Princeton, New Jersey. In 1970, he became Associate Professor at the Rutgers University, where he taught from 1974 until his retirement in 2007. From 1974 to 1975 he was a NATO fellow at the University of Cambridge. Since 2007, he is a Professor Emeritus at Rutgers University. Landweber studied complex bordism in algebraic topology (introducing Landweber–Novikov algebra in the 1960s). In the beginning of the 1970s, he proved his exact functor theorem, which allows the con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sentential Form
In formal language theory, a grammar (when the context is not given, often called a formal grammar for clarity) describes how to form strings from a language's alphabet that are valid according to the language's syntax. A grammar does not describe the meaning of the strings or what can be done with them in whatever context—only their form. A formal grammar is defined as a set of production rules for such strings in a formal language. Formal language theory, the discipline that studies formal grammars and languages, is a branch of applied mathematics. Its applications are found in theoretical computer science, theoretical linguistics, formal semantics, mathematical logic, and other areas. A formal grammar is a set of rules for rewriting strings, along with a "start symbol" from which rewriting starts. Therefore, a grammar is usually thought of as a language generator. However, it can also sometimes be used as the basis for a "recognizer"—a function in computing that deter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
