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Stream X-Machine
The Stream X-machine (SXM) is a model of computation introduced by Gilbert Laycock in his 1993 PhD thesis, ''The Theory and Practice of Specification Based Software Testing''.Gilbert Laycock (1993) ''The Theory and Practice of Specification Based Software Testing''. PhD Thesis, University of Sheffield, Dept of Computer Science. {{Webarchive, url=https://web.archive.org/web/20071105145328/http://www.mcs.le.ac.uk/people/gtl1/PhDabstract.html , date=2007-11-05 Based on Samuel Eilenberg's X-machine, an extended finite-state machine for processing data of the type ''X'',Samuel Eilenberg (1974) ''Automata, Languages and Machines, Vol. A''. London: Academic Press. the Stream X-Machine is a kind of X-machine for processing a memory data type ''Mem'' with associated input and output streams ''In''* and ''Out''*, that is, where ''X'' = ''Out''* × ''Mem'' × ''In''*. The transitions of a Stream X-Machine are labelled by functions of the form φ: ''Mem'' × ''In'' → ''Out'' × ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Eilenberg
Samuel Eilenberg (September 30, 1913 – January 30, 1998) was a Polish-American mathematician who co-founded category theory (with Saunders Mac Lane) and homological algebra. Early life and education He was born in Warsaw, Kingdom of Poland to a Jewish family. He spent much of his career as a professor at Columbia University. He earned his Ph.D. from University of Warsaw in 1936, with thesis ''On the Topological Applications of Maps onto a Circle''; his thesis advisors were Kazimierz Kuratowski and Karol Borsuk. He died in New York City in January 1998. Career Eilenberg's main body of work was in algebraic topology. He worked on the axiomatic treatment of homology theory with Norman Steenrod (and the Eilenberg–Steenrod axioms are named for the pair), and on homological algebra with Saunders Mac Lane. In the process, Eilenberg and Mac Lane created category theory. Eilenberg was a member of Bourbaki and, with Henri Cartan, wrote the 1956 book ''Homological Algebra''. Later ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-machine
The X-machine (''XM'') is a theoretical model of computation introduced by Samuel Eilenberg in 1974.S. Eilenberg (1974) ''Automata, Languages and Machines, Vol. A''. Academic Press, London. The ''X'' in "X-machine" represents the fundamental data type on which the machine operates; for example, a machine that operates on databases (objects of type ''database'') would be a ''database''-machine. The X-machine model is structurally the same as the finite-state machine, except that the symbols used to label the machine's transitions denote relations of type ''X''→''X''. Crossing a transition is equivalent to applying the relation that labels it (computing a set of changes to the data type ''X''), and traversing a path in the machine corresponds to applying all the associated relations, one after the other. Original theory Eilenberg's original X-machine was a completely general theoretical model of computation (subsuming the Turing machine, for example), which admitted determi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finite-state Machine
A finite-state machine (FSM) or finite-state automaton (FSA, plural: ''automata''), finite automaton, or simply a state machine, is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number of '' states'' at any given time. The FSM can change from one state to another in response to some inputs; the change from one state to another is called a ''transition''. An FSM is defined by a list of its states, its initial state, and the inputs that trigger each transition. Finite-state machines are of two types— deterministic finite-state machines and non-deterministic finite-state machines. A deterministic finite-state machine can be constructed equivalent to any non-deterministic one. The behavior of state machines can be observed in many devices in modern society that perform a predetermined sequence of actions depending on a sequence of events with which they are presented. Simple examples are vending machines, which dispense p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Functional Testing
Functional testing is a quality assurance (QA) processPrasad, Dr. K.V.K.K. (2008) ''ISTQB Certification Study Guide'', Wiley, , p. vi and a type of black-box testing that bases its test cases on the specifications of the software component under test. Functions are tested by feeding them input and examining the output, and internal program structure is rarely considered (unlike white-box testing).Kaner, Falk, Nguyen. ''Testing Computer Software''. Wiley Computer Publishing, 1999, p. 42. . Functional testing is conducted to evaluate the compliance of a system or component with specified functional requirements. Functional testing usually describes ''what'' the system does. Since functional testing is a type of black-box testing, the software's functionality can be tested without knowing the internal workings of the software. This means that testers do not need to know programming languages or how the software has been implemented. This, in turn, could lead to reduced developer bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Biology
Computational biology refers to the use of data analysis, mathematical modeling and computational simulations to understand biological systems and relationships. An intersection of computer science, biology, and big data, the field also has foundations in applied mathematics, chemistry, and genetics. It differs from biological computing, a subfield of computer engineering which uses bioengineering to build computers. History Bioinformatics, the analysis of informatics processes in biological systems, began in the early 1970s. At this time, research in artificial intelligence was using network models of the human brain in order to generate new algorithms. This use of biological data pushed biological researchers to use computers to evaluate and compare large data sets in their own field. By 1982, researchers shared information via punch cards. The amount of data grew exponentially by the end of the 1980s, requiring new computational methods for quickly interpreting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Testing
Software testing is the act of examining the artifacts and the behavior of the software under test by validation and verification. Software testing can also provide an objective, independent view of the software to allow the business to appreciate and understand the risks of software implementation. Test techniques include, but not necessarily limited to: * analyzing the product requirements for completeness and correctness in various contexts like industry perspective, business perspective, feasibility and viability of implementation, usability, performance, security, infrastructure considerations, etc. * reviewing the product architecture and the overall design of the product * working with product developers on improvement in coding techniques, design patterns, tests that can be written as part of code based on various techniques like boundary conditions, etc. * executing a program or application with the intent of examining behavior * reviewing the deployment infrastructure a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Economics
Computational Economics is an interdisciplinary research discipline that involves computer science, economics, and management science.''Computational Economics''."About This Journal"an"Aims and Scope" This subject encompasses computational modeling of economic systems. Some of these areas are unique, while others established areas of economics by allowing robust data analytics and solutions of problems that would be arduous to research without computers and associated numerical methods.• Hans M. Amman, David A. Kendrick, and John Rust, ed., 1996. ''Handbook of Computational Economics'', v. 1, ElsevierDescription & chapter-previelinks. • Kenneth L. Judd, 1998. ''Numerical Methods in Economics'', MIT Press. Links tdescription anchapter previews Computational methods have been applied in various fields of economics research, including but not limiting to: Econometrics: Non-parametric approaches, Semi-parametric approaches, and Machine Learning. Dynamic Syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-Machine Testing
The (Stream) X-Machine Testing Methodology is a ''complete'' functional testing approach to software- and hardware testingM. Holcombe and F. Ipate (1998) ''Correct Systems - Building a Business Process Solution''. Springer, Applied Computing Series. that exploits the scalability of the Stream X-Machine model of computation.Gilbert Laycock (1993) ''The Theory and Practice of Specification Based Software Testing''. PhD Thesis, University of SheffieldAbstract Using this methodology, it is likely to identify a finite test-set that exhaustively determines whether the tested system's implementation matches its specification. This goal is achieved by a divide-and-conquer approach, in which the design is decomposed by refinementF. Ipate and M. Holcombe (1998) 'A method for refining and testing generalised machine specifications'. ''Int. J. Comp. Math.'' 68, pp. 197–219. into a collection of Stream X-Machines, which are implemented as separate modules, then tested bottom-up. At each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communicating X-Machine
The Communicating (Stream) X-Machine is a model of computation introduced by various researchers in the 1990s to model systems composed of communicating agents. The model exists in several variants, which are either based directly on Samuel Eilenberg's X-machineS. Eilenberg (1974) ''Automata, Languages and Machines, Vol. A''. Academic Press, London. or on Gilbert Laycock's later Stream X-Machine The Stream X-machine (SXM) is a model of computation introduced by Gilbert Laycock in his 1993 PhD thesis, ''The Theory and Practice of Specification Based Software Testing''.Gilbert Laycock (1993) ''The Theory and Practice of Specification Based ....Gilbert Laycock (1993) ''The Theory and Practice of Specification Based Software Testing''. PhD Thesis, University of Sheffield. Abstract{{Webarchive, url=https://web.archive.org/web/20071105145328/http://www.mcs.le.ac.uk/people/gtl1/PhDabstract.html , date=2007-11-05 References Theory of computation Models of computation< ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sheffield University
, mottoeng = To discover the causes of things , established = – University of SheffieldPredecessor institutions: – Sheffield Medical School – Firth College – Sheffield Technical School – University College of Sheffield , type = Public research university , academic_staff = 5,670 (2020) - including academic atypical staff , administrative_staff = , chancellor = Lady Justice Rafferty , vice_chancellor = Koen Lamberts , students = () , undergrad = () , postgrad = () , endowment = £46.7 million (2021) , budget = £741.0 million (2020–21) , city = Sheffield , state = South Yorkshire , country = England , coor = , campus = Urban , colours = Black & gold , affiliations = Russell Group WUN ACUN8 Group White Rose Sutton 30EQUISAMBAUniversities UK , website = , logo = The University of Sheffield (informally Sheffield University or TUOS) is a public research university in Sheffield, South Yorkshire, England. Its history traces back to the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theory Of Computation
In theoretical computer science and mathematics, the theory of computation is the branch that deals with what problems can be solved on a model of computation, using an algorithm, how efficiently they can be solved or to what degree (e.g., approximate solutions versus precise ones). The field is divided into three major branches: automata theory and formal languages, computability theory, and computational complexity theory, which are linked by the question: ''"What are the fundamental capabilities and limitations of computers?".'' In order to perform a rigorous study of computation, computer scientists work with a mathematical abstraction of computers called a model of computation. There are several models in use, but the most commonly examined is the Turing machine. Computer scientists study the Turing machine because it is simple to formulate, can be analyzed and used to prove results, and because it represents what many consider the most powerful possible "reasonable" mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Models Of Computation
In computer science, and more specifically in computability theory and computational complexity theory, a model of computation is a model which describes how an output of a mathematical function is computed given an input. A model describes how units of computations, memories, and communications are organized. The computational complexity of an algorithm can be measured given a model of computation. Using a model allows studying the performance of algorithms independently of the variations that are specific to particular implementations and specific technology. Models Models of computation can be classified into three categories: sequential models, functional models, and concurrent models. Sequential models Sequential models include: * Finite state machines * Post machines (Post–Turing machines and tag machines). * Pushdown automata * Register machines ** Random-access machines * Turing machines * Decision tree model Functional models Functional models include: * Abstract rew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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