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Lehman's Laws Of Software Evolution
In software engineering, the laws of software evolution refer to a series of laws that Lehman and Belady formulated starting in 1974 with respect to software evolution. The laws describe a balance between forces driving new developments on one hand, and forces that slow down progress on the other hand. Over the past decades the laws have been revised and extended several times.Liguo Yu and Alok Mishra (2013) An Empirical Study of Lehman’s Law on Software Quality Evolution in International Journal of Software and Informatics, 11/2013; 7(3):469-481. Context Observing that most software is subject to change in the course of its existence, the authors set out to determine laws that these changes will typically obey, or must obey for the software to survive. In his 1980 article, Lehman qualified the application of such laws by distinguishing between three categories of software: * An ''S''-program is written according to an exact ''specification'' of what that program can do. For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Engineering
Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principles and computer programming expertise to develop software systems that meet user needs. The terms ''programmer'' and ''coder'' overlap ''software engineer'', but they imply only the construction aspect of a typical software engineer workload. A software engineer applies a software development process, which involves defining, Implementation, implementing, Software testing, testing, Project management, managing, and Software maintenance, maintaining software systems, as well as developing the software development process itself. History Beginning in the 1960s, software engineering was recognized as a separate field of engineering. The development of software engineering was seen as a struggle. Problems included software that was over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meir Manny Lehman
Meir "Manny" Lehman, FREng (24 January 1925 – 29 December 2010) was a professor in the School of Computing Science at Middlesex University. From 1972 to 2002 he was a Professor and Head of the Computing Department at Imperial College London. His research contributions include the early realisation of the software evolution phenomenon and the eponymous Lehman's laws of software evolution. Career Lehman was born in Germany on 24 January 1925 and emigrated to England in 1931. He studied mathematics as an undergraduate at Imperial College London where he was involved in the design of the Imperial College Computing Engine's Digital Computer Arithmetic Unit. He spent a year at Ferranti in London before working at Israel's Ministry of Defense from 1957 to 1964. From 1964 to 1972 he worked at IBM's research division in Yorktown Heights, NY where he studied program evolution with Les Belady. The study of IBM's programming process gave the foundations for Lehman's laws of software evo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Evolution
Software evolution is the continual development of a piece of software after its initial release to address changing stakeholder and/or market requirements. Software evolution is important because organizations invest large amounts of money in their software and are completely dependent on this software. Software evolution helps software adapt to changing businesses requirements, fix defects, and integrate with other changing systems in a software system environment. General introduction Fred Brooks, in his key book ''The Mythical Man-Month'', states that over 90% of the costs of a typical system arise in the maintenance phase, and that any successful piece of software will inevitably be maintained. In fact, Agile methods stem from maintenance-like activities in and around web based technologies, where the bulk of the capability comes from frameworks and standards. Software maintenance addresses bug fixes and minor enhancements, while software evolution focuses on adaptation and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eight Queens Puzzle
The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens threaten each other; thus, a solution requires that no two queens share the same row, column, or diagonal. There are 92 solutions. The problem was first posed in the mid-19th century. In the modern era, it is often used as an example problem for various computer programming techniques. The eight queens puzzle is a special case of the more general ''n'' queens problem of placing ''n'' non-attacking queens on an ''n''×''n'' chessboard. Solutions exist for all natural numbers ''n'' with the exception of ''n'' = 2 and ''n'' = 3. Although the exact number of solutions is only known for ''n'' ≤ 27, the asymptotic growth rate of the number of solutions is approximately (0.143 ''n'')''n''. History Chess composer Max Bezzel published the eight queens puzzle in 1848. Franz Nauck published the first solutions in 1850. W. W. Rouse Ball (1960) "The Eight Queens Problem" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invariant Work Rate
Invariant and invariance may refer to: Computer science * Invariant (computer science), an expression whose value doesn't change during program execution ** Loop invariant, a property of a program loop that is true before (and after) each iteration * A data type in method overriding that is neither covariant nor contravariant * Class invariant, an invariant used to constrain objects of a class Physics, mathematics, and statistics * Invariant (mathematics), a property of a mathematical object that is not changed by a specific operation or transformation ** Rotational invariance, the property of function whose value does not change when arbitrary rotations are applied to its argument ** Scale invariance, a property of objects or laws that do not change if scales of length, energy, or other variables, are multiplied by a common factor ** Topological invariant * Invariant (physics), something does not change under a transformation, such as from one reference frame to another * Invaria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incremental Growth
Increment or incremental may refer to: *Incrementalism, a theory (also used in politics as a synonym for gradualism) *Increment and decrement operators, the operators ++ and -- in computer programming *Incremental computing *Incremental backup, which contain only that portion that has changed since the preceding backup copy. *Increment, chess term for additional time a chess player receives on each move *Incremental games * Increment in rounding See also * * *1+1 (other) *++ (other) ++ may refer to: * Checkmate, in chess notation * The increment operator, in some programming languages * ''Much higher than normal'', in some medical tests * ''+ +'' (EP), by South Korean girl group Loona See also * PLUSPLUS, a Ukrainian TV ch ... {{Disambiguation da:Inkrementel fr:Incrémentation nl:Increment ja:インクリメント pl:Inkrementacja ru:Инкремент sr:Инкремент sv:++ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
