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Actor Model (computer Science)
The actor model in computer science is a mathematical model of concurrent computation that treats ''actor'' as the universal primitive of concurrent computation. In response to a message it receives, an actor can: make local decisions, create more actors, send more messages, and determine how to respond to the next message received. Actors may modify their own private state, but can only affect each other indirectly through messaging (removing the need for lock-based synchronization). The actor model originated in 1973. It has been used both as a framework for a theoretical understanding of computation and as the theoretical basis for several practical implementations of concurrent systems. The relationship of the model to other work is discussed in actor model and process calculi. History According to Carl Hewitt, unlike previous models of computation, the actor model was inspired by physics, including general relativity and quantum mechanics. It was also influenced by the ... [...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] |
Capability-based Security
Capability-based security is a concept in the design of secure computing systems, one of the existing security models. A capability (known in some systems as a key) is a communicable, unforgeable token of authority. It refers to a value that references an object along with an associated set of access rights. A user program on a capability-based operating system must use a capability to access an object. Capability-based security refers to the principle of designing user programs such that they directly share capabilities with each other according to the principle of least privilege, and to the operating system infrastructure necessary to make such transactions efficient and secure. Capability-based security is to be contrasted with an approach that uses traditional UNIX permissions and Access Control Lists. Although most operating systems implement a facility which resembles capabilities, they typically do not provide enough support to allow for the exchange of capabilities amo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California Institute Of Technology
The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasionally referred to as "CIT", most notably in its alma mater, but this is uncommon. is a private research university in Pasadena, California. Caltech is ranked among the best and most selective academic institutions in the world, and with an enrollment of approximately 2400 students (acceptance rate of only 5.7%), it is one of the world's most selective universities. The university is known for its strength in science and engineering, and is among a small group of institutes of technology in the United States which is primarily devoted to the instruction of pure and applied sciences. The institution was founded as a preparatory and vocational school by Amos G. Throop in 1891 and began attracting influential scientists such as George Ellery H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Massachusetts Institute Of Technology
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the most prestigious and highly ranked academic institutions in the world. Founded in response to the increasing industrialization of the United States, MIT adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. MIT is one of three private land grant universities in the United States, the others being Cornell University and Tuskegee University. The institute has an urban campus that extends more than a mile (1.6 km) alongside the Charles River, and encompasses a number of major off-campus facilities such as the MIT Lincoln Laboratory, the Bates Center, and the Haystack Observatory, as well as affiliated laboratories such as the Broad and Whitehead Institutes. , 98 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actor Model Theory
In theoretical computer science, Actor model theory concerns theoretical issues for the Actor model. Actors are the primitives that form the basis of the Actor model of concurrent digital computation. In response to a message that it receives, an Actor can make local decisions, create more Actors, send more messages, and designate how to respond to the next message received. Actor model theory incorporates theories of the events and structures of Actor computations, their proof theory, and denotational models. Events and their orderings From the definition of an Actor, it can be seen that numerous events take place: local decisions, creating Actors, sending messages, receiving messages, and designating how to respond to the next message received. However, this article focuses on just those events that are the arrival of a message sent to an Actor. This article reports on the results published in Hewitt 006 :''Law of Countability'': There are at most countably many events. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gul Agha (computer Scientist)
Gul Agha (گُل آغا) is a professor of computer science at the University of Illinois at Urbana-Champaign, and director of the Open Systems Laboratory. He is known for his work on the actor model of concurrent computing, concurrent computation, and was also Editor-in-Chief of ''ACM Computing Surveys'' from 1999 to 2007. Agha was born and completed his early schooling in Sindh, Pakistan. Agha completed his B.S. with honors at the California Institute of Technology in the year 1977.Dunya, S. Gul Agha: The Talented Computer Scientist of Sindh. Feb 26, 2016. Sindhi Dunya: Voice of Sindh Culture. Accessed September 20, 2017 He received his Doctor of Philosophy, Ph. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Domains
In denotational semantics and domain theory, power domains are domains of nondeterministic and concurrent computations. The idea of power domains for functions is that a nondeterministic function may be described as a deterministic set-valued function, where the set contains all values the nondeterministic function can take for a given argument. For concurrent systems, the idea is to express the set of all possible computations. Roughly speaking, a power domain is a domain whose elements are certain subsets of a domain. Taking this approach naively, though, often gives rise to domains that don't quite have the desired properties, and so one is led to increasingly complicated notions of power domain. There are three common variants: the Plotkin, upper, and lower power domains. One way to understand these concepts is as free models of theories of nondeterminism. For most of this article we use the terms "domain" and "continuous function" quite loosely, meaning respectively some k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Clinger (computer Scientist)
William D. Clinger is an associate professor in the Khoury College of Computer Sciences at Northeastern University. He is known for his work on higher-order and functional programming languages, and for extensive contributions in helping create and implement international technical standards for the programming language Scheme via the Institute of Electrical and Electronics Engineers (IEEE) and American National Standards Institute (ANSI). Clinger was an editor of the second through fifth Revised Reports on Scheme (R2RS – R5RS), and an invited speaker on Scheme at the Lisp50 conference celebrating the 50th birthday of the language Lisp. He has been on the faculty at Northeastern University since 1994. Research Clinger obtained his PhD from the Massachusetts Institute of Technology (MIT) under the supervision of Carl Hewitt. His doctoral research revolved around defining a denotational semantics for the actor model of concurrent computing, which is the same model of computing that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry Baker (computer Scientist)
Henry Givens Baker Jr. is an American computer scientist who has made contributions in garbage collection, functional programming languages, and linear logic. He was one of the founders of Symbolics, a company that designed and manufactured a line of Lisp machines. In 2006 he was recognized as a Distinguished Scientist by the Association for Computing Machinery. He is notable for his research in garbage collection, particularly Baker's real-time copying collector, and on the Actor model. Baker received his B.Sc. (1969), S.M. (1973), E.E. (1973), and Ph.D. (1978) degrees at M.I.T. The Chicken Scheme compiler Chicken (stylized as CHICKEN) is a programming language, specifically a compiler and interpreter which implement a dialect of the programming language Scheme, and which compiles Scheme source code to standard C. It is mostly R5RS compliant an ... was inspired by an innovative design of Baker's. Bibliography * * * * * References External links Henry Baker's Archive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operational Semantics
Operational semantics is a category of formal programming language semantics in which certain desired properties of a program, such as correctness, safety or security, are verified by constructing proofs from logical statements about its execution and procedures, rather than by attaching mathematical meanings to its terms (denotational semantics). Operational semantics are classified in two categories: structural operational semantics (or small-step semantics) formally describe how the ''individual steps'' of a computation take place in a computer-based system; by opposition natural semantics (or big-step semantics) describe how the ''overall results'' of the executions are obtained. Other approaches to providing a formal semantics of programming languages include axiomatic semantics and denotational semantics. The operational semantics for a programming language describes how a valid program is interpreted as sequences of computational steps. These sequences then ''are'' the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irene Greif
Irene Greif is an American computer scientist and a founder of the field of computer-supported cooperative work (CSCW). She was the first woman to earn a Ph.D. in computer science from the Massachusetts Institute of Technology. Biography Greif's mother was an accountant, and a native of New York City. Greif has at least one sibling, a sister. She attended Hunter College High School before earning her undergraduate and graduate degrees from MIT. In 1975, Greif became the first woman to earn a Ph.D. in computer science from MIT; in her dissertation of that year, she published the first operational actor model. She was a professor of computer science at the University of Washington before returning to MIT as a professor of electrical engineering and computer science (1977–87). In 1984, Greif and Paul Cashman coined the term "Computer Supported Cooperative Work" and the initials, CSCW, at an interdisciplinary workshop in Cambridge, Massachusetts. Preferring research over teachi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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