Actor model

In computer science, the Actor model, first published in 1973 (Hewitt et al. 1973), is a mathematical model of concurrent computation. The Actor model treats “Actors” as the universal primitives 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 determine how to respond to the next message received. The Actor model has been used both as a framework within which to develop a theor ...

Including:

• Actor model - History
• Actor model - Fundamental concepts
• Actor model - Formal systems
• Actor model - Applications
• Actor model - Models prior to the Actor model
• Actor model - Lambda calculus
• Actor model - Simula
• Actor model - Smalltalk
• Actor model - Petri nets
• Actor model - Message Passing Semantics
• Actor model - The unbounded nondeterminism controversy
• Actor model - Direct communication and asynchrony
• Actor model - Actor creation plus addresses in messages means variable topology
• Actor model - Inherently concurrent
• Actor model - No requirement on order of message arrival
• Actor model - Not sequentiality not buffering not synchrony and not fixed topology
• Actor model - Locality
• Actor model - Compositionality
• Actor model - Behaviors
• Actor model - Relationship to mathematical logic
• Actor model - Migration
• Actor model - Security
• Actor model - Synthesizing addresses of Actors
• Actor model - Why is the Actor model important now?
• Actor model - Actor researchers

Read more here: » Actor model: Encyclopedia - Actor model

The Actor model is about the semantics of message passing. Actor model - The unbounded nondeterminism controversy. Arguably, the first concurrent programs were interrupt handlers. During the course of its normal operation, a computer needed to be able to receive information from outside (characters from a keyboard, packets from a network, etc.). So when the information arrived execution of the computer was "interrupted" and special code called an interrupt handler was called to put the information in a b ...

See also:

Actor model, Actor model - History, Actor model - Fundamental concepts, Actor model - Formal systems, Actor model - Applications, Actor model - Models prior to the Actor model, Actor model - Lambda calculus, Actor model - Simula, Actor model - Smalltalk, Actor model - Petri nets, Actor model - Message Passing Semantics, Actor model - The unbounded nondeterminism controversy, Actor model - Direct communication and asynchrony, Actor model - Actor creation plus addresses in messages means variable topology, Actor model - Inherently concurrent, Actor model - No requirement on order of message arrival, Actor model - Not sequentiality not buffering not synchrony and not fixed topology, Actor model - Locality, Actor model - Compositionality, Actor model - Behaviors, Actor model - Relationship to mathematical logic, Actor model - Migration, Actor model - Security, Actor model - Synthesizing addresses of Actors, Actor model - Why is the Actor model important now?, Actor model - Actor researchers

Read more here: » Actor model: Encyclopedia II - Actor model - Message Passing Semantics

In Object-Oriented Programming (OOP), an instance of a program (i.e. a program running in a computer) is treated as a dynamic set of interacting objects. Objects in OOP extend the more general notion of objects described above to include a very specific kind of typing, which among other things allows for: data members that represent the data associated with the object. methods that access the data members in predefined ways. In the case of most objects, one can access the data members only through the meth ...

See also:

Object computer science, Object computer science - Objects in Object-Oriented Programming

Read more here: » Object computer science: Encyclopedia II - Object computer science - Objects in Object-Oriented Programming

Ether systems have characteristics of monotonicity, concurrency, commutativity, and pluralism. monotonicity: Once something is published it cannot be withdrawn. Scientists publish their results so they are available to all. Published work is collected and indexed in libraries. Scientists who change their mind can publish later articles contradicting earlier ones. However, they are not allowed to go into the libraries and "erase" old publications. concurrency: Scientis ...

See also:

Scientific Community Metaphor, Scientific Community Metaphor - Monotonicity Concurrency Commutatvity and Pluralism, Scientific Community Metaphor - Proposing Modifying Supporting and Opposing, Scientific Community Metaphor - Viewpoints Inheritance Translation and Negotiation, Scientific Community Metaphor - Emphasis on communities rather than individuals, Scientific Community Metaphor - Why is the Scientific Community Metaphor important now?, Scientific Community Metaphor - Reference

Read more here: » Scientific Community Metaphor: Encyclopedia II - Scientific Community Metaphor - Monotonicity Concurrency Commutatvity and Pluralism

All completeness properties are described along a similar scheme: one describes a certain class of subsets of a partial order that are required to have a supremum or infimum. Hence every completeness property has its dual, obtained by inverting the order-dependent definitions in the given statement. Some of the notions are usually not dualized while others may be self-dual (i.e. equivalent to their dual statements). ...

See also:

Completeness order theory, Completeness order theory - Types of completeness properties, Completeness order theory - Least and greatest elements, Completeness order theory - Finite completeness, Completeness order theory - Further completeness conditions, Completeness order theory - Relationships between completeness properties, Completeness order theory - Completions of domains, Completeness order theory - Completeness in terms of universal algebra, Completeness order theory - Completeness in terms of adjunctions, Completeness order theory - Notes, Completeness order theory - Reference

Read more here: » Completeness order theory: Encyclopedia II - Completeness order theory - Types of completeness properties

An asynchronous circuit is a circuit in which the parts are largely autonomous. They are not governed by a clock circuit or global clock signal, but instead need only wait for the signals that indicate completion of instructions and operations. These signals are specified by simple data transfer protocols. This digital logic design is contrasted with a synchronous circuit which operates according to clock timing signals. Asynchronous circuit - Benefits. Different classes of asynchronous circuitry offer diff ...

Including:

• Asynchronous circuit - Benefits
• Asynchronous circuit - Applications
• Asynchronous circuit - Theoretical Foundations
• Asynchronous circuit - Quotes

Read more here: » Asynchronous circuit: Encyclopedia - Asynchronous circuit

In programming languages, a closure is an abstraction that combines a function and a special lexical environment bound to that function (scope). The variables in the lexical environment are designed to retain state information between function calls. Unlike garden-variety functions which retain no memory of what happened in previous calls, closures are capable of storing information across function calls. Closure lexical variables differ from global variables in that they do not occupy (or pollute) the global variable ...

Including:

• Closure computer science - Implementation and theory
• Closure computer science - Closures and functions
• Closure computer science - Uses of closures
• Closure computer science - Programming languages with closures
• Closure computer science - Simulating closures
• Closure computer science - Reference

Read more here: » Closure computer science: Encyclopedia - Closure computer science

Scientific research includes generating theories and processes for modifying, supporting, and opposing these theories. Karl Popper called the process "conjectures and refutations", which although expressing a core insight, has been shown to be too restrictive a characterization by the work of Michel Callon, Paul Feyerabend, Elihu M. Gerson, Mark Johnson, Thomas Kuhn, George Lakoff, Imre Lakatos, Bruno Latour, John Law, Susan Leigh Star, Anslem Strauss, Lucy Suchman, Ludwig Wittgenstein, etc.. Three basic kinds of participation in Ether are proposing, supporting, and o ...

See also:

Scientific Community Metaphor, Scientific Community Metaphor - Monotonicity Concurrency Commutatvity and Pluralism, Scientific Community Metaphor - Proposing Modifying Supporting and Opposing, Scientific Community Metaphor - Viewpoints Inheritance Translation and Negotiation, Scientific Community Metaphor - Emphasis on communities rather than individuals, Scientific Community Metaphor - Why is the Scientific Community Metaphor important now?, Scientific Community Metaphor - Reference

Read more here: » Scientific Community Metaphor: Encyclopedia II - Scientific Community Metaphor - Proposing Modifying Supporting and Opposing

Concurrent programming languages are programming languages that use language constructs for concurrency. These constructs may involve multi-threading, support for distributed computing, message passing, shared resources (including shared memory) or futures (known also as promises). In some languages communication between concurrent parts of an application is hidden from the programmer (e.g., by using futures), while in others it must be handled explicitly. Explicit communication can be divided into two classes: ...

Including:

• Concurrent programming language - Languages where concurrency is important

Read more here: » Concurrent programming language: Encyclopedia - Concurrent programming language

Developments in hardware and software technology for the Internet since the original paper was published have tended to increase the importance of the Scientific Community Metaphor. Legal concerns (e.g., HIPAA, Sarbanes-Oxley , "The Books and Records Rules" in SEC Rule 17a-3/4 and "Design Criteria Standard for Electronic Records Management Software Applications" in DOD 5015.2 in the US) are leading organizations to store information monotonically forever. It has just now become less costly in many cases to store information on ...

See also:

Scientific Community Metaphor, Scientific Community Metaphor - Monotonicity Concurrency Commutatvity and Pluralism, Scientific Community Metaphor - Proposing Modifying Supporting and Opposing, Scientific Community Metaphor - Viewpoints Inheritance Translation and Negotiation, Scientific Community Metaphor - Emphasis on communities rather than individuals, Scientific Community Metaphor - Why is the Scientific Community Metaphor important now?, Scientific Community Metaphor - Reference

Read more here: » Scientific Community Metaphor: Encyclopedia II - Scientific Community Metaphor - Why is the Scientific Community Metaphor important now?

Alan Turing was one of the first to attempt to more precisely characterize individual intelligence through the notion of his famous Turing Test. This paradigm was developed and deepened in the field of Artificial Intelligence. Allen Newell and Herbert Simon did pioneer work in analyzing the protocols of individual human problem solving behavior on puzzles. More recently Marvin Minsky has developed the idea that the mind of an individual human is composed of a society of agents in Society of Mind (see the analysis by Push Singh). The above research ...

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Scientific Community Metaphor, Scientific Community Metaphor - Monotonicity Concurrency Commutatvity and Pluralism, Scientific Community Metaphor - Proposing Modifying Supporting and Opposing, Scientific Community Metaphor - Viewpoints Inheritance Translation and Negotiation, Scientific Community Metaphor - Emphasis on communities rather than individuals, Scientific Community Metaphor - Why is the Scientific Community Metaphor important now?, Scientific Community Metaphor - Reference

Read more here: » Scientific Community Metaphor: Encyclopedia II - Scientific Community Metaphor - Emphasis on communities rather than individuals

Message in its most general meaning is the object of communication. Depending on the context, the term may apply to both the information contents and its actual presentation. In the communications discipline, a message is information which is sent from a source to a receiver. Some common definitions include: Any thought or idea expressed briefly in a plain or secret language, prepared in a form suitable for transmission by any means of communication. An arbitrary amount of information whose beginnin ...

Including:

• Message - History of messaging

Read more here: » Message: Encyclopedia - Message

In computer networking and telecommunications, packet switching is the now-dominant communications paradigm, in which packets (units of information carriage) are individually routed between nodes over data links which might be shared by many other nodes. This contrasts with the principal other paradigm, circuit switching, which sets up a dedicated connection between the two nodes for their exclusive use for the duration of the communication. Packet switching is used to optimize the use of the bandwidth available in a network, to minimize the transmission latency (i.e. the time it takes for data to pass across the ...

Including:

• Packet switching - Packets
• Packet switching - Packet routing
• Packet switching - Packet switching in the Internet
• Packet switching - Controversy over invention of packet switching
• Packet switching - Work at MIT
• Packet switching - Work at RAND
• Packet switching - Work at National Physical Laboratory
• Packet switching - Simultaneous Development
• Packet switching - Reference

Read more here: » Packet switching: Encyclopedia - Packet switching

In the mathematical area of order theory, completeness properties assert the existence of certain infima or suprema of a given partially ordered set. A special use of the term refers to complete partial orders or complete lattices. However, many other interesting notions of completeness exist. The motivation for considering completeness properties derives from the great importance of suprema (least upper bounds, joins, "") and infima (greatest lower bounds, meets, "") to the theory of partial orders. Finding a supremum means to ...

Including:

• Completeness order theory - Types of completeness properties
• Completeness order theory - Least and greatest elements
• Completeness order theory - Finite completeness
• Completeness order theory - Further completeness conditions
• Completeness order theory - Relationships between completeness properties
• Completeness order theory - Completions of domains
• Completeness order theory - Completeness in terms of universal algebra
• Completeness order theory - Completeness in terms of adjunctions
• Completeness order theory - Notes
• Completeness order theory - Reference

Read more here: » Completeness order theory: Encyclopedia - Completeness order theory

Ether used viewpoints to relativist information in publications. However a great deal of information is shared across viewpoints. So Ether made use of inheritance so that information in a viewpoint could be readily used in other viewpoints. Sometimes this inheritance is not exact as when the laws of physics in Newtonian mechanics are derived from those of Special Relativity. In such cases Ether used translation instead of inheritance. Bruno Latour has analyzed translation in scientific communities in the context of actor ...

See also:

Scientific Community Metaphor, Scientific Community Metaphor - Monotonicity Concurrency Commutatvity and Pluralism, Scientific Community Metaphor - Proposing Modifying Supporting and Opposing, Scientific Community Metaphor - Viewpoints Inheritance Translation and Negotiation, Scientific Community Metaphor - Emphasis on communities rather than individuals, Scientific Community Metaphor - Why is the Scientific Community Metaphor important now?, Scientific Community Metaphor - Reference

Read more here: » Scientific Community Metaphor: Encyclopedia II - Scientific Community Metaphor - Viewpoints Inheritance Translation and Negotiation

There are many extensions to Petri nets. Some of them are completely backwards-compatible (e.g. colored Petri nets) with the original Petri net, some add properties that cannot be modelled in the original Petri net (e.g. timed Petri nets). If they can be modelled in the original Peti net, they are not real extensions, instead are convenient ways of showing the same thing, and can be transformed with mathematical formulas back to the original Petri net, without loosing any meaning. Extensions that cannot be transfomed are sometimes very powerful, but usually lack the amount of mathematical tools ...

See also:

Petri net, Petri net - A Formal definition, Petri net - Basic Petri nets, Petri net - Basic mathematical properties, Petri net - Extensions, Petri net - Petri net theory, Petri net - Main Petri net types, Petri net - Subsequent models of concurrency, Petri net - Application areas, Petri net - Programming tools

Read more here: » Petri net: Encyclopedia II - Petri net - Extensions

In concrete terms for Actor systems, typically we cannot observe the details by which the arrival order of messages for an Actor is determined. Attempting to do so affects the results and can even push the indeterminacy elsewhere. e.g., see metastability in electronics and arbiters. Instead of observing the internals of arbitration processes of Actor computations, we await outcomes. Indeterminacy in arbiters produces indeterminacy in Actors. The reason tha ...

See also:

Indeterminacy in computation, Indeterminacy in computation - A limitation of logic programming, Indeterminacy in computation - Arrival order indeterminacy, Indeterminacy in computation - A limitation of logic due to lack of information, Indeterminacy in computation - Prolog-like concurrent systems were claimed to be based on mathematical logic, Indeterminacy in computation - Logical operations and system efficiency, Indeterminacy in computation - Indeterminacy in other models of computation

Read more here: » Indeterminacy in computation: Encyclopedia II - Indeterminacy in computation - Arrival order indeterminacy

Synchronous channels have the property that a sender putting a message in the channel must wait for a receiver to get the message out of the channel before the sender can proceed. Actor model and process calculi - Simple synchronous channels. A synchronous channel can be modeled by an Actor that receives put and get communications. The following is the behavior of an Actor for a simple synchronous channel: Each put communication has a message and an address to which ...

See also:

Actor model and process calculi, Actor model and process calculi - How do channels work?, Actor model and process calculi - Issues with synchronous channels, Actor model and process calculi - Simple synchronous channels, Actor model and process calculi - Synchronous channels in process calculi, Actor model and process calculi - Analogy with the committee coordination problem, Actor model and process calculi - A simple distributed protocol, Actor model and process calculi - Starvation on getting from multiple channels, Actor model and process calculi - Livelock on getting from multiple channels, Actor model and process calculi - Efficiency, Actor model and process calculi - Summary of Issues, Actor model and process calculi - Asynchronous channels, Actor model and process calculi - Simple asynchronouus channels, Actor model and process calculi - Asynchronous channels in process calculi, Actor model and process calculi - Migration, Actor model and process calculi - Algebras, Actor model and process calculi - Denotational Semantics

Read more here: » Actor model and process calculi: Encyclopedia II - Actor model and process calculi - Issues with synchronous channels

The denotational theory of computational system semantics is concerned with finding mathematical objects that represent what systems do. The theory makes use of a computational mathematical domains. Examples of such computational domains are partial functions and Actor event diagram scenarios. The relationship x≤y means that x can computationally evolve to y. If the denotations are partial functions, for example, f≤g may mean that f agrees with g on all values for which fSee also:

Denotational semantics, Denotational semantics - Fixed point semantics, Denotational semantics - Example of factorial function, Denotational semantics - Derivation of Scott Continuity from Actor Semantics, Denotational semantics - Full abstraction, Denotational semantics - Compositionality in programming languages, Denotational semantics - Environments, Denotational semantics - Arithmetic expressions, Denotational semantics - Delayed evaluation, Denotational semantics - Denotational semantics of concurrency, Denotational semantics - Early history of denotational semantics, Denotational semantics - Connections to other areas of computer science

Read more here: » Denotational semantics: Encyclopedia II - Denotational semantics - Fixed point semantics

Concurrent programming languages are programming languages that use language constructs for concurrency. These constructs may involve multi-threading, support for distributed computing, message passing, shared resources (including shared memory) or futures (known also as promises). Today, the most commonly used programming languages that have specific constructs for concurrency are Java and C#. Both of these languages fundamentally use a shared-memory concurrency model, with locking provided by monitors (although message-passin ...

See also:

Concurrent computing, Concurrent computing - Concurrent interaction and communication, Concurrent computing - Coordinating access to resources, Concurrent computing - Concurrent programming languages, Concurrent computing - Models of concurrency

Read more here: » Concurrent computing: Encyclopedia II - Concurrent computing - Concurrent programming languages