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Concurrent Constraint Logic Programming
Concurrent constraint logic programming is a version of constraint logic programming aimed primarily at programming concurrent processes rather than (or in addition to) solving constraint satisfaction problems. Goals in constraint logic programming are evaluated concurrently; a concurrent process is therefore programmed as the evaluation of a goal by the interpreter. Syntactically, concurrent constraint logic programs are similar to non-concurrent programs, the only exception being that clauses include guards, which are constraints that may block the applicability of the clause under some conditions. Semantically, concurrent constraint logic programming differs from its non-concurrent versions because a goal evaluation is intended to realize a concurrent process rather than finding a solution to a problem. Most notably, this difference affects how the interpreter behaves when more than one clause is applicable: non-concurrent constraint logic programming recursively tries all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constraint Logic Programming
Constraint logic programming is a form of constraint programming, in which logic programming is extended to include concepts from constraint satisfaction. A constraint logic program is a logic program that contains constraints in the body of clauses. An example of a clause including a constraint is . In this clause, is a constraint; A(X,Y), B(X), and C(Y) are Literal (mathematical logic), literals as in regular logic programming. This clause states one condition under which the statement A(X,Y) holds: X+Y is greater than zero and both B(X) and C(Y) are true. As in regular logic programming, programs are queried about the provability of a goal, which itself may contain constraints in addition to literals. A proof for a goal is composed of clauses whose bodies are satisfiable constraints and literals that can in turn be proved using other clauses. Execution is performed by an interpreter, which starts from the goal and Recursion, recursively scans the clauses trying to prove the goa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deadlock (computer Science)
In concurrent computing, deadlock is any situation in which no member of some group of entities can proceed because each waits for another member, including itself, to take action, such as sending a message or, more commonly, releasing a lock. Deadlocks are a common problem in multiprocessing systems, parallel computing, and distributed systems, because in these contexts systems often use software or hardware locks to arbitrate shared resources and implement process synchronization. In an operating system, a deadlock occurs when a process or thread enters a waiting state because a requested system resource is held by another waiting process, which in turn is waiting for another resource held by another waiting process. If a process remains indefinitely unable to change its state because resources requested by it are being used by another process that itself is waiting, then the system is said to be in a deadlock. In a communications system, deadlocks occur mainly due to loss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programming Paradigms
A programming paradigm is a relatively high-level way to conceptualize and structure the implementation of a computer program. A programming language can be classified as supporting one or more paradigms. Paradigms are separated along and described by different dimensions of programming. Some paradigms are about implications of the execution model, such as allowing side effects, or whether the sequence of operations is defined by the execution model. Other paradigms are about the way code is organized, such as grouping into units that include both state and behavior. Yet others are about syntax and grammar. Some common programming paradigms include (shown in hierarchical relationship): * Imperative code directly controls execution flow and state change, explicit statements that change a program state ** procedural organized as procedures that call each other ** object-oriented organized as objects that contain both data structure and associated behavior, uses data struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constraint Logic Programming
Constraint logic programming is a form of constraint programming, in which logic programming is extended to include concepts from constraint satisfaction. A constraint logic program is a logic program that contains constraints in the body of clauses. An example of a clause including a constraint is . In this clause, is a constraint; A(X,Y), B(X), and C(Y) are Literal (mathematical logic), literals as in regular logic programming. This clause states one condition under which the statement A(X,Y) holds: X+Y is greater than zero and both B(X) and C(Y) are true. As in regular logic programming, programs are queried about the provability of a goal, which itself may contain constraints in addition to literals. A proof for a goal is composed of clauses whose bodies are satisfiable constraints and literals that can in turn be proved using other clauses. Execution is performed by an interpreter, which starts from the goal and Recursion, recursively scans the clauses trying to prove the goa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alice (programming Language)
Alice ML is a general-purpose, high-level, multi-paradigm, functional programming language designed by the Programming Systems Laboratory at Saarland University, Saarbrücken, Germany. It is a dialect of Standard ML, augmented with support for lazy evaluation, concurrency ( multithreading and distributed computing via remote procedure calls) and constraint programming. Overview Alice extends Standard ML in a number of ways that distinguish it from its predecessor. Alice provides concurrency features as part of the base language through the use of a ''future'' type that represents a value being provided by an independent thread of execution. A thread that uses a future value will block on an attempt to access the value until the thread performing it has completed the computation. A related concept is also provided termed a '' promise'', allowing a thread to provide a future value that it will compute to another thread. Future and promise typed variables are used to implemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Janus (concurrent Constraint Programming Language)
Janus is a computer programming language partially described by K. Kahn and Vijay A. Saraswat in the paper "Actors as a special case of concurrent constraint (logic) programming" in 1990. It is a concurrent constraint language without backtracking. Janus models concurrency through the use of ''bag channels''. Code that needs to send a message to a process does so by constraining a bag to be the union of another bag and the singleton bag of the message. The other bag is then available to be constrained for sending subsequent messages. The process receives the message by matching the bag to a pattern that says it is the union of some singleton and some other bag. The logic of the bag channels produces a property shared by the actor model, namely that the order of arrival of the messages is not guaranteed. However, unlike actors in the actor model, processes in Janus can pass around their "mailboxes" so to speak, in the form of bags, and can hold more than one. This ability to pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curry (programming Language)
Curry is a declarative programming language, an implementation of the functional logic programming paradigm, and based on the Haskell language. It merges elements of functional and logic programming, including constraint programming integration. It is nearly a superset of Haskell but does not support all language extensions of Haskell. In contrast to Haskell, Curry has built-in support for non-deterministic computations involving search. Foundations of functional logic programming Basic concepts A functional program is a set of functions defined by equations or rules. A functional computation consists of replacing subexpressions by equal (with regard to the function definitions) subexpressions until no more replacements (or reductions) are possible and a value or normal form is obtained. For instance, consider the function double defined by double x = x+x The expression “” is replaced by . The latter can be replaced by if we interpret the operator “” to be defined ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michael J
Michael may refer to: People * Michael (given name), a given name * he He ..., a given name * Michael (surname), including a list of people with the surname Michael Given name * Michael (bishop elect)">Michael (surname)">he He ..., a given name * Michael (surname), including a list of people with the surname Michael Given name * Michael (bishop elect), English 13th-century Bishop of Hereford elect * Michael (Khoroshy) (1885–1977), cleric of the Ukrainian Orthodox Church of Canada * Michael Donnellan (fashion designer), Michael Donnellan (1915–1985), Irish-born London fashion designer, often referred to simply as "Michael" * Michael (footballer, born 1982), Brazilian footballer * Michael (footballer, born 1983), Brazilian footballer * Michael (footballer, born 1993), Brazilian footballer * Michael (footballer, born February 1996), Brazilian footballer * Michael (footballer, born March 1996), Brazilian footballer * Michael (footballer, born 1999), Brazilian football ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Logic Programming
Concurrent logic programming is a variant of logic programming designed for parallel computing in which programs are sets of guarded Horn clauses of the form: : The conjunction is called the guard of the clause, and is the commitment operator. Declaratively, guarded Horn clauses are read as ordinary logical implications: : However, procedurally, when there are several clauses whose heads match a given goal, then all of the clauses are executed in parallel, checking whether their guards hold. If the guards of more than one clause hold, then a committed choice is made to one of the clauses, and execution proceeds with the subgoals of the chosen clause. These subgoals can also be executed in parallel. Thus concurrent logic programming implements a form of "don't care nondeterminism", rather than "don't know nondeterminism". History The first concurrent logic programming language was the Relational Language of Keith L. Clark and Steve Gregory, which was an offshoot of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entailment
Logical consequence (also entailment or logical implication) is a fundamental concept in logic which describes the relationship between statements that hold true when one statement logically ''follows from'' one or more statements. A valid logical argument is one in which the conclusion is entailed by the premises, because the conclusion is the consequence of the premises. The philosophical analysis of logical consequence involves the questions: In what sense does a conclusion follow from its premises? and What does it mean for a conclusion to be a consequence of premises?Beall, JC and Restall, Greg, Logical Consequence' The Stanford Encyclopedia of Philosophy (Fall 2009 Edition), Edward N. Zalta (ed.). All of philosophical logic is meant to provide accounts of the nature of logical consequence and the nature of logical truth. Logical consequence is necessary and formal, by way of examples that explain with formal proof and models of interpretation. A sentence is said to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Process
Concurrent computing is a form of computing in which several computations are executed '' concurrently''—during overlapping time periods—instead of ''sequentially—''with one completing before the next starts. This is a property of a system—whether a program, computer, or a network—where there is a separate execution point or "thread of control" for each process. A ''concurrent system'' is one where a computation can advance without waiting for all other computations to complete. Concurrent computing is a form of modular programming. In its paradigm an overall computation is factored into subcomputations that may be executed concurrently. Pioneers in the field of concurrent computing include Edsger Dijkstra, Per Brinch Hansen, and C.A.R. Hoare. Introduction The concept of concurrent computing is frequently confused with the related but distinct concept of parallel computing, Pike, Rob (2012-01-11). "Concurrency is not Parallelism". ''Waza conference'', 11 Janua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
