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WalkSAT
In computer science, GSAT and WalkSAT are Local_search (optimization), local search algorithms to solve Boolean_satisfiability_problem, Boolean satisfiability problems. Both algorithms work on Well-formed formula, formulae in Boolean logic that are in, or have been converted into conjunctive normal form. They start by assigning a random value to each variable in the formula. If the assignment satisfies all Clause (logic), clauses, the algorithm terminates, returning the assignment. Otherwise, a variable is flipped and the above is then repeated until all the clauses are satisfied. WalkSAT and GSAT differ in the methods used to select which variable to flip. * GSAT makes the change which minimizes the number of unsatisfied clauses in the new assignment, or with some probability picks a variable at random. * WalkSAT first picks a clause which is unsatisfied by the current assignment, then flips a variable within that clause. The clause is picked at random among unsatisfied clauses. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satplan
Satplan (better known as Planning as Satisfiability) is a method for automated planning. It converts the planning problem instance into an instance of the Boolean satisfiability problem (SAT), which is then solved using a method for establishing satisfiability such as the DPLL algorithm or WalkSAT. The process encodes key elements of the planning problem—initial state, available actions, goal state, and a maximum plan length (horizon length)—into a logical formula. This formula is satisfiable ''if and only if'' a valid sequence of actions exists that transforms the initial state into the goal state within the given horizon. This concept is similar to Cook's theorem, where Turing machine A Turing machine is a mathematical model of computation describing an abstract machine that manipulates symbols on a strip of tape according to a table of rules. Despite the model's simplicity, it is capable of implementing any computer algori ... computations are represented as SAT for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Search (optimization)
In computer science, local search is a heuristic method for solving computationally hard Mathematical optimization, optimization problems. Local search can be used on problems that can be formulated as finding a solution that maximizes a criterion among a number of candidate solutions. Local Search algorithm, search algorithms move from solution to solution in the space of candidate solutions (the ''search space'') by applying local changes, until a solution deemed optimal is found or a time bound is elapsed. Local search algorithms are widely applied to numerous hard computational problems, including problems from computer science (particularly artificial intelligence), mathematics, operations research, engineering, and bioinformatics. Examples of local search algorithms are WalkSAT, the 2-opt, 2-opt algorithm for the Traveling Salesman Problem and the Metropolis–Hastings algorithm. While it is sometimes possible to substitute gradient descent for a local search algorithm, gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boolean Satisfiability Problem
In logic and computer science, the Boolean satisfiability problem (sometimes called propositional satisfiability problem and abbreviated SATISFIABILITY, SAT or B-SAT) asks whether there exists an Interpretation (logic), interpretation that Satisfiability, satisfies a given Boolean logic, Boolean Formula (mathematical logic), formula. In other words, it asks whether the formula's variables can be consistently replaced by the values TRUE or FALSE to make the formula evaluate to TRUE. If this is the case, the formula is called ''satisfiable'', else ''unsatisfiable''. For example, the formula "''a'' AND NOT ''b''" is satisfiable because one can find the values ''a'' = TRUE and ''b'' = FALSE, which make (''a'' AND NOT ''b'') = TRUE. In contrast, "''a'' AND NOT ''a''" is unsatisfiable. SAT is the first problem that was proven to be NP-complete—this is the Cook–Levin theorem. This means that all problems in the complexity class NP (complexity), NP, which includes a wide range of natu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bart Selman
Bart Selman is a Dutch-American professor of computer science at Cornell University. He is also co-founder and principal investigator of the Center for Human-Compatible Artificial Intelligence (CHAI) at the University of California, Berkeley, led by Stuart J. Russell, and co-chair of the Computing Community Consortium's 20-year roadmap for AI research. Education Selman attended the Technical University of Delft, from where he received a master's degree in physics, graduating in 1983. He received his master's and PhD in computer science from the University of Toronto in 1985 and 1991 respectively. Career Selman has been working at AT&T Bell Laboratories before becoming professor of computer science at Cornell University. His research areas include tractable inference, knowledge representation, stochastic search methods, theory approximation, knowledge compilation, planning, default reasoning, satisfiability solvers like WalkSAT, and connections between computer science an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constraint Programming
Constraint programming (CP) is a paradigm for solving combinatorial problems that draws on a wide range of techniques from artificial intelligence, computer science, and operations research. In constraint programming, users declaratively state the constraints on the feasible solutions for a set of decision variables. Constraints differ from the common primitives of imperative programming languages in that they do not specify a step or sequence of steps to execute, but rather the properties of a solution to be found. In addition to constraints, users also need to specify a method to solve these constraints. This typically draws upon standard methods like chronological backtracking and constraint propagation, but may use customized code like a problem-specific branching heuristic. Constraint programming takes its root from and can be expressed in the form of constraint logic programming, which embeds constraints into a logic program. This variant of logic programming is due ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logic In Computer Science
Logic in computer science covers the overlap between the field of logic and that of computer science. The topic can essentially be divided into three main areas: * Theoretical foundations and analysis * Use of computer technology to aid logicians * Use of concepts from logic for computer applications Theoretical foundations and analysis Logic plays a fundamental role in computer science. Some of the key areas of logic that are particularly significant are computability theory (formerly called recursion theory), modal logic and category theory. The theory of computation is based on concepts defined by logicians and mathematicians such as Alonzo Church and Alan Turing. Church first showed the existence of Undecidable problem, algorithmically unsolvable problems using his notion of lambda-definability. Turing gave the first compelling analysis of what can be called a mechanical procedure and Kurt Gödel asserted that he found Turing's analysis "perfect.". In addition some other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michael Trick
Michael Alan Trick is an operations researcher who studies combinatorial optimization, and is known for his work on sports scheduling, transportation scheduling, and social choice. He is the Harry B. and James H. Higgins Professor of Operations Research in the Tepper School of Business at Carnegie Mellon University (CMU), and dean of Carnegie Mellon University in Qatar. Trick earned a bachelor's degree in combinatorics and optimization and computer science from the University of Waterloo in 1982, a master's degree in operations research from the Georgia Institute of Technology (Georgia Tech) in 1984, and a PhD in industrial and systems engineering from Georgia Tech in 1987. His dissertation, ''Networks with Additional Structured Constraints'', was jointly supervised by John Bartholdi and H. Donald Ratliff. After postdoctoral research at the Institute for Mathematics and its Applications in Minneapolis and the Institut für Ökonometrie und Operations Research at the University of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David S
David (; , "beloved one") was a king of ancient Israel and Judah and the Kings of Israel and Judah, third king of the Kingdom of Israel (united monarchy), United Monarchy, according to the Hebrew Bible and Old Testament. The Tel Dan stele, an Canaanite and Aramaic inscriptions, Aramaic-inscribed stone erected by a king of Aram-Damascus in the late 9th/early 8th centuries BCE to commemorate a victory over two enemy kings, contains the phrase (), which is translated as "Davidic line, House of David" by most scholars. The Mesha Stele, erected by King Mesha of Moab in the 9th century BCE, may also refer to the "House of David", although this is disputed. According to Jewish works such as the ''Seder Olam Rabbah'', ''Seder Olam Zutta'', and ''Sefer ha-Qabbalah'' (all written over a thousand years later), David ascended the throne as the king of Judah in 885 BCE. Apart from this, all that is known of David comes from biblical literature, Historicity of the Bible, the historicit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bram Cohen
Bram Cohen is an American computer programmer, best known as the author of the peer-to-peer (P2P) BitTorrent protocol in 2001, as well as the first file sharing program to use the protocol, also known as BitTorrent. He is also the co-founder of CodeCon and organizer of the San Francisco Bay Area P2P-hackers meeting, was the co-author of Codeville and creator of the Chia cryptocurrency which implements the proof of space-time consensus algorithm. Early life and career Cohen grew up on the Upper West Side of Manhattan, New York City, as the son of a teacher and computer scientist. He claims he learned the BASIC programming language at the age of 5 on his family's Timex Sinclair computer. Cohen passed the American Invitational Mathematics Examination to qualify for the United States of America Mathematical Olympiad while he attended Stuyvesant High School in New York City. He graduated from Stuyvesant in 1993, and attended SUNY Buffalo. He later dropped out of college to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry Kautz
Henry A. Kautz (born 1956) is a computer scientist and a professor of computer science at the University of Virginia. He formerly served as the Founding Director of Institute for Data Science and Professor at University of Rochester. He is interested in knowledge representation, artificial intelligence, data science and pervasive computing. Biography Kautz was born in 1956 in Youngstown, Ohio. Kautz entered the Case Institute of Technology in 1974, then a year later, transferred to Cornell University and got his B.A. in English and in mathematics in 1978 there. He wrote plays during a one-year fellowship creative writing program at Johns Hopkins University and got an M.A. by the Writing Seminars in 1980. As a foreign student supported by the Connaught Fellowship, he enrolled at University of Toronto in 1980. Kautz completed his master thesis ''A First-Order Dynamic Logic for Planning'' under the supervision of C. Raymond Perrault, and then received his M.S. in computer science ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). 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 preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MAX-SAT
In computational complexity theory, the maximum satisfiability problem (MAX-SAT) is the problem of determining the maximum number of clauses, of a given Boolean formula in conjunctive normal form, that can be made true by an assignment of truth values to the variables of the formula. It is a generalization of the Boolean satisfiability problem, which asks whether there exists a truth assignment that makes all clauses true. Example The conjunctive normal form formula : (x_0\lor x_1)\land(x_0\lor\lnot x_1)\land(\lnot x_0\lor x_1)\land(\lnot x_0\lor\lnot x_1) is not satisfiable: no matter which truth values are assigned to its two variables, at least one of its four clauses will be false. However, it is possible to assign truth values in such a way as to make three out of four clauses true; indeed, every truth assignment will do this. Therefore, if this formula is given as an instance of the MAX-SAT problem, the solution to the problem is the number three. Hardness The MAX-SAT proble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
