Search for dissertations about: "approximation"

Showing result 6 - 10 of 1037 swedish dissertations containing the word approximation.

  2. 6. Label Cover Reductions for Unconditional Approximation Hardness of Constraint Satisfaction

    Author : Cenny Wenner; Johan Håstad; Viggo Kann; Irit Dinur; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Combinatorial Optimization; Complexity Theory; Approximation; Approximability; Inapproximability; Computational Hardness; NP; Optimization; Constraint Satisfaction; Kombinatorisk optimering; Komplexitetsteori; Beräkningsteori; Approximation; Approximerbarhet; Beräkningssvårighet; NP; Optimering; Vilkorssatisfiering; Vilkorsuppfyllning; Vilkorstillfredställand; datalogi; Computer Science;

    Abstract : Combinatorial optimization include such tasks as finding the quickest route to work, scheduling jobs to specialists, and placing bus stops so as to minimize commuter times. We consider problems where one is given a collection of constraints with the objective of finding an assignment satisfying as many constraints as possible, also known as Constraint Satisfaction Problems (CSPs). READ MORE

  4. 7. Approximation Algorithms for Geometric Networks

    Author : Mattias Andersson; Data Vetenskap; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; control; systems; numerical analysis; Computer science; Geometric Networks; Computational Geometry; Approximation Algorithms; Datalogi; numerisk analys; system; kontroll; Systems engineering; computer technology; Data- och systemvetenskap;

    Abstract : The main contribution of this thesis is approximation algorithms for several computational geometry problems. The underlying structure for most of the problems studied is a geometric network. READ MORE

  5. 8. Label Cover Reductions for Unconditional Approximation Hardness of Constraint Satisfaction

    Author : Cenny Wenner; Johan Håstad; Irit Dinur; Numerical Analysis and Computer Science (NADA) Faculty of Science Stockholm University; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Optimization; NP; Approximation; Approximability; Inapproximability; Constraint Satisfaction; CSP; Boolean Analysis; Satisfiability; SAT; Acyclic Subgraph; Betweenness; Unique Games; Computer Science; Datalogi;

    Abstract : Problem solving is an integral aspect of modern society and includes such tasks as picking the fastest route to work, optimizing a production line, scheduling computer tasks, placing new bus stops, or picking a meal from available ingredients.We study the hardness of solving Constraint Satisfaction Problems (CSPs). READ MORE

  6. 9. Model Vertices Beyond the GW Approximation

    Author : Mikael Hindgren; Matematisk fysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; gravitation; GW approximation; Electron self energy; Green s function; consistency; local-field corrections; vertex function; conserving approximations; variational energies; Mathematical and general theoretical physics; classical mechanics; relativity; quantum mechanics; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:1997:Hindgren;

    Abstract : We study the effects of local vertex corrections to the self energy of the electron gas. We find that a vertex derived from time-dependent density-functional theory can give accurate self energies without including the explicit time dependence of the exchange-correlation potential provided, however, that a proper decay at large momentum transfer (large q) is built into the vertex function. READ MORE

  7. 10. Studies of the Boundary Behaviour of Functions Related to Partial Differential Equations and Several Complex Variables

    Author : Håkan Persson; Kaj Nyström; Maciej Klimek; Evgeny Poletsky; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; uniformly parabolic equations; non-linear parabolic equations; linear growth; Lipschitz domain; NTA-domain; Riesz measure; boundary behavior; boundary Harnack; degenerate parabolic; parabolic measure; plurisubharmonic functions; continuous boundary; hyperconvexity; bounded exhaustion function; Hölder for all exponents; log-lipschitz; boundary regularity; approximation; Mergelyan type approximation; plurisubharmonic functions on compacts; Jensen measures; monotone convergence; plurisubharmonic extension; plurisubharmonic boundary values; Mathematics; Matematik;

    Abstract : This thesis consists of a comprehensive summary and six scientific papers dealing with the boundary behaviour of functions related to parabolic partial differential equations and several complex variables.Paper I concerns solutions to non-linear parabolic equations of linear growth. READ MORE