Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 36 for “"Exact algorithms"”.
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Robust Exact Algorithms for the Euclidean Bipartite Matching Problem
… this problem in O(n^3) time. There are many algorithms that have a run time better than that of the Hungarian algorithm if the graphs have non-negative integer edge costs bounded by C. Since the input points have real-valued coordinates and the Euclidean distances can be irrational, such …
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Relaxation and exact algorithms for solving mixed integer-quadratic optimization problems
We develop various algorithms for solving mixed integer-quadratic problems. These problems exhibit exponential complexity resulting from the presence of integer variables. Traditional approaches that apply in pure integer programming are not very helpful, since the existence of continuous variables …
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Exploiting structure to cope with NP-hard graph problems: Polynomial and exponential time exact algorithms
… time. When dealing with NP-hard problems, algorithms can only be expected to possess at most two out of these three desirable properties. All algorithms presented in this thesis are exact algorithms, which means that they always find an optimal solution. Demanding the solution to be optimal …
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Modeling, Analysis, and Exact Algorithms for Some Biomass Logistics Supply Chain Design and Routing Problems
… routing problems, and in developing effective exact algorithms for their solution. In the routing area, we have addressed extensions of the well-known traveling salesman and vehicle routing problems. We have proposed new formulations and have developed exact algorithms for the single and …
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On network coding capacity : matroidal networks and network capacity regions
… is a computable rational polytope and provide exact algorithms and approximation heuristics for computing the region. For the network linear coding capacity region, we construct a computable rational polytope, with respect to a given finite field, that inner bounds the linear coding capacity …
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On Algorithmic Progress in Data Structures and Approximation Algorithms
In the big data regime, computer systems and algorithms must process large amounts of data, making many traditional exact algorithms too costly to run. To work around this, researchers have developed approximation algorithms, which trade off some accuracy for asymptotic improvements in runtime, and …
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Analytical Investigations in Heat Exchanger Network Synthesis
Although exact algorithms have been successful in tackling HENS problems of small size, heuristics are required for large-scale problems, and nothing is known about the quality of the solutions provided by heuristics. Analytical investigations are suggested to characterize the behavior of both …
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Two Combinatorial Optimization Problems at the Interface of Computer Science and Operations Research
… is proven to be NP-hard. To solve this problem, exact algorithms and heuristic methods are presented. Different multi-objective problems with various numbers of objectives and constraints are used to compare the performances of the proposed algorithms and heuristics.
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Graph coloring algorithms on random graphs
… serve as a foundation for the developed algorithms. The various algorithms have been programmed and applied to random graphs. This dissertation will present several variations of the Korman algorithm, Korw2, Pactual, and Pactmaxw2, which produce exact colorings quicker than the Korman …
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Fine-grained complexity meets communication complexity
Fine-grained complexity aims to understand the exact exponent of the running time of fundamental problems in P. Basing on several important conjectures such as Strong Exponential Time Hypothesis (SETH), All-Pair Shortest Path Conjecture, and the 3-Sum Conjecture, tight conditional lower bounds are …
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Combinatorial optimization problems with concave costs
… of polynomial-time heuristics, approximation algorithms, and exact algorithms for classical combinatorial optimization problems immediately yield polynomial-time heuristics, approximation algorithms, and fully polynomial-time approximation schemes for the corresponding concave cost problems. …
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The polyhedral structure of certain combinatorial optimization problems with application to a naval defense problem
… cutting planes, can be implemented for obtaining exact and approximate solutions for various combinatorial optimization problems in the context of a branch-and-cut procedure. In particular, facets and valid cutting planes developed for the GUS constrained knapsack polytope and the set partitioning …
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A Massively Parallel Exact TSP Solver for Small Problem Sizes
… a set of cities such that each city is visited exactly once, and the tour ends in the starting city. This problem has gained attention among researchers because it is easy to describe yet difficult to solve. TSP has numerous important real-life applications, but its NP-hardness makes it …
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Efficient Algorithms for Graph-Theoretic and Geometric Problems
… placing firefighters. We provide both new exact algorithms for the case of general graphs as well as approximation algorithms for the case of planar graphs. Next, we study drawing graphs within a given polygon in the plane. We present asymptotically tight upper and lower bounds for this …
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Overcoming Computational Complexity Barriers for Optimal Transport in Discrete and Semi-Discrete Settings
… in this thesis is the following: 5. Efficient exact offline algorithm for $k$-server: We present an ${tilde{O}(n^{2-frac{1}{2d+1}}Phi(n)log Delta)}$ time algorithm for solving the instances of minimum-cost partial bipartite matching defined by the offline version of the $k$-server problem.
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Consensus Algorithms for Trees and Strings
… proofs, polynomial-time approximation algorithms, and polynomial-time exact algorithms indicate that these problems become computationally easier if the resulting tree is required to comply with a prespecified left-to-right ordering of the leaves. The second part of the thesis deals …
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Fair and Risk-Averse Resource Allocation in Transportation Systems under Uncertainties
… case, inspires us to develop efficient solution algorithms. We derive mixed-integer linear programming (MILP) formulations for these models, leveraging the unique properties of each model and linearizing non-linear terms. Additionally, we strengthen these models with valid inequalities. To …
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Metaheuristic algorithms for air-route optimization under climate change
… under climate-driven turbulence using both exact algorithms and metaheuristics. We first build a transparent baseline on synthetic grids and small airport networks where edge costs are still-air travel times. This allows reproducible comparisons between Dijkstra’s algorithm (exact, …
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The aircraft sequencing problem with arrivals and departures
… objective of minimizing total weighted delay. Exact algorithms for this problem are not fast enough for practical implementation. WP- give several algorithms that can be used both for the static and the dynamic versions of the problem. These algorithms are not exact solutions, however they are …
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Algorithms for Vertex-Weighted Matching in Graphs
… coarsen graphs in multi-level graph partitioning algorithms. In the first part of this thesis, we develop exact and approximation algorithms for vertex weighted matchings, an under-studied variant of the weighted matching problem. We propose three exact algorithms, three half approximation …
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