We study the problem of computing a minimum-width annulus with outliers. Specifically, given a set of n points in the plane and an integer k with 1 <= k <= n, the problem asks to find a minimum-width annulus tha...
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We study the problem of computing a minimum-width annulus with outliers. Specifically, given a set of n points in the plane and an integer k with 1 <= k <= n, the problem asks to find a minimum-width annulus that contains at least n - k input points. The k excluded points are considered as outliers of the input points. In this paper, we are interested in particular in annuli of three different shapes: circular, square, and rectangular annuli. For the three cases, we present first and improved algorithms to the problem. (C) 2019 Elsevier B.V. All rights reserved.
We address the two-dimensional Knapsack Problem (2YP), aimed at packing a maximum-profit subset of rectangles selected from a given set into another rectangle. We consider the natural relaxation of 2KP given by the on...
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We address the two-dimensional Knapsack Problem (2YP), aimed at packing a maximum-profit subset of rectangles selected from a given set into another rectangle. We consider the natural relaxation of 2KP given by the one-dimensional KP with item weights equal to the rectangle areas, proving the worst-case performance of the associated upper bound, and present and compare computationally four exact algorithms based on the above relaxation, showing their effectiveness. (C) 2003 Elsevier B.V. All rights reserved.
Geodesic offset curves are important for many industrial applications, such as solid modeling, robot-path planning, the generation of tool paths for NC machining, etc. Although the offset problem is well studied in cl...
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Geodesic offset curves are important for many industrial applications, such as solid modeling, robot-path planning, the generation of tool paths for NC machining, etc. Although the offset problem is well studied in classical differential geometry and computer-aided design, where the underlying surface is sufficiently smooth, very few algorithms are available for computing geodesic offsets on discrete representation, in which the input is typically a polyline curve restricted on a piecewise linear mesh. In this paper, we propose an efficient and exact algorithm to compute the geodesic offsets on triangle meshes by extending the Xin-Wang algorithm of discrete geodesics. We define a new data structure called parallel-source windows, and extend both the "one angle one split" and the filtering theorem to maintain the window tree. Similar to the original Xin-Wang algorithm, our extended algorithm has an O(n) space complexity and an O(n(2) log n) asymptotic time complexity, where n is the number of vertices on the input mesh. We tested our algorithm on numerous real-world models and showed that our algorithm is exact, efficient and robust, and can be applied to large scale models with complicated geometry and topology. (C) 2011 Elsevier Ltd. All rights reserved.
Interesting itemset mining is a fundamental research problem in knowledge management and machine learning. It is intended to identify interesting relations between variables in a database using some measures of intere...
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Interesting itemset mining is a fundamental research problem in knowledge management and machine learning. It is intended to identify interesting relations between variables in a database using some measures of interestingness and has a number of applications, including market basket analysis, web usage mining, intrusion detection, and many others. This paper proposes a new interestingness measure, the fault-tolerant tile. That is based on two observations: (1) the length of an itemset can be as important as its frequency;(2) knowledge discovery from real-world datasets calls for fault -tolerant data mining (e.g. extracting fault -tolerant association rules, analyzing noisy datasets). Given a user-defined fault tolerance value, we are interested in finding the maximum/top-k fault-tolerant tiles. Due to the exponential search space of candidate itemsets, both problems are NP-hard. While using some monotonic property to prune search space is a common strategy for interesting itemset mining, no monotonic property is available for this problem. To tackle the challenge, we utilize the branch-and-bound search strategy to analyze the characteristics of candidate itemsets at each searching branch and estimating their bounds. Our experimental results show that our algorithms can effectively analyze real datasets and retrieve meaningful results. (C) 2018 Elsevier Ltd. All rights reserved.
We consider MIN SET COVERING when the subsets are constrained to have maximum cardinality 3. We propose an exact algorithm whose worst-case complexity is bounded above by O*(1.3957(m)) where in is the number of sets i...
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We consider MIN SET COVERING when the subsets are constrained to have maximum cardinality 3. We propose an exact algorithm whose worst-case complexity is bounded above by O*(1.3957(m)) where in is the number of sets in the instance. This result improves upon the previously known bound of O*(1.4391(m)). (c) 2006 Elsevier B.V. All rights reserved.
Compared with the traditional assembly line, seru production can reduce worker(s) and decrease makespan. However, when the two objectives are considered simultaneously, Pareto-optimal solutions may save manpower but i...
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Compared with the traditional assembly line, seru production can reduce worker(s) and decrease makespan. However, when the two objectives are considered simultaneously, Pareto-optimal solutions may save manpower but increase makespan. Therefore, we formulate line-seru conversion towards reducing worker(s) without increasing makespan and develop exact and meta-heuristic algorithms for the different scale instances. Firstly, we analyse the distinct features of the model. Furthermore, according to the feature of the solution space, we propose two exact algorithms to solve the small to medium-scale instances. The first exact algorithm searches the solution space from more workers to fewer workers. The second exact algorithm searches the solution space from fewer workers to more workers. The two exact algorithms search a part of solution space to obtain the optimal solution of reducing worker(s) without increasing makespan. According to the variable length of the feasible solutions, we propose a variable-length encoding heuristic algorithm for the large-scale instances. Finally, we use the extensive experiments to evaluate the performance of the proposed algorithms and to investigate some managerial insights on when and how to reduce worker(s) without increasing makespan by line-seru conversion.
Maximal Clique Enumeration (MCE) is a fundamental and challenging problem in graph theory and various network applications. Numerous algorithms have been proposed in the past decades, however, only a few of them focus...
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Maximal Clique Enumeration (MCE) is a fundamental and challenging problem in graph theory and various network applications. Numerous algorithms have been proposed in the past decades, however, only a few of them focus on improving the practical efficiency in large graphs. To this end, we propose an efficient algorithm called FACEN based on the Bron-Kerbosch framework. To optimize the memory and time consumption, we apply a hybrid data structure with adjacency list and partial adjacency matrix, and introduce a dynamic pivot selection rule based on the degeneracy order. FACEN is evaluated on a total of 64 benchmark instances from various sources. Computational results indicate that the proposed algorithm is highly competitive with the current leading MCE methods. In particular, our algorithm is able to enumerate all maximal cliques on the tested real-world social networks with millions of vertices and edges. For very large graphs, we provide an additional experiment for solving the MCE variant with lower bound, and investigate the benefits of FACEN.
In this paper, we address the temporal knapsack problem (TKP), a generalization of the classical knapsack problem, where selected items enter and leave the knapsack at fixed dates. We model the TKP with a dynamic prog...
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In this paper, we address the temporal knapsack problem (TKP), a generalization of the classical knapsack problem, where selected items enter and leave the knapsack at fixed dates. We model the TKP with a dynamic program of exponential size, which is solved using a method called Successive Sublimation Dynamic Programming (SSDP). This method starts by relaxing a set of constraints from the initial problem, and iteratively reintroduces them when needed. We show that a direct application of SSDP to the temporal knapsack problem does not lead to an effective method, and that several improvements are needed to compete with the best results from the literature. (C) 2021 Elsevier B.V. All rights reserved.
In this paper, an exact algorithm based on the method of orienting curves is developed for solving the convex non-differentiable optimization problem on the closed unit cube in a finite dimensional space: finding the ...
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In this paper, an exact algorithm based on the method of orienting curves is developed for solving the convex non-differentiable optimization problem on the closed unit cube in a finite dimensional space: finding the shortest path joining two points going through a sequence of adjacent triangles in 3D. As a result, the global solution of the problem is determined successively by some orienting curves and final curve, which can be exactly constructed with ruler and compass. A detailed numerical example is presented.
In recent work, we have built upon seminal contributions of Montroll and Weiss to develop invariance relations for random walks on k = 2 hexagonal and square-planar lattices. In this study, we extend our approach to d...
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In recent work, we have built upon seminal contributions of Montroll and Weiss to develop invariance relations for random walks on k = 2 hexagonal and square-planar lattices. In this study, we extend our approach to determine invariance relations for random walks on k = 3 finite, simple cubic lattices subject to periodic boundary conditions. Use of these invariance relations allows one to calculate estimates of the overall mean walklength before trapping, and we show that the results obtained are in excellent agreement with numerically-exact calculated values. The results and analysis presented here yield insights on the problem of self-avoiding walks on cubic lattices. (c) 2006 Elsevier B.V. All rights reserved.
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