Compared to the non-cooperative mode, the cooperative mode is a powerful way to reduce operational cost in pickup and delivery service. In order to protect business sensitive information, sometimes participants are un...
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Compared to the non-cooperative mode, the cooperative mode is a powerful way to reduce operational cost in pickup and delivery service. In order to protect business sensitive information, sometimes participants are unwilling to open the customer's detailed information. Thus, we utilize the publishable trip scheduled results to compute the saved trips brought by cooperation. A mathematical model minimizing trips of cooperation is proposed. To obtain the exact solution, we define the cooperative trip set. We prove that only when cooperative trip set exists it is possible to save trips by cooperation. For a two-trip cooperative trip set, we exactly obtain the saved trips by enumerating all feasible cooperative cases. For a K-trip cooperative trip set, we propose an exact method to obtain the saved trips by decomposing it to at most K-1 two-trip cooperative trip sets. Computational complexity of the based-on-decomposition exact algorithm is O(N), where N is the total number of trips. Using the based-on-decomposition algorithm, we calculate the exact Shapley value to distribute profit. To empirically verify the exact method, we perform the extensive experiment cases of the real cooperative pickup and delivery service, i.e., "picking up and delivering customers to airport service" (PDCA). (C) 2017 Elsevier Ltd. All rights reserved.
In Euclidean plane geometry, Apollonius' problem is to construct a circle in a plane that is tangent to three given circles. We will use a solution to this ancient problem to solve several versions of the followin...
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In Euclidean plane geometry, Apollonius' problem is to construct a circle in a plane that is tangent to three given circles. We will use a solution to this ancient problem to solve several versions of the following geometric optimization problem. Given is a set of customers located in the plane, each having a demand for a product and a budget. A customer is satisfied if her total, travel and purchase, costs do not exceed the budget. The task is to determine location of production facilities in the plane and one price for the product such that the revenue generated from the satisfied customers is maximized.
The b-chromatic number of a graph G, chi(b) (G), is the largest integer k such that G has a k-vertex coloring with the property that each color class has a vertex which is adjacent to at least one vertex in each of th...
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The b-chromatic number of a graph G, chi(b) (G), is the largest integer k such that G has a k-vertex coloring with the property that each color class has a vertex which is adjacent to at least one vertex in each of the other color classes. In the b-CHROMATIC NUMBER problem, the objective is to decide whether X-b(G) >= k. Testing whether Xb(G) = (G) 1, where A(G) is the maximum degree of a graph, itself is NP-complete even for connected bipartite graphs (Kratochvil, Tuza and Voigt, WG 2002). We show that b-CHROMATIC NUMBER is W[1]-hard when parameterized by k, resolving the open question posed by Havet and Sampaio (algorithmica 2013). When k = (G) 1, we design an algorithm for b-CHROMATIC NUMBER running in time 200'2 log k) n ro(i) Finally, we show that b-CHROMATIC NUMBER for an n-vertex graph can be solved in time 0(3nn4logn). (C) 2016 Elsevier Inc. All rights reserved.
In this paper, we first give the definition of randomized time-varying knapsack problems () and its mathematic model, and analyze the character about the various forms of . Next, we propose three algorithms for : (1) ...
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In this paper, we first give the definition of randomized time-varying knapsack problems () and its mathematic model, and analyze the character about the various forms of . Next, we propose three algorithms for : (1) an exact algorithm with pseudo-polynomial time based on dynamic programming;(2) a 2-approximation algorithm for based on greedy algorithm;(3) a heuristic algorithm by using elitists model based on genetic algorithms. Finally, we advance an evaluation criterion for the algorithm which is used for solving dynamic combinational optimization problems, and analyze the virtue and shortage of three algorithms above by using the criterion. For the given three instances of , the simulation computation results coincide with the theory analysis.
Background: Motifs are significant patterns in DNA, RNA, and protein sequences, which play an important role in biological processes and functions, like identification of open reading frames, RNA transcription, protei...
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Background: Motifs are significant patterns in DNA, RNA, and protein sequences, which play an important role in biological processes and functions, like identification of open reading frames, RNA transcription, protein binding, etc. Several versions of the motif search problem have been studied in the literature. One such version is called the Planted Motif Search (PMS) or (l, d)-motif Search. PMS is known to be NP complete. The time complexities of most of the planted motif search algorithms depend exponentially on the alphabet size. Recently a new version of the motif search problem has been introduced by Kuksa and Pavlovic. We call this version as the Motif Stems Search (MSS) problem. A motif stem is an l-mer (for some relevant value of l) with some wildcard characters and hence corresponds to a set of l-mers (without wildcards), some of which are (l, d)-motifs. Kuksa and Pavlovic have presented an efficient algorithm to find motif stems for inputs from large alphabets. Ideally, the number of stems output should be as small as possible since the stems form a superset of the motifs. Results: In this paper we propose an efficient algorithm for MSS and evaluate it on both synthetic and real data. This evaluation reveals that our algorithm is much faster than Kuksa and Pavlovic's algorithm. Conclusions: Our MSS algorithm outperforms the algorithm of Kuksa and Pavlovic in terms of the run time as well as the number of stems output. Specifically, the stems output by our algorithm form a proper (and much smaller) subset of the stems output by Kuksa and Pavlovic's algorithm.
The two-dimensional vector packing problem is a well-known generalization of the classical bin packing problem. It considers two attributes for each item and bin. Two capacity constraints must be satisfied in a feasib...
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The two-dimensional vector packing problem is a well-known generalization of the classical bin packing problem. It considers two attributes for each item and bin. Two capacity constraints must be satisfied in a feasible packing solution for each bin. The objective is to minimize the number of bins used. To compute optimal solutions for the problem, we propose a new branch-and-price algorithm. A goal cut that sets a lower bound to the objective is used. It is effective in speeding up column generation by reducing the number of iterations. To efficiently solve the pricing problem, we develop a branch-and-bound method with dynamic programming, which first eliminates conflicts between two items through branching, and then solves the two-constraint knapsack problem at leaf nodes through dynamic programming. Extensive computational experiments were conducted based on 400 test instances from existing literature. Our algorithm significantly outperformed the existing branch-and-price algorithms. Most of the test instances were solved within just a few seconds. (C) 2019 Elsevier B.V. All rights reserved.
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.
Global competitive priorities are undergoing a marked shift from productivity and quality to flexibility and agility. This has resulted in a growing number of manufacturing companies realizing the importance of buildi...
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Global competitive priorities are undergoing a marked shift from productivity and quality to flexibility and agility. This has resulted in a growing number of manufacturing companies realizing the importance of building customization capabilities into their production systems. Flexible assembly systems (FASs), consisting of a variety of processors such as assembly, inspection, packaging, and interactive operator consoles, provide a significant opportunity for improving product flexibility and, thereby, gaining sustainable competitive advantage. This paper formulates a decision problem for designing FASs and proves it to be NP-complete. A heuristic, called the pick and rule (PAR) heuristic, is presented to minimize the total number of processors, while determining the number of processors of each type, the sequence of the processors, and the operations to be performed at each processor. A lower bound for the minimum number of processor is derived, and used to assess the effectiveness of the PAR heuristic. An algorithm to compute this bound is also presented. An exact branch and bound algorithm is formulated to find optimal solutions and to provide guidance on the source of the gap between the PAR heuristic and the lower bound results. Computational results with the PAR heuristic, the lower bound algorithm, and the branch and bound algorithm are reported. (C) 2000 Elsevier Science B.V. All rights reserved.
The single facility location problem with demand regions seeks for a facility locationminimizing the sum of the distances from n demand regions to the facility. The demand regions represent sales markets where the tra...
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The single facility location problem with demand regions seeks for a facility locationminimizing the sum of the distances from n demand regions to the facility. The demand regions represent sales markets where the transportation costs are negligible. In this paper, we assume that all demand regions are disks of the same radius, and the distances are measured by a rectilinear norm, e.g. l(1) or l(infinity). We develop an exact combinatorial algorithm running in time O(n log(c) n) for some c dependent only on the space dimension. The algorithm is generalizable to the other polyhedral norms.
This paper proposes a four dimensional orthogonal packing and time scheduling problem. The problem differs from the classical packing problems in that the position and orientation of each item in the container can be ...
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This paper proposes a four dimensional orthogonal packing and time scheduling problem. The problem differs from the classical packing problems in that the position and orientation of each item in the container can be changed over time. In this way, the four dimensional space-time problem better uses the container time. Also, we consider a general case that all parameters are real numbers, which makes the problems more difficult to solve. This paper proposes an algorithm and proves that the algorithm could solve the problem optimally by a finite number of operations. We say this problem is weak computational, meaning that if there exists a universal machine that could represent real numbers and could do unit arithmetic or logical operation on real numbers in finite time, then the algorithm could find optimal solutions in finite time. This paper also presents a proof of the weak computability over a general case of the three dimensional orthogonal packing problem where all parameters are positive real numbers. (C) 2013 Elsevier B.V. All rights reserved.
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