We study the KNAPSACK problem with graph-theoretic constraints. That is, there exists a graph structure on the input set of items of KNAPSACK and the solution also needs to satisfy certain graph theoretic properties o...
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ISBN:
(纸本)9783031556005;9783031556012
We study the KNAPSACK problem with graph-theoretic constraints. That is, there exists a graph structure on the input set of items of KNAPSACK and the solution also needs to satisfy certain graph theoretic properties on top of the KNAPSACK constraints. In particular, we study CONNECTED KNAPSACK where the solution must be a connected subset of items which has maximum value and satisfies the size constraint of the knapsack. We show that this problem is strongly NP-complete even for graphs of maximum degree four and NP-complete even for star graphs. On the other hand, we develop an algorithm running in time O (2(O(tw log tw)) . poly(n) min{s(2), d(2)}) where tw, s, d, n are respectively treewidth of the graph, the size of the knapsack, the target value of the knapsack, and the number of items. We also exhibit a (1- epsilon) factor approximation algorithm running in time O (2(O(tw log tw)) . poly( n, 1/epsilon)) for every epsilon > 0. We show similar results for PATH KNAPSACK and Shortest PATH KNAPSACK, where the solution must also induce a path and shortest path, respectively. Our results suggest that CONNECTED KNAPSACK is computationally the hardest, followed by PATH KNAPSACK and then SHORTEST PATH KNAPSACK.
Mobile Network Operator (MNO)s avail the benefit of providing an isolated service with the network slice in a variety of forms like enhanced Mobile Broadband (eMBB), ultra Reliable Low Latency Communications (uRLLC), ...
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Mobile Network Operator (MNO)s avail the benefit of providing an isolated service with the network slice in a variety of forms like enhanced Mobile Broadband (eMBB), ultra Reliable Low Latency Communications (uRLLC), and massive Machine Type Communications (mMTC). However, they face challenges in handling situations of overload, congestion, and scaling with the arrival of unexpected control plane User Service Requests (USRs) leading to the dropping of USRs, and hence disturbing the slice's High Availability (HA). This paper presents a novel High Availability supportive self Reliant NEtwork Slicing System (HARNESS) for 5G Core, powered by intelligent and autonomous Self Organizing Network (SON) paradigm. In HARNESS, we propose algorithms to intelligently schedule and serve the significant portion of control plane USRs for both delay tolerant and delay sensitive slices, to ensure their uninterrupted HA service provision. Along with efficient resource utilization, the HARNESS shows improvements over the traditional HA provisioning methods, in preventing the occluding of crucial control plane USRs by 60% and reducing the average response time for these USRs by 50%. We developed the HARNESS framework in a 5G test-bed system using eXpress Data Path (XDP) and extended Berkeley Packet Filter (eBPF) mechanism for coherent and optimized end-to-end working of it. With this additional gear, HARNESS productively contributes to achieving 3.2% better slice service HA in the minimal two nodes active/active cluster configuration.
Dataset Versioning is extremely important for ensuring the reproducibility of results, tracking data changes over time, maintaining quality measures, enabling collaboration, and ensuring legal compliance. In this work...
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ISBN:
(纸本)9798350387117;9798350387124
Dataset Versioning is extremely important for ensuring the reproducibility of results, tracking data changes over time, maintaining quality measures, enabling collaboration, and ensuring legal compliance. In this work, we study the cost efficient data versioning problem, where the goal is to optimize the storage and reconstruction (retrieval) costs of data versions, given a graph of datasets as nodes and edges capturing edit/delta information. One central variant we study is MINSUM RETRIEVAL (MSR) where the goal is to minimize the total retrieval costs, while keeping the storage costs bounded. This problem (along with its variants) was introduced by Bhattacherjee et al. [VLDB'15]. While such problems are frequently encountered in collaborative tools (e.g., version control systems and data analysis pipelines), to the best of our knowledge, no existing research studies the theoretical aspects of these problems. We established, in the full version of this work(1), that the previous best heuristic, LMG (introduced in [VLDB'15]) can perform arbitrarily badly in a simple worst case. Moreover, we show that it is hard to get o(n)-approximation for MSR on general graphs even if we relax the storage constraints by an O(log n) factor. Similar hardness results are shown for other variants. Meanwhile, we propose poly-time approximation schemes for tree-like graphs, motivated by the fact that the graphs arising in practice from typical edit operations are often not arbitrary. As version graphs typically have low treewidth, we further develop new algorithms for bounded treewidth graphs. Furthermore, we propose two new heuristics and evaluate them empirically. First, we extend LMG by considering more potential "moves", to propose a new heuristic LMG-All. LMG-All consistently outperforms LMG while having comparable run time on a wide variety of datasets, i.e., version graphs. Secondly, we apply our tree algorithms on the minimum-storage arborescence of an instance, yielding algorith
In this paper we propose an algorithm based on the Tabu Search metaheuristic for the Map Labeling problem, i.e. the relevant problem in cartography of assigning labels to specific points of interests in a clear and re...
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ISBN:
(纸本)9783031574290;9783031574306
In this paper we propose an algorithm based on the Tabu Search metaheuristic for the Map Labeling problem, i.e. the relevant problem in cartography of assigning labels to specific points of interests in a clear and readable way. It is a combinatorial problem known to be NP- complete and therefore it needs to be tackled by means of good and efficient heuristics. In our experiments, we used real maps of Italian cities, Rome and Venice in particular.
Given a metric graph G = (V, E, w) and an integer k, we aim to find a single allocation k-hub location, which is a spanning subgraph consisting of a clique of size k such that every node outside of the clique is adjac...
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Given a metric graph G = (V, E, w) and an integer k, we aim to find a single allocation k-hub location, which is a spanning subgraph consisting of a clique of size k such that every node outside of the clique is adjacent to exactly one node inside the clique. For various objective functions studied in the literature, we present improved hardness and approximation results. (C) 2021 Elsevier B.V. All rights reserved.
The uniform bounded facility location problem (UBFLP) seeks for the optimal way of locating facilities to minimize total costs (opening costs plus routing costs), while the maximal routing costs of all clients are at ...
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The uniform bounded facility location problem (UBFLP) seeks for the optimal way of locating facilities to minimize total costs (opening costs plus routing costs), while the maximal routing costs of all clients are at most a given bound M. After building a mixed 0-1 integer programming model for UBFLP, we present the first constant-factor approximation algorithm with an approximation guarantee of 6.853+I mu for UBFLP on plane, which is composed of the algorithm by Dai and Yu (Theor. Comp. Sci. 410:756-765, 2009) and the schema of Xu and Xu (J. Comb. Optim. 17:424-436, 2008). We also provide a heuristic algorithm based on Benders decomposition to solve UBFLP on general graphes, and the computational experience shows that the heuristic works well.
Mobile-edge computing (MEC) has emerged as a promising paradigm for enabling Internet of Things (IoT) devices to handle computation-intensive jobs. Due to the imperfect parallelization of algorithms for job processing...
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ISBN:
(纸本)9798331540265;9798331540272
Mobile-edge computing (MEC) has emerged as a promising paradigm for enabling Internet of Things (IoT) devices to handle computation-intensive jobs. Due to the imperfect parallelization of algorithms for job processing on servers and the impact of IoT device mobility on data communication quality in wireless networks, it is crucial to jointly consider server resource allocation and IoT device mobility during job scheduling to fully benefit from MEC, which is often overlooked in existing studies. By jointly considering job scheduling, server resource allocation, and IoT device mobility, we investigate the deadline-constrained job offloading and resource management problem in MEC with both communication and computation contentions, aiming to maximize the total energy saved for IoT devices. For the offline version of the problem, where job information is known in advance, we formulate it as an Integer Linear Programming problem and propose an approximation algorithm, LHJS, with a constant performance guarantee. For the online version, where job information is only known upon release, we propose a heuristic algorithm, LBS, that is invoked whenever a job is released. Finally, we conduct experiments with parameters from real-world applications to evaluate their performance.
Emerging applications are imposing challenges for incorporating fairness constraints into k-center clustering in the streaming setting. Different from the traditional k-center problem, the fairness constraints require...
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ISBN:
(纸本)9789819722617;9789819722594
Emerging applications are imposing challenges for incorporating fairness constraints into k-center clustering in the streaming setting. Different from the traditional k-center problem, the fairness constraints require that the input points be divided into disjoint groups and the number of centers from each group is constrained by a given upper bound. Moreover, observing the applications of fair k-center inmassive datasets, we consider the problem in the streaming setting, where the data points arrive in a streaming manner that each point can be processed at its arrival. As themain contributions, we propose a two-pass streaming algorithm for the fair k-center problem with two groups, achieving an approximation ratio of 3 + epsilon and consuming only O(k log n) memory and O(k) update time, matching the state-of-art ratio for the offline setting. Then, we show that the algorithm can be easily improved to a one-pass streaming algorithm with an approximation ratio of 7+ epsilon and the same memory complexity and update time. Moreover, we show that our algorithm can be simply tuned to solve the case with an arbitrary number of groups while achieving the same ratio and space complexity. Lastly, we carried out extensive experiments to evaluate the practical performance of our algorithm compared with the state-of-the-art algorithms.
Given a set X of n points in a metric space and a radius R, we consider the combining version of k-center and k-median which is with the same objective as k-median, but with the constraint that any x in X is assigned ...
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ISBN:
(纸本)9789819723393;9789819723409
Given a set X of n points in a metric space and a radius R, we consider the combining version of k-center and k-median which is with the same objective as k-median, but with the constraint that any x in X is assigned to a center within the range R. In this paper, we propose a bicriteria approximation algorithm achieving a bicriteria approximation ratio of (3 + epsilon, 7), by incorporating local search with the technology of finding key balls with consequent center exchanges therein. Compared to the state-of-the-art approximation ratio of (8, 4) that is based on an LP formulation for k-median, we improve the ratio of the total distance from 8 to 3 + epsilon at the price of compromising the ratio of radius from 4 to 7.
There are many optimization problems having the following common property:Given a total task consisting of many subtasks,the problem asks to find a solution to complete only part of these *** include the k-Forest prob...
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There are many optimization problems having the following common property:Given a total task consisting of many subtasks,the problem asks to find a solution to complete only part of these *** include the k-Forest problem and the k-Multicut problem,*** problems are called partial optimization problems,which are often *** this paper,we systematically study the LP-rounding plus greed approach,a method to design approximation algorithms for partial optimization *** approach is simple,powerful and *** show how to use this approach to design approximation algorithms for the k-Forest problem,the k-Multicut problem,the k-Generalized connectivity problem,etc.
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