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Parameterized algorithms for Balanced Cluster Edge Modification Problems

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arXiv 2024年

作者： Madathil, Jayakrishnan Meeks, Kitty University of Glasgow United Kingdom

We study Cluster Edge Modification problems with constraints on the size of the clusters. A graph G is a cluster graph if every connected component of G is a clique. In a typical Cluster Edge Modification problem such as the widely studied Cluster Editing, we are given a graph G and a non-negative integer k as input, and we have to decide if we can turn G into a cluster graph by way of at most k edge modifications-that is, by adding or deleting edges. In this paper, we study the parameterized complexity of such problems, but with an additional constraint: The size difference between any two connected components of the resulting cluster graph should not exceed a given threshold. Depending on which modifications are permissible-only adding edges, only deleting edges, both adding and deleting edges-we have three different computational problems. We show that all three problems, when parameterized by k, admit single-exponential time FPT algorithms and polynomial kernels. Our problems may be thought of as the size-constrained or balanced counterparts of the typical Cluster Edge Modification problems, similar to the well-studied size-constrained or balanced counterparts of other clustering problems such as k-Means Clustering. © 2024, CC BY.

关键词： consensus algorithm

Analysis of Effects of Communication Conditions on Distributed Secondary Control for DC Microgrids

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Analysis of Effects of Communication Conditions on Distribut...

International Conference on Power Electronics and Motion Control (IPEMC)

作者： Run Li Sucheng Liu Mengyu Xia Xiaodong Liu Anhui Province Key Laboratory of Power Electronics and Motion Control Anhui University of Technology Ma’anshan China

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

Distributed control strategies based on consensus algorithms for DC microgrids have gained intensive interest in recent years thanks to its advantages of high reliability, resilience, and expandability, over centralized control ones. Thus, global information can be accurately shared in a distributed way by sharing information between neighbor units. Meanwhile, hierarchical control paradigm consisting of three levels, i.e., primary, secondary, and tertiary, has become a standard solution for DC microgrids. Usually, the primary control is performed locally without communication, while secondary and tertiary controls desire distributed communication to obtain average voltage or current among units. Thus, the sparse communications are crucial to distributed control of DC microgrids. In this work, three main communication conditions, i.e., link failure, communication delay, and noise are included in analyzing effects of these conditions on distributed control of DC microgrids. Simulation model is built to verify the analysis in MATLAB/Simulink environment.

关键词： Analytical models Decentralized control Microgrids consensus algorithm Steady-state Delays Voltage control

Corridor Generating algorithm for Multi-Agent Pathfinding

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arXiv 2024年

作者： Pertzovsky, Arseniy

In this paper, we solve the classical Multi-agent Pathfinding (MAPF) problem. Existing approaches struggle to solve dense MAPF instances. In this paper, we propose a Corridor Generating algorithm for MAPF, namely CGA-MAPF. In CGA-MAPF, the agents build corridors, a set of connected vertices, from current locations towards agents’ goals and evacuate other agents out of the corridors to avoid collisions and deadlocks. The proposed algorithm has a reachability property, i.e. every agent is guaranteed to reach its goal location at some point. In the experimental section, we demonstrate that CGA-MAPF outperforms baseline algorithms in terms of success rate across diverse MAPF benchmark grids, achieving state-of-the-art performance. © 2024, CC BY.

关键词： consensus algorithm

Cyber Physical Implementation of Improved Distributed Secondary Control of DC Microgrid

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Cyber Physical Implementation of Improved Distributed Second...

Power Electronics and Energy (ICPEE), International Conference on

作者： Nataraj Pragallapati Satish J Ranade Olga Lavrova New Mexico State University Las Cruces USA

ISBN: (数字)9781728187747

ISBN: (纸本)9781728187754

This paper presents a cyber physical system implementation of an improved distributed secondary control (IDSC) scheme of islanded dc microgrid (DCMG). The IDSC scheme mitigates the hidden issues of primary control with included droop technique for the distributed generation unit (DGU) in a DCMG by providing the adjustable voltage compensation, improves voltage regulation and enhances the current sharing of all DGUs. The voltage compensation of IDSC is the resultant of two voltage components, i.e., average distributed integral voltage controller and average current controller. The dynamic consensus algorithm is used to obtain the global average values in the for distributed secondary controlusing relatively low bandwidth communication. The impact of communication time delay on the stability in IDSC based DCMG with two DGUs is presented. The performance of IDSC scheme is validated on a microgrid scenario, which includes parallel connection of four DGUs and common load. The real-time cyber physical system of DCMG is implemented on OP AL-RT test platform that combines the device layer on FPGA, control and cyber layers on CPU of OP5700 by using eFPGASim and RT-LAB.

关键词： Heuristic algorithms Microgrids consensus algorithm Bandwidth Real-time systems Voltage control System implementation

Parallel Greedy Best-First Search with a Bound on the Number of Expansions Relative to Sequential Search

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arXiv 2024年

作者： Shimoda, Takumi Fukunaga, Alex Graduate School of Arts and Sciences The University of Tokyo Japan

Parallelization of non-admissible search algorithms such as GBFS poses a challenge because straightforward parallelization can result in search behavior which significantly deviates from sequential search. Previous work proposed PUHF, a parallel search algorithm which is constrained to only expand states that can be expanded by some tie-breaking strategy for GBFS. We show that despite this constraint, the number of states expanded by PUHF is not bounded by a constant multiple of the number of states expanded by sequential GBFS with the worst-case tie-breaking strategy. We propose and experimentally evaluate One Bench At a Time (OBAT), a parallel greedy search which guarantees that the number of states expanded is within a constant factor of the number of states expanded by sequential GBFS with some tie-breaking policy. Copyright © 2024, The Authors. All rights reserved.

关键词： consensus algorithm

Optimization and Simulation of IOTA Blockchain Based on Optimized Decision Tree algorithm

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Optimization and Simulation of IOTA Blockchain Based on Opti...

Telecommunications, Electronics and Informatics (ICTEI), International Conference on

作者： Hong Liang Guangxi Polytechnic of Construction Nanning Jiangsu China

ISBN: (数字)9798350342963

ISBN: (纸本)9798350342970

With the growth of internet of things (IoT), 5G communication, artificial intelligence and other technologies, more and more intelligent application scenarios emerge, which put forward higher and higher requirements for the security and reliability of the computing process. The IoT has gradually developed from the traditional information interaction mode between people on the Internet to the interconnection between things. However, the IoT has brought so many functions, but its development has been restricted by some problems, such as limited resources, high running costs of central institutions and vulnerability to security attacks. In this article, an IOTA blockchain consensus algorithm based on optimized decision tree is proposed, and the proposed algorithm is simulated. The simulation results show that the accuracy of this algorithm can reach 97.88%. This method can effectively meet the privacy publishing requirements of dynamic data, and at the same time ensure the availability of published data. This algorithm can make the participating consensus nodes in the whole blockchain network reach a consensus quickly through the physical carrier sense of the current channel and setting the information transmission strategy between nodes when the transmission information between IoT devices is uncertain and the channel is unstable.

关键词： Data privacy Accuracy Publishing Heuristic algorithms consensus algorithm consensus protocol Internet of Things

Graph isomorphism and multivariate graph spectrum

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arXiv 2024年

作者： Wang, Wei Zhao, Da Department of Mathematics Xi’an Jiaotong University Xi’an China School of Mathematics East China University of Science and Technology Shanghai China

We provide a criterion to distinguish two graphs which are indistinguishable by 2-dimensional Weisfeiler-Lehman algorithm for almost all graphs. Haemers conjectured that almost all graphs are identified by their spectrum. Our approach suggests that almost all graphs are identified by their generalized block Laplacian *** Codes 05C50, 05C60 © 2024, CC BY-NC-ND.

关键词： consensus algorithm

Byzantine Fault Tolerance in the Partitioned Synchronous System Model

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Byzantine Fault Tolerance in the Partitioned Synchronous Sys...

Brazilian Symposium on Computing System Engineering (SBESC)

作者： Wellington Lacerda Silveira da Silva Marco Antonio Dantas Ramos Raimundo Jose de Araujo Macedo Distributed Systems Laboratory Federal University of Bahia Salvador Bahia Universidade Federal da Bahia Salvador BA BR

ISBN: (纸本)9781728102412;9781728102405

Byzantine fault tolerance was introduced to implement systems capable of tolerating arbitrary component failures, where n - f replicated state machines maintain their state consistent despite the action of up to f arbitrarily or Byzantine faulty state machines, for n ≥ 3f + 1. This notion was extended later for tolerating malicious attacks or intrusions when some of the systems components get compromised by a malicious intruder or attacker. Due to its high costs in terms of minimum needed redundancy (minimum 3f + 1 replicas), and related latency, several authors have turned their attention to alternative approaches where faulty processes can be excluded from the system adapting the current quorum of operational processes. In this paper, we explore the Partitioned Synchronous distributed system model, which suits existing real systems, such as large computational grids and distributed industrial plants, to propose a new Byzantine failure detector and related consensus algorithm for such a model. From our simulations we show that our approach indeed improves resilience when compared to static quorum approaches, with the continuous detection of faulty processes.

关键词： Detectors Computational modeling consensus algorithm Task analysis Communication channels Fault tolerance Fault tolerant systems

Extending the Extension: Deterministic algorithm for Non-monotone Submodular Maximization

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arXiv 2024年

作者： Buchbinder, Niv Feldman, Moran Department of Statistics and Operations Research Tel Aviv University Department of Computer Science University of Haifa

Maximization of submodular functions under various constraints is a fundamental problem that has been studied extensively. A powerful technique that has emerged and has been shown to be extremely effective for such problems is the following. First, a continues relaxation of the problem is obtained by relaxing the (discrete) set of feasible solutions to a convex body, and extending the discrete submodular function f to a continuous function F known as the multilinear extension. Then, two algorithmic steps are implemented. The first step approximately solves the relaxation by finding a fractional solution within the convex body that approximately maximizes F;and the second step rounds this fractional solution to a feasible integral solution. While this "fractionally solve and then round" approach has been a key technique for resolving many questions in the field, the main drawback of algorithms based on it is that evaluating the multilinear extension may require a number of value oracle queries to f that is exponential in the size of f’s ground set. The only known way to tackle this issue is to approximate the value of F via sampling, which makes all algorithms based on this approach inherently randomized and quite slow. In this work, we introduce a new tool, that we refer to as the extended multilinear extension, designed to derandomize submodular maximization algorithms that are based on the successful "solve fractionally and then round" approach. We demonstrate the effectiveness of this new tool on the fundamental problem of maximizing a submodular function subject to a matroid constraint, and show that it allows for a deterministic implementation of both the fractionally solving step and the rounding step of the above approach. As a bonus, we also get a randomized algorithm for the problem with an improved query *** Codes 68R05 (Primary) 68Q87, 68W40 (Secondary) Copyright © 2024, The Authors. All rights reserved.

关键词： consensus algorithm