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Unraveling the Viral Spread of Misinformation: Maximum-Likelihood Estimation and Starlike Tree approximation in Markovian Spreading Models

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2025年 73卷 446-461页

作者： Yu, Pei-Duo Tan, Chee Wei Chung Yuan Christian Univ Taoyuan City 320314 Taiwan Nanyang Technol Univ Singapore 639798 Singapore

Identifying the source of epidemic-like spread in networks is crucial for removing internet viruses or finding the source of rumors in online social networks. The challenge lies in tracing the source from a snapshot observation of infected nodes. How do we accurately pinpoint the source? Utilizing snapshot data, we apply a probabilistic approach, focusing on the graph boundary and the observed time, to detect sources via an effective maximum likelihood algorithm. A novel starlike tree approximation extends applicability to general graphs, demonstrating versatility. Unlike previous works that rely heavily on structural properties alone, our method also incorporates temporal data for more precise source detection. We highlight the utility of the Gamma function for analyzing the ratio of the likelihood being the source between nodes asymptotically. Comprehensive evaluations confirm algorithmic effectiveness in diverse network scenarios, advancing source detection in large-scale network analysis and information dissemination strategies.

关键词： Fake news Maximum likelihood estimation Social networking (online) Probabilistic logic Signal processing algorithms Immune system Heuristic algorithms Focusing approximation algorithms Organizations Continuous-time SI model graph boundary analysis misinformation spreading network immunization rumor source detection starlike tree approximation

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approximation algorithms for resource allocation optimization

Approximation algorithms for resource allocation optimizatio...

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作者： Liao, Kewen University of Adelaide

学位级别：master

Nowadays, data storage, server replicas/mirrors, virtual machines, and various kinds of services can all be regarded as different types of resources. These resources play an important role in today’s computer world because of the continuing advances in information technology. It is usual that similar resources are grouped together at the same site, and can then be allocated to geographically distributed clients. This is the resource allocation paradigm considered in this thesis. Optimizing solutions to a variety of problems arising from this paradigm remains a key challenge, since these problems are NP-hard. For all the resource allocation problems studied in this thesis, we are given a set of sites containing facilities as resources, a set of clients to access these facilities, an opening cost for each facility, and a connection cost for each allocation of a facility to a client. The general goal is to decide the number of facilities to open at each site and allocate the open facilities to clients so that the total cost incurred is minimized. This class of the problems extends the classical NP-hard facility location problems with additional abilities to capture various practical resource allocation scenarios. To cope with the NP-hardness of the resource allocation problems, the thesis focuses on the design and analysis of approximation algorithms. The main techniques we adopt are linear programming based, such as primal-dual schema, linear program rounding, and reductions via linear programs. Our developed solutions have great potential for optimizing the performances of many contemporary distributed systems such as cloud computing, content delivery networks, Web caching, and Web services provisioning

关键词： approximation algorithms resource allocation optimization

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approximation ratio of the min-degree greedy algorithm for Maximum Independent Set on interval and chordal graphs

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DISCRETE APPLIED MATHEMATICS 2025年 360卷 275-281页

作者： Chaplick, Steven Frohn, Martin Kelk, Steven Lottermoser, Johann Mihalak, Matus Maastricht Univ Dept Adv Comp Sci DACS Maastricht Netherlands

In this article we prove that the minimum-degree greedy algorithm, with adversarial tie-breaking, is a (2/3)-approximation for the MAXIMUM INDEPENDENT SET problem on interval graphs. We show that this is tight, even on unit interval graphs of maximum degree 3. We show that on chordal graphs, the greedy algorithm is a (1/2)-approximation and that this is again tight. These results contrast with the known (tight) approximation ratio of 3/triangle+2 of the greedy algorithm for general graphs of maximum degree triangle. (c) 2024 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).

关键词： Greedy algorithms Maximum independent set Chordal graphs Interval graphs approximation algorithms

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Stochastic Halfspace approximation Method for Convex Optimization With Nonsmooth Functional Constraints

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 2025年第1期70卷 479-486页

作者： Singh, Nitesh Kumar Necoara, Ion Natl Univ Sci & Technol Politehn Bucharest Automat Control & Syst Engn Dept Bucharest 060042 Romania Romanian Acad Gheorghe Mihoc Caius Iacob Inst Math Stat & Appl M Roma TX USA

In this work, we consider convex optimization problems with smooth objective function and nonsmooth functional constraints. We propose a new stochastic gradient algorithm, called the stochastic halfspace approximation method (SHAM), to solve this problem, where at each iteration we first take a gradient step for the objective function and then we perform a projection step onto one halfspace approximation of a randomly chosen constraint. We propose various strategies to create this stochastic halfspace approximation and we provide a unified convergence analysis that yields new convergence rates for the SHAM algorithm in both optimality and feasibility criteria evaluated at some average point. In particular, we derive convergence rates of order O(1/root k) , when the objective function is only convex, and O(1/k) when the objective function is strongly convex. The efficiency of SHAM is illustrated through detailed numerical simulations.

关键词： Convergence Convex functions Linear programming approximation algorithms Signal processing algorithms Optimization Systems engineering and theory Convex optimization nonsmooth functional constraints stochastic halfspace approximation stochastic projection gradient methods

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approximation Algorithm and Applications for Connected Submodular Function Maximization Problems

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IEEE TRANSACTIONS ON NETWORKING 2025年第1期33卷 241-254页

作者： Wang, Ziming Li, Jing Xue, He Xu, Wenzheng Liang, Weifa Xu, Zichuan Peng, Jian Zhou, Pan Jia, Xiaohua Das, Sajal K. Sichuan Univ Coll Comp Sci Chengdu 610065 Peoples R China Sichuan Univ West China Hosp 2 Chengdu 610065 Peoples R China City Univ Hong Kong Dept Comp Sci Hong Kong Peoples R China Sichuan Fire Sci & Technol Res Inst MEM Chengdu 610065 Peoples R China Dalian Univ Technol Sch Software Dalian 116621 Peoples R China Huazhong Univ Sci & Technol Sch Cyber Sci & Engn Wuhan 430074 Peoples R China Missouri Univ Sci & Technol Dept Comp Sci Rolla MO 65409 USA

In this paper, we study a connected submodular function maximization problem, which arises from many applications including deploying UAV networks to serve users and placing sensors to cover Points of Interest (PoIs). Specifically, given a budget K , the problem is to find a subset S with K nodes from a graph G , so that a given submodular function f(S) on S is maximized and the induced subgraph G[S] by the nodes in S is connected, where the submodular function f can be used to model many practical application problems, such as the number of users within different service areas of the deployed UAVs in S , the sum of data rates of users served by the UAVs, the number of covered PoIs by placed sensors, etc. We then propose a novel 1-1/e/2h+2 -approximation algorithm for the problem, improving the best approximation ratio 1-1/e/2h+3 for the problem so far, through estimating a novel upper bound on the problem and designing a smart graph decomposition technique, where e is the base of the natural logarithm, h is a parameter that depends on the problem and its typical value is 2. In addition, when h=2 , the algorithm approximation ratio is at least 1-1/e/5 and may be as large as 1 in some special cases when K <= 23 , and is no less than 1-1/e/6 when K >= 24 , compared with the current best approximation ratio 1-1/e/7(=1-1/e/2h+3) for the problem. Finally, experimental results in the application of deploying a UAV network demonstrate that, the number of users within the service area of the deployed UAV network by the proposed algorithm is up to 7.5% larger than those by existing algorithms, and the throughput of the deployed UAV network by the proposed algorithm is up to 9.7% larger than those by the algorithms. Furthermore, the empirical approximation ratio of the proposed algorithm is between 0.7 and 0.99, which is close to the theoretical maximum value one.

关键词： Sensors Autonomous aerial vehicles approximation algorithms Disasters Wireless sensor networks Capacitive sensors Water pollution Social networking (online) Contamination Computer science UAV deployment sensor placement submodular function maximization approximation algorithms

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Streaming algorithms with Large approximation Factors 25

Streaming Algorithms with Large Approximation Factors

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25th International Conference on approximation algorithms for Combinatorial Optimization Problems and the 26th International Conference on Randomization and Computation, APPROX/RANDOM 2022

作者： Li, Yi Lin, Honghao Woodruff, David P. Zhang, Yuheng Division of Mathematical Sciences Nanyang Technological University Singapore Computer Science Department Carnegie Mellon University PittsburghPA United States Zhiyuan College Shanghai Jiao Tong University China

ISBN: (纸本)9783959772495

We initiate a broad study of classical problems in the streaming model with insertions and deletions in the setting where we allow the approximation factor α to be much larger than 1. Such algorithms can use significantly less memory than the usual setting for which α = 1 + ϵ for an ϵ ∈ (0, 1). We study large approximations for a number of problems in sketching and streaming, assuming that the underlying n-dimensional vector has all coordinates bounded by M throughout the data stream: 1. For the p norm/quasi-norm, 0 Θ(1), which holds even for randomly ordered streams or for streams in the bounded deletion model. 2. For estimating the p norm, p > 2, we show an upper bound of O(n1-2/p(log n log M)/α2) bits for an α-approximation, and give a matching lower bound for linear sketches. 3. For the 2-heavy hitters problem, we show that the known lower bound of Ω(k log n log M) bits for identifying (1/k)-heavy hitters holds even if we are allowed to output items that are 1/(αk)-heavy, provided the algorithm succeeds with probability 1 - O(1/n). We also obtain a lower bound for linear sketches that is tight even for constant failure probability algorithms. 4. For estimating the number 0 of distinct elements, we give an n1/t-approximation algorithm using O(t log log M) bits of space, as well as a lower bound of Ω(t) bits, both excluding the storage of random bits, where n is the dimension of the underlying frequency vector and M is an upper bound on the magnitude of its coordinates. 5. For α-approximation to the Schatten-p norm, we give near-optimal Õ(n2-4/p/α4) sketching dimension for every even integer p and every α ≥ 1, while for p not an even integer we obtain near-optimal sketching dimension once α = Ω(n1/q-1/p), where q is the largest even integer less than p. The latter is surprising as it is unknown what the complexity of Schatten-p norm estimation is for constant approximation;we show once the approximation factor is at least n1/q-1/p, we can obtain near-optimal sketc

关键词： approximation algorithms

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Hyperspectral Anomaly Detection Based on Tensor approximation With Tensor Double Nuclear Norm

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2025年 63卷

作者： Kong, Wenfeng Shen, Dunbin Li, Min Ma, Xiaorui Wang, Hongyu Dalian Univ Technol Sch Informat & Commun Engn Dalian 116024 Peoples R China

In hyperspectral anomaly detection (HAD), tensor low-rankness is essential for effectively separating background and anomaly. However, most of the current low-rank-based methods do not use the spatial-spectral low-rankness and the nonlocal self-similarity simultaneously. To address this issue, we propose a tensor double nuclear norm-based tensor approximation (TDNN-TA) model with all the priors in a unified convex framework, which can be efficiently handled through a well-organized alternating direction method of multipliers. Especially, to thoroughly model the background by tensor approximation, we propose a tensor double nuclear norm (TDNN), which achieves a more precise and flexible exploration of low-rankness and nonlocal self-similarity by applying different low-rank constraints to the global tensor and the group tensor. Moreover, to explore the intrinsic characteristics of different priors by various tensor ranks, we employ the Fourier transform-based three-directional tensor nuclear norm to approximate the nonlocal group tensor rank, and the framelet-based three-modal tensor nuclear norm to approximate the global tensor rank. Experimental results validated on several real hyperspectral datasets demonstrate that TDNN-TA is effective in detecting different sizes of anomalous targets and achieves competitive results for various scenes.

关键词： Tensors Anomaly detection Hyperspectral imaging TV Principal component analysis Dictionaries Detectors Geoscience and remote sensing Discrete Fourier transforms approximation algorithms Alternating direction method of multipliers hyperspectral anomaly detection (HAD) low-rankness nonlocal self-similarity

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approximation Non-list Scheduling algorithms for Multiprocessor System 1

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21st International Conference on Mathematical Optimization Theory and Operations Research , MOTOR 2022

作者： Grigoreva, Natalia St. Petersburg State University St. Petersburg Russia

ISBN: (数字)9783031162244

ISBN: (纸本)9783031162237

The multiprocessor scheduling problem is defined as follows: jobs have to be executed on several parallel identical processors. Each job has a positive processing time. At most one job can be processed at a time, but all jobs may be simultaneously delivered. We study the case where precedence constrains exist between jobs and preemption on processors is not allowed. The objective is to minimize the time, by which all jobs are done. The problem is NP-hard in the strong sense. The best-known approximation algorithm is the critical path algorithm, which generates the list no delay schedules. We define an IIT (inserted idle time) schedule as a feasible schedule, in which a processor is kept idle at a time when it could begin processing a job. The paper proposes a 2-1/m approximation inserted idle time algorithm for the multiprocessor scheduling. To illustrate the efficiency of our approach, we compared two algorithms on randomly generated sets of jobs. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： approximation algorithms

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Distributed fractional local ratio and independent set approximation

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INFORMATION AND COMPUTATION 2025年 303卷

作者： Halldorsson, Magnus M. Rawitz, Dror Reykjavik Univ Dept Comp Sci Reykjavik Iceland Bar Ilan Univ Fac Engn Ramat Gan Israel

We consider the MAXIMUM WEIGHT INDEPENDENT SET problem, with a focus on obtaining good approximations for graphs of small maximum degree A. We give deterministic local algorithms running in time poly(A, log n ) that come close to matching the best centralized results known and improve the previous distributed approximations by a factor of about 2. More precisely, we obtain approximations below Delta+1/2/2, and a further improvement to 8/5 + s when A = 3. Technically, this is achieved by leveraging the fractional local ratio technique, for a first application in a distributed setting. (c) 2024 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： approximation algorithms Distributed algorithms Fractional local ratio Maximum weight independent set

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Data-Driven Modeling of Weakly Nonlinear Circuits via Generalized Transfer Function approximation

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IEEE ACCESS 2025年 13卷 2746-2762页

作者： Carlucci, Antonio Gosea, Ion Victor Grivet-Talocia, Stefano Politecn Torino Dept Elect & Telecommun I-10129 Turin Italy Max Planck Inst Dynam Complex Tech Syst CSC Grp D-39106 Magdeburg Germany

This paper presents an extension of the Vector Fitting algorithm with the purpose of constructing compact behavioral models of weakly nonlinear circuits starting from frequency-domain input-output data. Using the concept of generalized transfer function provided by Volterra series theory for nonlinear systems, the algorithm approximates a given dataset of generalized transfer function samples with a black-box multivariate rational model. The fitted model can then be recast into a bilinear state-space form for time-domain analysis. Practical extraction of the required data samples can be carried out by measurement or harmonic balance analysis available in commercial solvers. Examples demonstrating the accuracy and efficiency of the behavioral models include a Low-Dropout Regulator and a Low Noise Amplifier.

关键词： Mathematical models Integrated circuit modeling Numerical models Transfer functions Nonlinear systems Data models Kernel Analytical models Time-domain analysis approximation algorithms Behavioral model nonlinear system vector fitting Volterra series data-driven model non-intrusive model reduction generalized transfer function

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