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A Full DAG Score-Based algorithm for Learning Causal Bayesian Networks with Latent Confounders

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arXiv 2024年

作者： Gonzales, Christophe Valizadeh, Amir-Hosein Aix Marseille Univ CNRS LIS Marseille France

Causal Bayesian networks (CBN) are popular graphical probabilistic models that encode causal relations among variables. Learning their graphical structure from observational data has received a lot of attention in the literature. When there exists no latent (unobserved) confounder, i.e., no unobserved direct common cause of some observed variables, learning algorithms can be divided essentially into two classes: constraint-based and score-based approaches. The latter are often thought to be more robust than the former and to produce better results. However, to the best of our knowledge, when variables are discrete, no score-based algorithm is capable of dealing with latent confounders. This paper introduces the first fully score-based structure learning algorithm searching the space of DAGs (directed acyclic graphs) that is capable of identifying the presence of some latent confounders. It is justified mathematically and experiments highlight its effectiveness. © 2024, CC BY.

关键词： consensus algorithm

Selective Deletion in a Blockchain

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Selective Deletion in a Blockchain

International Conference on Distributed Computing Systems

作者： Peter Hillmann Marcus Knüpfer Erik Heiland Andreas Karcher Bundeswehr University Munich Neubiberg Germany

ISBN: (数字)9781728170022

ISBN: (纸本)9781728170039

The constantly growing size of blockchains becomes a challenge with the increasing usage. Especially the storage of unwanted data in a blockchain is an issue, because it cannot be removed naturally. In order to counteract this problem, we present the first concept for the selective deletion of single entries in a blockchain. For this purpose, the general consensus algorithm is extended by the functionality of regularly creating summary blocks. Previous data of the chain are summarized and stored again in a new block, leaving out unwanted information. With a shifting marker of the Genesis Block, data can be deleted from the beginning of a blockchain. In this way, the technology of the blockchain becomes fully transactional. The concept is independent of a specific block structure, network structure, or consensus algorithm. Moreover, this functionality can be adapted to current blockchains to solve multiple problems related to scalability. This approach enables the transfer of blockchain technology to further fields of application, among others in the area of Industry 4.0 and Product Life-cycle Management.

关键词： Industries Scalability Conferences Blockchain consensus algorithm Distributed computing

Blockchain-Based Scalability Solutions for IoT: A Decentralized Design to Enhance Performance and Security

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Blockchain-Based Scalability Solutions for IoT: A Decentrali...

IEEE International Conference on Electronics, Computing and Communication Technologies (CONECCT)

作者： Shweta Babu Prasad Ashok Kumar A. R Rajini V Honnungar Dept. of Computer Science and Engineering RV College of Engineering Dept. of Electronics and Communication Engineering RNS Institute of Technology

ISBN: (数字)9798350385922

ISBN: (纸本)9798350385939

The Internet-of-Things facilitates the interlinking of an extensive number of devices, each capable of executing independent functions and acquiring diverse forms of information. These entities, in conjunction with the copious quantities of data they generate, necessitate scalable, proficient and safe-guarded management. Centralized solutions are not desired due to security concerns and scalability issue. Alternative to the centralized system, Blockchain – a decentralized systems that is proven to be platform to support both integrity and security is a choice. But, as the IoT devices are resource constrained devices, deploying a blockchain for the data management is a challenging task. In this manuscript, we put forth a multi-layer blockchain framework that accomplishes the goal of achieving scalability and access control in Internet of Things (IoT), gadgets including data. This framework is comprised of numerous permissioned blockchains that come together to configure a multi-layer architecture. As a result, it also attains high scalability using parallel processing, specifically through the utilization of blockchain sharding schemes.

关键词： Access control Sharding Scalability Computer architecture consensus algorithm Parallel processing Communications technology

A Cross-Chain Protocol Based on Main-SubChain Architecture

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A Cross-Chain Protocol Based on Main-SubChain Architecture

Computer Science and Blockchain (CCSB), International Conference on

作者： Feng Zhang Yu Le Rong Wang Minfu Yuan Wei-Tek Tsai Yuansheng Dong China Mobile Information Security Management and Operation Center Beijing China Guangzhou Institute of Software Guangzhou China College of Computer and Data Science Fuzhou University Arizona State University Tempe AZ USA Huanggang Polytechnic College Huanggang China

ISBN: (数字)9798350356502

ISBN: (纸本)9798350356519

Addressing the current surge in blockchain applications and the increasingly significant throughput and scalability challenges of single-chain systems, we propose a cross-chain protocol based on a main-subchain architecture, utilizing a “ $1+\mathrm{N}$ ” model composed of a main blockchain and multiple sidechains. The main blockchain is a permissioned public blockchain that employs relay chain technology, combining the flexibility and scalability of public blockchains with the performance, security, and regulatory advantages of federated blockchains. It serves as the core of the architecture, managing and coordinating the operations of the sidechains. Sidechains maintain a high degree of independence, selecting consensus algorithms tailored to their specific business needs and processing transactions asynchronously across different chains. Cross-chain transactions are decomposed into multiple sub-transactions, which are independently processed and verified by the relevant sidechains and the committee blockchain. This architecture ensures the atomicity, consistency, and security of transactions while enhancing the system's parallel processing capability and overall performance. Finally, this paper demonstrates the superiority of the proposed scheme in terms of fund security, atomicity, consistency, continuity, and dynamics through theoretical analysis.

关键词： Protocols Scalability Computer architecture consensus algorithm Parallel processing Throughput Blockchains Security Surges Relays

Formation Control of Multi-UAV Systems using Zeroing Dynamics Method 2017

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Formation Control of Multi-UAV Systems using Zeroing Dynamic...

Proceedings of the 2017 2nd International Conference on Communication and Information Systems

作者： Rui Zhang Jianan Wang Yongshan Liu Chaoyong Li Jiayuan Shan School of Aerospace Engineering Beijing Institute of Technology School of Aerospace Engineering Beijing Institute of Technology Beijing China College of Electrical Engineering Zhejiang University

ISBN: (纸本)9781450353489

This paper deals with the formation control problem of multiple unmanned aerial vehicles (UAVs). The UAV models are considered highly nonlinear and only translational motion is considered. Zeroing dynamics was first adopted to tackle the position and velocity consensus and then extended to the application of formation control using a constant offset vector. The feasibility of the proposed algorithm was analyzed and simulation results of four UAVs' formation flying were shown to validate the effectiveness of the proposed formation control law.

关键词： formation control UAV consensus algorithm zeroing dynamics method

Finding missing items requires strong forms of randomness

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arXiv 2023年

作者： Chakrabarti, Amit Stoeckl, Manuel Department of Computer Science Dartmouth College HanoverNH03755 United States

Adversarially robust streaming algorithms are required to process a stream of elements and produce correct outputs, even when each stream element can be chosen as a function of earlier algorithm outputs. As with classic streaming algorithms, which must only be correct for the worst-case fixed stream, adversarially robust algorithms with access to randomness can use significantly less space than deterministic algorithms. We prove that for the Missing Item Finding problem in streaming, the space complexity also significantly depends on how adversarially robust algorithms are permitted to use randomness. (In contrast, the space complexity of classic streaming algorithms does not depend as strongly on the way randomness is used.) For Missing Item Finding on streams of length with elements in {1, ...,n}, and ≤ 1/poly() error, we show that when = O(2√logn), "random seed" adversarially robust algorithms, which only use randomness at initialization, require Ω(1) bits of space, while "random tape" adversarially robust algorithms, which may make random decisions at any time, may use O(polylog()) space. When is between nΩ(1) and O(√n), "random tape" adversarially robust algorithms need Ω(1) space, while "random oracle" adversarially robust algorithms, which can read from a long random string for free, may use O(polylog()) space. The space lower bound for the "random seed" case follows, by a reduction given in prior work, from a lower bound for pseudo-deterministic streaming algorithms given in this paper. © 2023, CC BY-SA.

关键词： consensus algorithm

Building a collaborative university teaching platform based on online social space

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International Journal of Computational Systems Engineering 2024年第3-4期8卷 229-237页

作者： Zhang, Xiaomei Marxist Academy Henan Polytechnic Institute Nanyang473000 China

To recommend learning resources that are suitable for students’ learning development, a content recommendation algorithm and KRCF algorithm are proposed based on the relationship between students and knowledge resources, as well as knowledge similarity user groups, to correct and predict students’ learning paths, and to establish a university teaching collaboration platform. The experimental results show that the KRCF algorithm performs better than algorithms such as the CF algorithm. Under different iterations or training set ratios, its RSME and MAE values are the smallest. When the training set ratio is 0.15, its MAE value is 0.72, which is lower than the MCS-CF algorithm. Overall, the accuracy of the KRCF algorithm is over 70%, with an accuracy of 94.67% when there are 50 neighbours. The accuracy of content recommendation algorithms in recommending learning resources is high, and personalised systems can quickly respond to user requests. Copyright © 2024 Inderscience Enterprises Ltd.

关键词： consensus algorithm

Density-Sensitive algorithms for (∆ + 1)-Edge Coloring

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arXiv 2023年

作者： Bhattacharya, Sayan Costa, Martín Panski, Nadav Solomon, Shay University of Warwick United Kingdom Tel Aviv University Israel

Vizing's theorem asserts the existence of a (∆ + 1)-edge coloring for any graph G, where ∆ = ∆(G) denotes the maximum degree of G. Several polynomial time (∆ + 1)-edge coloring algorithms are known, and the state-of-the-art running time (up to polylogarithmic factors) is Õ(min{m√n,m∆}),1 by Gabow, Nishizeki, Kariv, Leven and Terada from 1985, where n and m denote the number of vertices and edges in the graph, respectively. Recently, Sinnamon shaved off a polylog(n) factor from the time bound of Gabow et al. The arboricity α = α(G) of a graph G is the minimum number of edge-disjoint forests into which its edge set can be partitioned, and it is a measure of the graph's "uniform density". While α ≤ ∆ in any graph, many natural and real-world graphs exhibit a significant separation between α and ∆. In this work we design a (∆+1)-edge coloring algorithm with a running time of (Equation presented), thus improving the longstanding time barrier by a factor of (Equation presented). In particular, we achieve a near-linear runtime for bounded arboricity graphs (i.e., α = Õ(1)) as well as when (Equation presented). Our algorithm builds on Gabow et al.'s and Sinnamon's algorithms, and can be viewed as a density-sensitive refinement of them. © 2023, CC BY.

关键词： consensus algorithm

Efficient Graph Matching for Correlated Stochastic Block Models

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arXiv 2024年

作者： Chai, Shuwen Rácz, Miklós Z. Department of Computer Science Northwestern University United States Department of Statistics and Data Science Department of Computer Science Northwestern University United States

We study learning problems on correlated stochastic block models with two balanced communities. Our main result gives the first efficient algorithm for graph matching in this setting. In the most interesting regime where the average degree is logarithmic in the number of vertices, this algorithm correctly matches all but a vanishing fraction of vertices with high probability, whenever the edge correlation parameter s satisfies s2 > α ≈ 0.338, where α is Otter’s tree-counting constant. Moreover, we extend this to an efficient algorithm for exact graph matching whenever this is information-theoretically possible, positively resolving an open problem of Rácz and Sridhar (NeurIPS 2021). Our algorithm generalizes the recent breakthrough work of Mao, Wu, Xu, and Yu (STOC 2023), which is based on centered subgraph counts of a large family of trees termed chandeliers. A major technical challenge that we overcome is dealing with the additional estimation errors that are necessarily present due to the fact that, in relevant parameter regimes, the latent community partition cannot be exactly recovered from a single graph. As an application of our results, we give an efficient algorithm for exact community recovery using multiple correlated graphs in parameter regimes where it is information-theoretically impossible to do so using just a single graph. © 2024, CC BY.

关键词： consensus algorithm