Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing最新文献_第5页

On the Complexity of Distributed Splitting Problems 关于分布式分裂问题的复杂性

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-28 DOI: 10.1145/3293611.3331630

P. Bamberger, M. Ghaffari, F. Kuhn, Yannic Maus, Jara Uitto

{"title":"On the Complexity of Distributed Splitting Problems","authors":"P. Bamberger, M. Ghaffari, F. Kuhn, Yannic Maus, Jara Uitto","doi":"10.1145/3293611.3331630","DOIUrl":"https://doi.org/10.1145/3293611.3331630","url":null,"abstract":"One of the fundamental open problems in the area of distributed graph algorithms is whether randomization is needed for efficient symmetry breaking. While there are poly log n-time randomized algorithms for all the classic symmetry breaking problems, for many of them, the best deterministic algorithms are almost exponentially slower. The following basic local splitting problem, which is known as weak splitting, takes a central role in this context: Each node of a graph G=(V,E) has to be colored red or blue such that each node of sufficiently large degree has at least one neighbor of each color. Ghaffari, Kuhn, and Maus [STOC '17] showed that this seemingly simple problem is complete w.r.t. the above fundamental open question in the following sense: If there is an efficient poly log n-time determinstic distributed algorithm for weak splitting, then there is such an algorithm for all locally checkable graph problems for which an efficient randomized algorithm exists. We investigate the distributed complexity of weak splitting and some closely related problems and we in particular obtain the following results: We obtain efficient algorithms for special cases of weak splitting in nearly regular graphs. We show that if δ=Ø(log n) and Δ are the minimum and maximum degrees of G, weak splitting can be solved deterministically in time O #916;(√ over δ • poly(log n)). Further, if δ = Ø(log log n) and Δ ≤ 2ε δ, the time complexity is O(Δ over δ⋅poly(log log n)). We prove that the following two related problems are also complete in the same sense: (I) Color the nodes of a graph with C ≤ poly log n colors such that each node with a sufficiently large polylogarithmic degree has at least 2 log n different colors among its neighbors, and (II) Color the nodes with a large constant number of colors so that for each node of a sufficiently large at least logarithmic degree d(v), the number of neighbors of each color is at most (1-εd(v) for some constant ε > 0.","PeriodicalId":153766,"journal":{"name":"Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124865845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Improved Distributed Approximations for Minimum-Weight Two-Edge-Connected Spanning Subgraph 最小权值两边连通生成子图的改进分布逼近

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-26 DOI: 10.1145/3293611.3331617

Michal Dory, M. Ghaffari

{"title":"Improved Distributed Approximations for Minimum-Weight Two-Edge-Connected Spanning Subgraph","authors":"Michal Dory, M. Ghaffari","doi":"10.1145/3293611.3331617","DOIUrl":"https://doi.org/10.1145/3293611.3331617","url":null,"abstract":"The minimum-weight 2-edge-connected spanning subgraph (2-ECSS) problem is a natural generalization of the well-studied minimum-weight spanning tree (MST) problem, and it has received considerable attention in the area of network design. The latter problem asks for a minimum-weight subgraph with an edge connectivity of 1 between each pair of vertices while the former strengthens this edge-connectivity requirement to 2. Despite this resemblance, the 2-ECSS problem is considerably more complex than MST. While MST admits a linear-time centralized exact algorithm, 2-ECSS is NP-hard and the best known centralized approximation algorithm for it (that runs in polynomial time) gives a 2-approximation. In this paper, we give a deterministic distributed algorithm with round complexity of Õ (D + √n) that computes a (9 + ε)-approximation of 2-ECSS, for any constant ε > 0. Up to logarithmic factors, this complexity matches the Ø (D + √ n) lower bound that can be derived from the technique of Das Sarma et al. [STOC'11], as shown by Censor-Hillel and Dory [OPODIS'17]. Our result is the first distributed constant approximation for 2-ECSS in the nearly optimal time and it improves on a recent randomized algorithm of Dory [PODC'18], which achieved an O(łog n)-approximation in Õ (D+√ ) rounds. We also present an alternative algorithm for O(log n)-approximation, whose round complexity is linear in the low-congestion shortcut parameter of the network---following a framework introduced by Ghaffari and Haeupler [SODA'16]. This algorithm has round complexity Ö (D+√n) in worst-case networks but it provably runs much faster in many well-behaved graph families of interest. For instance, it runs in Õ (D) time in planar networks and those with bounded genus, bounded path-width or bounded tree-width.","PeriodicalId":153766,"journal":{"name":"Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124333003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16

On the Parallels between Paxos and Raft, and how to Port Optimizations Paxos和Raft的相似之处，以及如何移植优化

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-26 DOI: 10.1145/3293611.3331595

Zhaoguo Wang, Changgeng Zhao, Shuai Mu, Haibo Chen, Jinyang Li

引用次数: 15

Deterministic Distributed Dominating Set Approximation in the CONGEST Model CONGEST模型中的确定性分布支配集近似

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-26 DOI: 10.1145/3293611.3331626

Janosch Deurer, F. Kuhn, Yannic Maus

引用次数: 24

Hardness of Distributed Optimization 分布优化的难度

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-24 DOI: 10.1145/3293611.3331597

Nir Bachrach, K. Censor-Hillel, Michal Dory, Yuval Efron, Dean Leitersdorf, A. Paz

{"title":"Hardness of Distributed Optimization","authors":"Nir Bachrach, K. Censor-Hillel, Michal Dory, Yuval Efron, Dean Leitersdorf, A. Paz","doi":"10.1145/3293611.3331597","DOIUrl":"https://doi.org/10.1145/3293611.3331597","url":null,"abstract":"This paper studies lower bounds for fundamental optimization problems in the CONGEST model. We show that solving problems exactly in this model can be a hard task, by providing tildeΩmega (n2) lower bounds for cornerstone problems, such as minimum dominating set (MDS), Hamiltonian path, Steiner tree and max-cut. These are almost tight, since all of these problems can be solved optimally in O(n2) rounds. Moreover, we show that even in bounded-degree graphs and even in simple graphs with maximum degree 5 and logarithmic diameter, it holds that various tasks, such as finding a maximum independent set (MaxIS) or a minimum vertex cover, are still difficult, requiring a near-tight number of tildeΩ (n) rounds. Furthermore, we show that in some cases even approximations are difficult, by providing an tildeΩ (n2) lower bound for a (7/8+ε)-approximation for MaxIS, and a nearly-linear lower bound for an O(log n )-approximation for the k-MDS problem for any constant k geq≥ 2, as well as for several variants of the Steiner tree problem. Our lower bounds are based on a rich variety of constructions that leverage novel observations, and reductions among problems that are specialized for the CONGEST model. However, for several additional approximation problems, as well as for exact computation of some central problems in P, such as maximum matching and max flow, we show that such constructions cannot be designed, by which we exemplify some limitations of this framework.","PeriodicalId":153766,"journal":{"name":"Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing","volume":"543 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132731646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36

Topological Characterization of Consensus under General Message Adversaries 通用消息对抗下共识的拓扑表征

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-23 DOI: 10.1145/3293611.3331624

Thomas Nowak, U. Schmid, Kyrill Winkler

{"title":"Topological Characterization of Consensus under General Message Adversaries","authors":"Thomas Nowak, U. Schmid, Kyrill Winkler","doi":"10.1145/3293611.3331624","DOIUrl":"https://doi.org/10.1145/3293611.3331624","url":null,"abstract":"In this paper, we provide a rigorous characterization of consensus solvability in synchronous directed dynamic networks controlled by an arbitrary message adversary using point-set topology: We extend the approach introduced by Alpern and Schneider in 1985 by introducing two novel topologies on the space of infinite executions: the process-view topology, induced by a distance function that relies on the local view of a given process in an execution, and the minimum topology, which is induced by a distance function that focuses on the local view of the process that is the last to distinguish two executions. We establish some simple but powerful topological results, which not only lead to a topological explanation of bivalence arguments, but also provide necessary and sufficient topological conditions on the admissible graph sequences of a message adversary for solving consensus. In particular, we characterize consensus solvability in terms of connectivity of the set of admissible graph sequences. For non-compact message adversaries, which are not limit-closed in the sense that there is a convergent sequence of graph sequences whose limit is not permitted, this requires the exclusion of all \"fair'' and \"unfair'' limit sequences that coincide with the forever bivalent runs constructed in bivalence proofs. For both compact and non-compact message adversaries, we also provide tailored characterizations of consensus solvability, i.e., tight conditions for impossibility and existence of algorithms, based on the broadcastability of the connected components of the set of admissible graph sequences.","PeriodicalId":153766,"journal":{"name":"Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121143877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 25

Connectivity Lower Bounds in Broadcast Congested Clique 广播拥塞团的连通性下限

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-22 DOI: 10.1145/3293611.3331569

Shreyas Pai, S. Pemmaraju

{"title":"Connectivity Lower Bounds in Broadcast Congested Clique","authors":"Shreyas Pai, S. Pemmaraju","doi":"10.1145/3293611.3331569","DOIUrl":"https://doi.org/10.1145/3293611.3331569","url":null,"abstract":"We prove three new lower bounds for graph connectivity in the 1-bit broadcast congested clique model, BCC(1). First, in the KT-0 version of BCC(1), in which nodes are aware of neighbors only through port numbers, we show an Ømega(log n) round lower bound for CONNECTIVITY even for constant-error randomized Monte Carlo algorithms. The deterministic version of this result can be obtained via the well-known \"edge-crossing\" argument, but, the randomized version of this result requires establishing new combinatorial results regarding the indistinguishability graph induced by inputs. In our second result, we show that the Ømega(log n) lower bound result extends to the KT-1 version of the BCC(1) model, in which nodes are aware of IDs of all neighbors, though our proof works only for deterministic algorithms. Since nodes know IDs of their neighbors in the KT-1 model, it is no longer possible to play \"edge-crossing\" tricks; instead we present a reduction from the 2-party communication complexity problem PARTITION in which Alice and Bob are give two set partitions on [n] and are required to determine if the join of these two set partitions equals the trivial one-part set partition. While our KT-1 CONNECTIVITY lower bound holds only for deterministic algorithms, in our third result we extend this Ømega(log n) KT-1 lower bound to constant-error Monte Carlo algorithms for the closely related CONNECTED COMPONENTS problem. We use information-theoretic techniques to obtain this result. All our results hold for the seemingly easy special case of CONNECTIVITY in which an algorithm has to distinguish an instance with one cycle from an instance with multiple cycles. Our results showcase three rather different lower bound techniques and lay the groundwork for further improvements in lower bounds for CONNECTIVITY in the BCC(1) model.","PeriodicalId":153766,"journal":{"name":"Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing","volume":"27 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113958163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Linearizable State Machine Replication of State-Based CRDTs without Logs 基于状态的无日志crdt的线性状态机复制

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-21 DOI: 10.1145/3293611.3331568

Jan Skrzypczak, F. Schintke, T. Schütt

{"title":"Linearizable State Machine Replication of State-Based CRDTs without Logs","authors":"Jan Skrzypczak, F. Schintke, T. Schütt","doi":"10.1145/3293611.3331568","DOIUrl":"https://doi.org/10.1145/3293611.3331568","url":null,"abstract":"General solutions of state machine replication have to ensure that all replicas apply the same commands in the same order, even in the presence of failures. Such strict ordering incurs high synchronization costs due to the use of distributed consensus or a leader. This paper presents a protocol for linearizable state machine replication of conflict-free replicated data types (CRDTs) that neither requires consensus nor a leader. By leveraging the properties of state-based CRDTs---in particular the monotonic growth of a join semilattice---synchronization overhead is greatly reduced. In addition, updates just need a single round trip and modify the state 'in-place' without the need for a log. Furthermore, the message size overhead for coordination consists of a single counter per message. While reads in the presence of concurrent updates are not wait-free without a coordinator, we show that more than 97,% of reads can be handled in one or two round trips under highly concurrent accesses. Our protocol achieves high throughput without auxiliary processes such as command log management or leader election. It is well suited for all practical scenarios that need linearizable access on CRDT data on a fine-granular scale.","PeriodicalId":153766,"journal":{"name":"Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing","volume":"197 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121562177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 14

Hyaline: Fast and Transparent Lock-Free Memory Reclamation 透明:快速和透明的无锁内存回收

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-20 DOI: 10.1145/3293611.3331575

R. Nikolaev, B. Ravindran

引用次数: 14

Broadcast Congested Clique: Planted Cliques and Pseudorandom Generators 广播拥挤的集团:种植集团和伪随机发生器

Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing Pub Date : 2019-05-19 DOI: 10.1145/3293611.3331599

Lijie Chen, O. Grossman

{"title":"Broadcast Congested Clique: Planted Cliques and Pseudorandom Generators","authors":"Lijie Chen, O. Grossman","doi":"10.1145/3293611.3331599","DOIUrl":"https://doi.org/10.1145/3293611.3331599","url":null,"abstract":"We develop techniques to prove lower bounds for the BCAST(log n) Broadcast Congested Clique model (a distributed message passing model where in each round, each processor can broadcast an O(log n)-sized message to all other processors). Our techniques are built to prove bounds for natural input distributions. So far, all lower bounds for problems in the model relied on constructing specifically tailored graph families for the specific problem at hand, resulting in lower bounds for artificially constructed inputs, instead of natural input distributions. One of our results is a lower bound for the directed planted clique problem. In this problem, an input graph is either a random directed graph (each directed edge is included with probability 1/2), or a random graph with a planted clique of size k. That is, k randomly chosen vertices have all of the edges between them included, and all other edges in the graph appear with probability 1/2. The goal is to determine whether a clique exists. We show that when k = n(1/4 - ε), this problem requires a number of rounds polynomial in n. Additionally, we construct a pseudo-random generator which fools the Broadcast Congested Clique. This allows us to show that every k round randomized algorithm in which each processor uses up to n random bits can be efficiently transformed into an O(k)-round randomized algorithm in which each processor uses only up to O(k log n) random bits, while maintaining a high success probability. The pseudo-random generator is simple to describe, computationally very cheap, and its seed size is optimal up to constant factors. However, the analysis is quite involved, and is based on the new technique for proving lower bounds in the model. The technique also allows us to prove the first average case lower bound for the Broadcast Congested Clique, as well as an average-case time hierarchy. We hope our technique will lead to more lower bounds for problems such as triangle counting, APSP, MST, diameter, and more, for natural input distributions.","PeriodicalId":153766,"journal":{"name":"Proceedings of the 2019 ACM Symposium on Principles of Distributed Computing","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127061986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4