Proceedings of the ACM Symposium on Principles of Distributed Computing最新文献

{"title":"Distributed MIS via All-to-All Communication","authors":"M. Ghaffari","doi":"10.1145/3087801.3087830","DOIUrl":"https://doi.org/10.1145/3087801.3087830","url":null,"abstract":"Computing a Maximal Independent Set (MIS) is a central problem in distributed graph algorithms. This paper presents an improved randomized distributed algorithm for congested clique model, defined as follows: Given a graph G=(V, E), initially each node knows only its neighbors. Communication happens in synchronous rounds over a complete graph, and per round each node can send O(log n) bits to each other node. We present a randomized algorithm that computes an MIS in Õ((log Δ)/(√(log n)) + 1 ) ≤ Õ(√(log Δ)) rounds of congested clique, with high probability. Here Δ denotes the maximum degree in the graph. This improves quadratically on the O(log Δ) algorithm of [Ghaffari, SODA'16]. The core technical novelty in this result is a certain local sparsification technique for MIS, which we believe to be of independent interest.","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122059379","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}

{"title":"Clocked Population Protocols","authors":"J. Aspnes","doi":"10.1145/3087801.3087836","DOIUrl":"https://doi.org/10.1145/3087801.3087836","url":null,"abstract":"Population protocols are required to converge to the correct answer, and are subject to a fairness condition that guarantees eventual progress, but generally have no internal mechanism for detecting when this progress has occurred. We define an extension to the standard population protocol that provides each agent with a clock signal that indicates when the agent has waited long enough. To simplify the model, we represent \"long enough\" as an infinite time interval, and treat a clocked population protocol as operating over transfinite time. This gives a clean theoretical model that we show how to translate back into finite real-world executions where the clock ticks whenever the underlying protocol is looping or stuck. Over finite time intervals, the protocol behaves as in the standard model. At nonzero limit ordinals ω, ω2, etc., corresponding to clock ticks, the protocol switches to a limit of previous configurations supplemented by an signal registering in an extra component in some of the agents' states. Using transfinite times means that we can represent fairness over sequences of transitions that may include clock ticks with the same definition as over smaller intervals. Using arbitrary ordinals allows using times like ω2 or ω3 to represent convergence that depends on detecting convergence repeatedly at lower levels. We show that a clocked population protocol running in less than ωk time for any fixed k ≥ 2 is equivalent in power to a nondeterministic Turing machine with space complexity logarithmic in the size of the population. A consequence of this equivalence is that any symmetric predicate that can be computed in less than ωk time can be computed in less than ω2 time, which requires only finitely many clock ticks.","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117117962","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}

{"title":"Symmetry Breaking with Noisy Processes","authors":"Seth Gilbert, Calvin C. Newport","doi":"10.1145/3087801.3087814","DOIUrl":"https://doi.org/10.1145/3087801.3087814","url":null,"abstract":"Biology and computer science intersect at the problem of symmetry breaking, which is relevant in both fields. Accordingly, in recent years, distributed algorithm theorists have studied symmetry breaking problems in models inspired by biology to help provide insight into the capabilities and constraints of this natural process. A potential shortcoming of these models, however, is that they execute distributed algorithms precisely as specified. In nature, where computation is often implemented by messy analog systems, this precision cannot necessarily be guaranteed. Motivated by this observation, in this paper we present a general method for injecting computational noise into any distributed system model that describes processes as interacting state machines. Our method captures noise as a force that can cause state machines to transition to the wrong state. We combine this formalization of noise with the beeping models that have been a popular target of recent work on bio-inspired symmetry breaking. We produce new upper and lower bounds for both single hop and multihop models---studying leader election in the former and the maximal independent set problem in the latter. These bounds introduce new techniques for achieving robustness to noise, and identify some fundamental limits in this pursuit. We argue that both our general approach and specific results can help advance the productive relationship between biology and algorithm theory.","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129124587","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}

{"title":"Brief Announcement: Statement Voting and Liquid Democracy","authors":"Bingsheng Zhang, Hong-Sheng Zhou","doi":"10.1145/3087801.3087868","DOIUrl":"https://doi.org/10.1145/3087801.3087868","url":null,"abstract":"The existing (election) voting systems, e.g., representative democracy, have many limitations and often fail to serve the best interest of the people in collective decision making. To address this issue, the concept of liquid democracy has been emerging as an alternative decision-making model to make better use of \"the wisdom of crowds\". Very recently, a few liquid democracy implementations, e.g. Google Votes and Decentralized Autonomous Organization (DAO), are released; however, those systems only focus on the functionality aspect, as no privacy/anonymity is considered. In this work, we, for the first time, provide a rigorous study of liquid democracy under the Universal Composability (UC) frame- work. In the literature, liquid democracy was achieved via two separate stages -- delegation and voting. We propose an efficient liquid democracy e-voting scheme that uni es these two stages. At the core of our design is a new voting concept called statement voting, which can be viewed as a natural extension of the conventional voting approaches. We remark that our statement voting can be extended to enable more complex voting and generic ledger-based non-interactive multi-party computation. We believe that the statement voting concept opens a door for constructing a new class of e-voting schemes.","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122372513","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}

{"title":"Session details: Session 7","authors":"L. Alvisi","doi":"10.1145/3252879","DOIUrl":"https://doi.org/10.1145/3252879","url":null,"abstract":"","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"256 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116480767","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}

{"title":"Brief Announcement: Gossiping with Latencies","authors":"Seth Gilbert, Peter Robinson, S. Sourav","doi":"10.1145/3087801.3087846","DOIUrl":"https://doi.org/10.1145/3087801.3087846","url":null,"abstract":"Consider the classical problem of information dissemination: one (or more) nodes in a network have some information that they want to distribute to the remainder of the network. In this paper, we study the cost of information dissemination in networks where edges have latencies, i.e., sending a message from one node to another takes some amount of time. We first generalize the idea of conductance to weighted graphs, defining φ* to be the \"weighted conductance\" and l* to be the \"critical latency.\" One goal of this paper is to argue that φ* characterizes the connectivity of a weighted graph with latencies in much the same way that conductance characterizes the connectivity of unweighted graphs. We give near tight lower and upper bounds on the problem of information dissemination. Specifically, we show that in a graph with (weighted) diameter D (with latencies as weights), maximum degree Δ, weighted conductance φ* and critical latency l*, any information dissemination algorithm requires at least Ω(min(D+Δ, l*/φ*)) time. We then give nearly matching algorithms, showing that information dissemination can be solved in O(min((D + Δ)log3n), (l*/φ*)log(n)) time.","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"177 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116847965","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}

{"title":"Session details: Session 3","authors":"K. Konwar","doi":"10.1145/3252875","DOIUrl":"https://doi.org/10.1145/3252875","url":null,"abstract":"","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114569573","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}

{"title":"Session details: Session 2","authors":"Faith Ellen","doi":"10.1145/3252874","DOIUrl":"https://doi.org/10.1145/3252874","url":null,"abstract":"","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127965538","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}

{"title":"Asynchronous Shared Channel","authors":"G. D. Marco, Grzegorz Stachowiak","doi":"10.1145/3087801.3087831","DOIUrl":"https://doi.org/10.1145/3087801.3087831","url":null,"abstract":"In this work we address the question whether a simple shared channel could be efficiently utilized, that is, with a constant throughput and linear packet latency. A shared channel (also called a multiple access channel), introduced nearly 50 years ago in the context of the Ethernet [36], is among the most popular and widely studied models of communication and distributed computing. In a nutshell, a number of stations is able to communicate by transmitting and listening to a shared channel, and a message is successfully delivered to all stations if and only if its source station is the only transmitter at a time. Despite of a vast amount of work in the last decades, many fundamental questions remain open, such as: What is the impact of asynchrony on channel utilization? How important is the knowledge/estimate of the number of contenders? Could non-adaptive protocols (i.e., random codes) be asymptotically as efficient as adaptive protocols? In this work we present a broad picture of results answering the above mentioned questions for a fundamental problem of contention resolution, in which each of the contending stations needs to broadcast successfully its message. We show that adaptive algorithms or algorithms with the knowledge of contention size k (i.e., random codes with knowledge of k) achieve constant channel throughput and linear message latency even for very weak channels, i.e., with feedback restricted to simple acknowledgments and in the absence of synchronization. This asymptotically optimal performance cannot be extended to other settings --- we prove that there is no non-adaptive algorithm without the knowledge of contention size k achieving throughput omega((loglog k)^2/(log k)) and/or admitting latency o(klog k/(loglog k)^2). This means, in particular, that coding (even random) with acknowledgments is not very efficient on a shared channel without synchronization or estimate of contention size. We also present a non-adaptive algorithm with no knowledge of contention size that almost matches these two complexities. More specifically, it achieves latency O(klog^2 k) and channel utilization Omega(1/log^2 k) even if stations do not switch off after successful transmissions (and thus, could disturb other stations in succeeding), and could be improved by factor Theta(loglog k) if stations switch off after acknowledgment. Despite the absense of a collision detection mechanism, our algorithms are also efficient in terms of energy. The maximum number of channel accesses (including transmissions and listenings) for our non-adaptive solutions, with and without knowledge of k, is respectively O(log k) and O(log^2 k) whp. Regarding the adaptive algorithm, we argue that a simple modification of our protocol preserves constant throughput and linear latency while achieving O(log k) maximum number of channel accesses per station whp.","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121893956","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}

{"title":"Session details: Session 4","authors":"Calvin C. Newport","doi":"10.1145/3252876","DOIUrl":"https://doi.org/10.1145/3252876","url":null,"abstract":"","PeriodicalId":324970,"journal":{"name":"Proceedings of the ACM Symposium on Principles of Distributed Computing","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121093851","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}