Scalable distributed systems face inherent trade-offs arising from the relatively high cost of exchanging information between computing nodes. Brewer's CAP (Consistency, Availability, Partition-Tolerance) principle states that when communication becomes impossible between isolated parts of the system (i.e., the network is partitioned), then the system must give up either safety (i.e., sometimes return an incorrect result) or liveness (i.e., sometimes fail to produce a result). Abadi generalized Brewer's principle by defining the PACELC (if Partition then Availability or Consistency, Else Latency or Consistency) formulation, which captures the ob- servation that the trade-off between safety and liveness is often made in practice even while the network is reliable. Building on Gilbert and Lynch's formal proof of the CAP principle, this paper presents a formal treatment of Abadi's formulation and connects this result to a body of prior work on latency bounds for distributed objects.
{"title":"Proving PACELC","authors":"W. Golab","doi":"10.1145/3197406.3197420","DOIUrl":"https://doi.org/10.1145/3197406.3197420","url":null,"abstract":"Scalable distributed systems face inherent trade-offs arising from the relatively high cost of exchanging information between computing nodes. Brewer's CAP (Consistency, Availability, Partition-Tolerance) principle states that when communication becomes impossible between isolated parts of the system (i.e., the network is partitioned), then the system must give up either safety (i.e., sometimes return an incorrect result) or liveness (i.e., sometimes fail to produce a result). Abadi generalized Brewer's principle by defining the PACELC (if Partition then Availability or Consistency, Else Latency or Consistency) formulation, which captures the ob- servation that the trade-off between safety and liveness is often made in practice even while the network is reliable. Building on Gilbert and Lynch's formal proof of the CAP principle, this paper presents a formal treatment of Abadi's formulation and connects this result to a body of prior work on latency bounds for distributed objects.","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78753372","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}
Abstract argumentation frameworks introduced by Dung [Dun95] are a formal way of representing discussions de ned through arguments and a binary attack relation between them. In dynamic settings there is a need to allow for uncertainty in such argumentation frameworks, hence attack-incomplete and argument-incomplete argumentation frameworks are considered as well. Different semantics are de ned in order to identify a set of acceptable arguments, and the verification problem asks whether some given set is an extension for a given semantics. This survey gives an overview of the complexity of the verification problem for different semantics in complete and incomplete argumentation frameworks.
{"title":"Guest Column: Complexity of Verication in Abstract Argumentation Frameworks","authors":"Dorothea Baumeister","doi":"10.1145/3173127.3173137","DOIUrl":"https://doi.org/10.1145/3173127.3173137","url":null,"abstract":"Abstract argumentation frameworks introduced by Dung [Dun95] are a formal way of representing discussions de ned through arguments and a binary attack relation between them. In dynamic settings there is a need to allow for uncertainty in such argumentation frameworks, hence attack-incomplete and argument-incomplete argumentation frameworks are considered as well. Different semantics are de ned in order to identify a set of acceptable arguments, and the verification problem asks whether some given set is an extension for a given semantics. This survey gives an overview of the complexity of the verification problem for different semantics in complete and incomplete argumentation frameworks.","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84520630","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}
The 31st International Symposium on Distributed Computing, DISC 2017, was held on October 16-20, 2017, in Vienna, Austria. The main conference took place at the Austria Trend Hotel Park Royal Palace close to the Schönbrunn Castle. Many of the attendees claimed that they had not been to Vienna before, and, besides the conference events, also enjoyed visiting the city. However, attendance at all talks and the six (!) colocated workshops was very high. Many will remember this conference also for the great sweets and cakes that were served; there was probably no single person who did not go through some kind of a sugar shock. This review contains a few selected events and talks which constitute our personal highlights of the conference.
{"title":"DISC 2017 Review","authors":"Manuela Fischer, Yannic Maus","doi":"10.1145/3173127.3173144","DOIUrl":"https://doi.org/10.1145/3173127.3173144","url":null,"abstract":"The 31st International Symposium on Distributed Computing, DISC 2017, was held on October 16-20, 2017, in Vienna, Austria. The main conference took place at the Austria Trend Hotel Park Royal Palace close to the Schönbrunn Castle. Many of the attendees claimed that they had not been to Vienna before, and, besides the conference events, also enjoyed visiting the city. However, attendance at all talks and the six (!) colocated workshops was very high. Many will remember this conference also for the great sweets and cakes that were served; there was probably no single person who did not go through some kind of a sugar shock. This review contains a few selected events and talks which constitute our personal highlights of the conference.","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79719869","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":"Review of Communication Networks: An Optimization, Control, and Stochastic Networks Perspective R. Srikant and L. Ying","authors":"V. Liberatore","doi":"10.1145/3173127.3173130","DOIUrl":"https://doi.org/10.1145/3173127.3173130","url":null,"abstract":"","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89141019","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}
The list update problem is a well studied online problem in the area of self-adjusting data structures. Understanding the o?ine version of this problem is crucial because of the role it plays in the competitive analysis of online list update algorithms. In this paper we settle a long-standing open problem by showing that the o?ine list update problem is NP-hard.
{"title":"Computational Geometry Column 66","authors":"Khaled M. Elbassioni, A. Dumitrescu","doi":"10.1145/3173127.3173138","DOIUrl":"https://doi.org/10.1145/3173127.3173138","url":null,"abstract":"The list update problem is a well studied online problem in the area of self-adjusting data structures. Understanding the o?ine version of this problem is crucial because of the role it plays in the competitive analysis of online list update algorithms. In this paper we settle a long-standing open problem by showing that the o?ine list update problem is NP-hard.","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75229494","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}
As with prior December issues, this issue is devoted to a review of notable events related to distributed computing that occurred during the year. First, congratulations to Elizabeth Borowksy and Eli Gafni, winners of the 2017 Edsger W. Dijkstra Prize in Distributed Computing for their paper “Generalized FLP Impossibility Result for t-Resilient Computations”! Their paper appeared in the 1993 ACM Symposium on Theory of Computing (STOC). The prize is jointly sponsored by ACM and EATCS, and is given alternately at PODC1 and DISC2; this year it was given at DISC. To quote from the award committee’s citation,
与12月份的前几期一样，这一期致力于回顾这一年中发生的与分布式计算相关的重大事件。首先，祝贺Elizabeth Borowksy和Eli Gafni, 2017年Edsger W. Dijkstra分布式计算奖的获得者，他们的论文“t-弹性计算的广义FLP不可能结果”!他们的论文发表在1993年ACM计算理论研讨会(STOC)上。该奖项由ACM和EATCS联合主办，在PODC1和DISC2上轮流颁发;今年是在DISC上颁发的。引用评委会的评语，
{"title":"Distributed Computing Column 68","authors":"J. Welch","doi":"10.1145/3173127.3173140","DOIUrl":"https://doi.org/10.1145/3173127.3173140","url":null,"abstract":"As with prior December issues, this issue is devoted to a review of notable events related to distributed computing that occurred during the year. First, congratulations to Elizabeth Borowksy and Eli Gafni, winners of the 2017 Edsger W. Dijkstra Prize in Distributed Computing for their paper “Generalized FLP Impossibility Result for t-Resilient Computations”! Their paper appeared in the 1993 ACM Symposium on Theory of Computing (STOC). The prize is jointly sponsored by ACM and EATCS, and is given alternately at PODC1 and DISC2; this year it was given at DISC. To quote from the award committee’s citation,","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88875887","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}
This issue should reach your hands or screen in December 2017, as the new year approaches. Perhaps you are wondering how to best spend 2018? Along those lines, a quote comes to mind from the 1990s animated television series “Pinky and the Brain,” which was executive produced by Steven Spielberg and is about two lab mice. There was a running joke on the series, and that joke generally went like this (I’m lifting the wording from Wikiquote.org to get it right):
随着新年的临近，这个问题应该会在2017年12月出现在你的手中或屏幕上。也许你想知道如何度过2018年?说到这里，我想起了上世纪90年代的动画电视连续剧《小指与大脑》(Pinky and the Brain)中的一句话，该片由史蒂文·斯皮尔伯格(Steven Spielberg)执行制作，讲述了两只实验室老鼠的故事。在这个系列中有一个流传的笑话，这个笑话通常是这样的(我从Wikiquote.org上摘取了措辞，以确保正确):
{"title":"SIGACT News Complexity Theory Column 96","authors":"L. Hemaspaandra","doi":"10.1145/3173127.3173136","DOIUrl":"https://doi.org/10.1145/3173127.3173136","url":null,"abstract":"This issue should reach your hands or screen in December 2017, as the new year approaches. Perhaps you are wondering how to best spend 2018? Along those lines, a quote comes to mind from the 1990s animated television series “Pinky and the Brain,” which was executive produced by Steven Spielberg and is about two lab mice. There was a running joke on the series, and that joke generally went like this (I’m lifting the wording from Wikiquote.org to get it right):","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79956100","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}
Social choice theory is an area of economics that studies collective decision making. It provides mathematical models and guidelines for making the right choices. Examples of collective decision making include sharing a cake among friends and voting in an election. Computational social choice is a discipline which may be considered to be at the crossroads of economics and computer science. This handbook on computational social choice deals with the computational aspects of collective decision making. It contains contributions from thirty-six eminent researchers in the field of computational social choice. The key areas covered by the book are voting, fair allocation of divisible as well as indivisible goods, coalition formation, and miscellaneous topics such as judgement aggregation and knockout tournaments. The book is available in hardcover and Adobe eBook Reader formats. The ISBNs are 9781107060432 (hardcover) and 9781316490631 (ebook). They are priced at US $59.99 and US $48, respectively.
{"title":"Review of Handbook of Computational Social Choice Edited by Felix Brandt, Vincent Conitzer, Ulle Endriss, Jérôme Lang, and Ariel D. Procaccia","authors":"S. Nagaraj","doi":"10.1145/3173127.3173131","DOIUrl":"https://doi.org/10.1145/3173127.3173131","url":null,"abstract":"Social choice theory is an area of economics that studies collective decision making. It provides mathematical models and guidelines for making the right choices. Examples of collective decision making include sharing a cake among friends and voting in an election. Computational social choice is a discipline which may be considered to be at the crossroads of economics and computer science. This handbook on computational social choice deals with the computational aspects of collective decision making. It contains contributions from thirty-six eminent researchers in the field of computational social choice. The key areas covered by the book are voting, fair allocation of divisible as well as indivisible goods, coalition formation, and miscellaneous topics such as judgement aggregation and knockout tournaments. The book is available in hardcover and Adobe eBook Reader formats. The ISBNs are 9781107060432 (hardcover) and 9781316490631 (ebook). They are priced at US $59.99 and US $48, respectively.","PeriodicalId":22106,"journal":{"name":"SIGACT News","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77062171","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}
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