V. Sreejith, K. Anupama, L. Gudino, R. Suriyadeepan
Connectivity restoration in Wireless Sensor Network (WSN) is a common problem and several solutions has been proposed in the literature. Reasons for partition include initial random deployment, node failure due to low battery life, hardware malfunction etc. This paper focuses on partition discovery and hence restoring connectivity in a segmented network using Mobile Relay (MR) nodes. We propose a hybrid of frontier-based and random-direction exploration approaches for detecting partitions in a given area. An approximation algorithm for Steiner point based minimum spanning tree is adopted to determine the topology for connecting the discovered partition. Optimal assignment of mobile relays in this topology is visualized as a Bottleneck Assignment Problem (BAP). Our approach guarantees use of minimum number of MR nodes to be placed in minimum time. Experimental results indicate that the proposed approach can be effectively used for connectivity restoration in a partitioned network.
{"title":"Partition Discovery and Connectivity Restoration in WSN using Mobile Relays","authors":"V. Sreejith, K. Anupama, L. Gudino, R. Suriyadeepan","doi":"10.1145/2684464.2684487","DOIUrl":"https://doi.org/10.1145/2684464.2684487","url":null,"abstract":"Connectivity restoration in Wireless Sensor Network (WSN) is a common problem and several solutions has been proposed in the literature. Reasons for partition include initial random deployment, node failure due to low battery life, hardware malfunction etc. This paper focuses on partition discovery and hence restoring connectivity in a segmented network using Mobile Relay (MR) nodes. We propose a hybrid of frontier-based and random-direction exploration approaches for detecting partitions in a given area. An approximation algorithm for Steiner point based minimum spanning tree is adopted to determine the topology for connecting the discovered partition. Optimal assignment of mobile relays in this topology is visualized as a Bottleneck Assignment Problem (BAP). Our approach guarantees use of minimum number of MR nodes to be placed in minimum time. Experimental results indicate that the proposed approach can be effectively used for connectivity restoration in a partitioned network.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134090285","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}
Delegation is a thread synchronization technique where access to shared data is performed through a dedicated server thread. When a client thread requires shared data access, it makes a request to a server and waits for a response. This paper studies delegation implementation over cache-coherent shared memory, with the goal of optimizing it for high throughput. Whereas client-server communication naturally fits message-passing systems, efficient implementation over cache-coherent shared memory requires careful optimization. We demonstrate optimizations that significantly improve delegation performance on two modern x86 processors (the Intel Xeon Westmere and the AMD Opteron Magny-Cours), enabling us to come up with counter, stack and queue implementations that outperform the best known alternatives in a large number of cases. Our optimized delegation solution achieves 1.4x (resp. 2x) higher throughput compared to the most efficient state-of-the-art delegation solution on the Intel Xeon (resp. AMD Opteron).
{"title":"On the Performance of Delegation over Cache-Coherent Shared Memory","authors":"Darko Petrovic, Thomas Ropars, A. Schiper","doi":"10.1145/2684464.2684476","DOIUrl":"https://doi.org/10.1145/2684464.2684476","url":null,"abstract":"Delegation is a thread synchronization technique where access to shared data is performed through a dedicated server thread. When a client thread requires shared data access, it makes a request to a server and waits for a response. This paper studies delegation implementation over cache-coherent shared memory, with the goal of optimizing it for high throughput. Whereas client-server communication naturally fits message-passing systems, efficient implementation over cache-coherent shared memory requires careful optimization. We demonstrate optimizations that significantly improve delegation performance on two modern x86 processors (the Intel Xeon Westmere and the AMD Opteron Magny-Cours), enabling us to come up with counter, stack and queue implementations that outperform the best known alternatives in a large number of cases. Our optimized delegation solution achieves 1.4x (resp. 2x) higher throughput compared to the most efficient state-of-the-art delegation solution on the Intel Xeon (resp. AMD Opteron).","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122205899","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}
Fabienne Carrier, A. Datta, Stéphane Devismes, L. Larmore
We consider the (deterministic) ℓ-exclusion problem, a generalization of the mutual exclusion problem which allows use of 1 ≤ ℓ < n identical copies of a non-sharable reusable resource among n processes, instead of only one, as standard mutual exclusion. This problem is defined using three properties: safety, fairness, and avoidance of ℓ-deadlock. We first show that any algorithm satisfying the three aforementioned properties has a waiting time of Ω(n − ℓ) rounds. Thus, when n is large, the gain (in terms of waiting time) of having ℓ copies of a resource, instead of one, becomes negligible. We propose to reformulate the problem by replacing the avoidance of ℓ-deadlock property by a new property, which we call fast waiting time, which requires waiting time of O(n/ℓ) rounds, which is asymptotically optimal. We call this new version of the problem fast waiting time ℓ-exclusion. We give two self-stabilizing solutions for this new problem. Our first solution works in oriented rooted ring networks. Our second solution is a generalization of the first, and works in every connected identified network.
{"title":"Self-Stabilizing ℓ-Exclusion Revisited","authors":"Fabienne Carrier, A. Datta, Stéphane Devismes, L. Larmore","doi":"10.1145/2684464.2684465","DOIUrl":"https://doi.org/10.1145/2684464.2684465","url":null,"abstract":"We consider the (deterministic) ℓ-exclusion problem, a generalization of the mutual exclusion problem which allows use of 1 ≤ ℓ < n identical copies of a non-sharable reusable resource among n processes, instead of only one, as standard mutual exclusion. This problem is defined using three properties: safety, fairness, and avoidance of ℓ-deadlock. We first show that any algorithm satisfying the three aforementioned properties has a waiting time of Ω(n − ℓ) rounds. Thus, when n is large, the gain (in terms of waiting time) of having ℓ copies of a resource, instead of one, becomes negligible. We propose to reformulate the problem by replacing the avoidance of ℓ-deadlock property by a new property, which we call fast waiting time, which requires waiting time of O(n/ℓ) rounds, which is asymptotically optimal. We call this new version of the problem fast waiting time ℓ-exclusion. We give two self-stabilizing solutions for this new problem. Our first solution works in oriented rooted ring networks. Our second solution is a generalization of the first, and works in every connected identified network.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114832088","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}
We present techniques for reducing false conflicts in distributed transactional data structure (DDS). The open nesting transactional model is the common solution because it allows nested transactions to commit independently of their parent transaction, thereby objects in the transaction read-set and write-set are released early, minimizing aborts due to false conflicts and improving concurrency. We present three protocols for avoiding false conflicts in DDS. Our first protocol, QR-ON, incorporates open nesting into the QR protocol that manages concurrency control for distributed transactional memory systems using quorum-based replication. We then introduce Optimistic Open Nesting, QR-OON, in which open-nested transactions commit asynchronously so that subsequent transactions can proceed without waiting for the commit of previous transactions. Finally, we propose an early release methodology, QR-ER, in which objects that do not affect the final state of the shared data are dropped from transaction's read-set, which avoids false conflicts and reduces communication costs. Our implementation and experimental studies revealed that QR-OON outperforms QR-ON by up to 43%, and that QR-ER outperforms QR-ON and QR-OON by up to 10X.
{"title":"On Reducing False Conflicts in Distributed Transactional Data Structures","authors":"A. Dhoke, R. Palmieri, B. Ravindran","doi":"10.1145/2684464.2684467","DOIUrl":"https://doi.org/10.1145/2684464.2684467","url":null,"abstract":"We present techniques for reducing false conflicts in distributed transactional data structure (DDS). The open nesting transactional model is the common solution because it allows nested transactions to commit independently of their parent transaction, thereby objects in the transaction read-set and write-set are released early, minimizing aborts due to false conflicts and improving concurrency. We present three protocols for avoiding false conflicts in DDS. Our first protocol, QR-ON, incorporates open nesting into the QR protocol that manages concurrency control for distributed transactional memory systems using quorum-based replication. We then introduce Optimistic Open Nesting, QR-OON, in which open-nested transactions commit asynchronously so that subsequent transactions can proceed without waiting for the commit of previous transactions. Finally, we propose an early release methodology, QR-ER, in which objects that do not affect the final state of the shared data are dropped from transaction's read-set, which avoids false conflicts and reduces communication costs. Our implementation and experimental studies revealed that QR-OON outperforms QR-ON by up to 43%, and that QR-ER outperforms QR-ON and QR-OON by up to 10X.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129981812","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}
Splitters are simple objects, implementable with read/write registers, that return directions in {right, down, stop}. Not every process that accesses the object obtains the same direction, and in addition at most one obtains stop. Both in their one-shot and long-lived form, splitters are basic building block of elegant renaming algorithms in shared memory. In a message passing system when less than half of the processes may fail, splitter can be implemented by first simulating shared registers. This is no longer the case if half or more of the processes may fail. We define and implement one-shot and long-lived splitters suited to the majority of failures environment. Our generalized splitters retain most properties of the original splitters, except that they only guarantee that at most ⌊ n/n − f) ⌋ processes return stop, where n is the number of processes and f < n an upper bound on the number of failures. We then adapt Moir and Anderson grid of splitters to solve one-shot and long-lived variant of renaming in which at most ⌊ n/n − f) ⌋ processes may obtain the same name. One of the main challenge consists in composing long-lived generalized splitters.
{"title":"Splitting and Renaming with a Majority of Faulty Processes","authors":"David Bonnin, Corentin Travers","doi":"10.1145/2684464.2684471","DOIUrl":"https://doi.org/10.1145/2684464.2684471","url":null,"abstract":"Splitters are simple objects, implementable with read/write registers, that return directions in {right, down, stop}. Not every process that accesses the object obtains the same direction, and in addition at most one obtains stop. Both in their one-shot and long-lived form, splitters are basic building block of elegant renaming algorithms in shared memory. In a message passing system when less than half of the processes may fail, splitter can be implemented by first simulating shared registers. This is no longer the case if half or more of the processes may fail. We define and implement one-shot and long-lived splitters suited to the majority of failures environment. Our generalized splitters retain most properties of the original splitters, except that they only guarantee that at most ⌊ n/n − f) ⌋ processes return stop, where n is the number of processes and f < n an upper bound on the number of failures. We then adapt Moir and Anderson grid of splitters to solve one-shot and long-lived variant of renaming in which at most ⌊ n/n − f) ⌋ processes may obtain the same name. One of the main challenge consists in composing long-lived generalized splitters.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"22 15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134421642","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}
Poonam Goyal, S. Kumari, Dhruv Kumar, S. Balasubramaniam, Navneet Goyal, Saiyedul Islam, Jagat Sesh Challa
In this paper, we propose an algorithm, DOPTICS, a parallelized version of a popular density based cluster-ordering algorithm OPTICS. Parallelizing OPTICS is challenging because of its strong sequential data access behavior. To achieve high parallelism, a data parallel approach that exploits the underlying indexing structure is proposed. We implement the proposed algorithm for processor nodes in a commodity cluster as well as across cores in a processor. Moreover, the clusters obtained by our algorithm are exactly same as that of classical OPTICS unlike the only existing implementation of the parallel OPTICS. We demonstrate the performance of the proposed algorithm on a commodity cluster which is typically a combination of distributed and shared memory systems. Experimental results on several large real and synthetic data sets with varying dimensions are presented to show speed up and scalability achieved. The speed up obtained is remarkable and is found to scale well with increasing number of processing elements. Performance improvements of the proposed DOPTICS algorithm are due to algorithmic optimizations and parallelization strategy.
{"title":"Parallelizing OPTICS for Commodity Clusters","authors":"Poonam Goyal, S. Kumari, Dhruv Kumar, S. Balasubramaniam, Navneet Goyal, Saiyedul Islam, Jagat Sesh Challa","doi":"10.1145/2684464.2684477","DOIUrl":"https://doi.org/10.1145/2684464.2684477","url":null,"abstract":"In this paper, we propose an algorithm, DOPTICS, a parallelized version of a popular density based cluster-ordering algorithm OPTICS. Parallelizing OPTICS is challenging because of its strong sequential data access behavior. To achieve high parallelism, a data parallel approach that exploits the underlying indexing structure is proposed. We implement the proposed algorithm for processor nodes in a commodity cluster as well as across cores in a processor. Moreover, the clusters obtained by our algorithm are exactly same as that of classical OPTICS unlike the only existing implementation of the parallel OPTICS. We demonstrate the performance of the proposed algorithm on a commodity cluster which is typically a combination of distributed and shared memory systems. Experimental results on several large real and synthetic data sets with varying dimensions are presented to show speed up and scalability achieved. The speed up obtained is remarkable and is found to scale well with increasing number of processing elements. Performance improvements of the proposed DOPTICS algorithm are due to algorithmic optimizations and parallelization strategy.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"211 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123397014","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}
Partial orders are used extensively for modeling and analyzing concurrent computations. In this paper, we define two properties of partially ordered sets: width-extensibility and interleaving-consistency, and show that a partial order can be a valid state based model: (1) of some synchronous concurrent computation iff it is width-extensible, and (2) of some asynchronous concurrent computation iff it is width-extensible and interleaving-consistent. We also show a duality between the event based and state based models of concurrent computations, and give algorithms to convert models between the two domains. When applied to the problem of checkpointing, our theory leads to a better understanding of some existing results and algorithms in the field. It also leads to efficient detection algorithms for predicates whose evaluation requires knowledge of states from all the processes in the system.
{"title":"Necessary and Sufficient Conditions on Partial Orders for Modeling Concurrent Computations","authors":"Himanshu Chauhan, V. Garg","doi":"10.1145/2684464.2684478","DOIUrl":"https://doi.org/10.1145/2684464.2684478","url":null,"abstract":"Partial orders are used extensively for modeling and analyzing concurrent computations. In this paper, we define two properties of partially ordered sets: width-extensibility and interleaving-consistency, and show that a partial order can be a valid state based model: (1) of some synchronous concurrent computation iff it is width-extensible, and (2) of some asynchronous concurrent computation iff it is width-extensible and interleaving-consistent. We also show a duality between the event based and state based models of concurrent computations, and give algorithms to convert models between the two domains. When applied to the problem of checkpointing, our theory leads to a better understanding of some existing results and algorithms in the field. It also leads to efficient detection algorithms for predicates whose evaluation requires knowledge of states from all the processes in the system.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"15 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133842131","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}
We present deterministic distributed algorithms for computing approximate maximum cardinality matchings and approximate maximum weight matchings. Our algorithm for the unweighted case computes a matching whose size is at least (1−ε) times the optimal in Δ O(1/ε) + O(1/ε2) · log* (n) rounds where n is the number of vertices in the graph and Δ is the maximum degree. Our algorithm for the edge-weighted case computes a matching whose weight is at least (1 − ε) times the optimal in log(min{1/ωmin, n/ε})O(1/ε). (Δ O(1/ε) + log*(n)) rounds for edge-weights in [wmin, 1]. The best previous algorithms for both the unweighted case and the weighted case are by Lotker, Patt-Shamir, and Pettie (SPAA 2008). For the unweighted case they give a randomized (1 − ε)-approximation algorithm that runs in O((log(n))ε3) rounds. For the weighted case they give a randomized (1/2 − ε)-approximation algorithm that runs in O(log(ε−1) · log(n)) rounds. Hence, our results improve on the previous ones when the parameters Δ, ε and wmin are constants (where we reduce the number of runs from O(log(n)) to O(log*(n))), and more generally when Δ, 1/ε and 1/wmin are sufficiently slowly increasing functions of n. Moreover, our algorithms are deterministic rather than randomized.
{"title":"Distributed Maximum Matching in Bounded Degree Graphs","authors":"G. Even, Moti Medina, D. Ron","doi":"10.1145/2684464.2684469","DOIUrl":"https://doi.org/10.1145/2684464.2684469","url":null,"abstract":"We present deterministic distributed algorithms for computing approximate maximum cardinality matchings and approximate maximum weight matchings. Our algorithm for the unweighted case computes a matching whose size is at least (1−ε) times the optimal in Δ O(1/ε) + O(1/ε2) · log* (n) rounds where n is the number of vertices in the graph and Δ is the maximum degree. Our algorithm for the edge-weighted case computes a matching whose weight is at least (1 − ε) times the optimal in log(min{1/ωmin, n/ε})O(1/ε). (Δ O(1/ε) + log*(n)) rounds for edge-weights in [wmin, 1]. The best previous algorithms for both the unweighted case and the weighted case are by Lotker, Patt-Shamir, and Pettie (SPAA 2008). For the unweighted case they give a randomized (1 − ε)-approximation algorithm that runs in O((log(n))ε3) rounds. For the weighted case they give a randomized (1/2 − ε)-approximation algorithm that runs in O(log(ε−1) · log(n)) rounds. Hence, our results improve on the previous ones when the parameters Δ, ε and wmin are constants (where we reduce the number of runs from O(log(n)) to O(log*(n))), and more generally when Δ, 1/ε and 1/wmin are sufficiently slowly increasing functions of n. Moreover, our algorithms are deterministic rather than randomized.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122830965","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}
Transactional memory (TM) is a convenient synchronization tool that allows concurrent threads to declare sequences of instructions on shared data as speculative transactions with "all-or-nothing" semantics. It is known that dynamic transactional memory cannot provide wait-free progress ensuring that every transaction commits in a finite number of its own steps. In this paper, we explore the costs of providing wait-freedom to only a subset of transactions. We require that read-only transactions commit in the wait-free manner, while updating transactions are guaranteed to commit only if they run in the absence of concurrency. We show that this kind of partial wait-freedom, combined with attractive requirements like read invisibility or disjoint-access parallelism, incurs considerable complexity costs.
{"title":"On Partial Wait-Freedom in Transactional Memory","authors":"P. Kuznetsov, Srivatsan Ravi","doi":"10.1145/2684464.2684473","DOIUrl":"https://doi.org/10.1145/2684464.2684473","url":null,"abstract":"Transactional memory (TM) is a convenient synchronization tool that allows concurrent threads to declare sequences of instructions on shared data as speculative transactions with \"all-or-nothing\" semantics. It is known that dynamic transactional memory cannot provide wait-free progress ensuring that every transaction commits in a finite number of its own steps. In this paper, we explore the costs of providing wait-freedom to only a subset of transactions. We require that read-only transactions commit in the wait-free manner, while updating transactions are guaranteed to commit only if they run in the absence of concurrency. We show that this kind of partial wait-freedom, combined with attractive requirements like read invisibility or disjoint-access parallelism, incurs considerable complexity costs.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114439039","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}
We consider eager-push epidemic dissemination in a complete graph. Time is divided into synchronous stages. In each stage, a source disseminates ν events. Each event is sent by the source, and forwarded by each node upon its first reception, to f nodes selected uniformly at random, where f is the fanout. We use Game Theory to study the range of f for which equilibria strategies exist, assuming that players are either rational or obedient to the protocol, and that they do not collude. We model interactions as an infinitely repeated game. We devise a monitoring mechanism that extends the repeated game with communication rounds used for exchanging monitoring information, and define strategies for this extended game. We assume the existence of a trusted mediator, that players are computationally bounded such that they cannot break the cryptographic primitives used in our mechanism, and that symmetric ciphering is cheap. Under these assumptions, we show that, if the size of the stream is sufficiently large and players attribute enough value to future utilities, then the defined strategies are Sequential Equilibria of the extended game for any value of f. Moreover, the utility provided to each player is arbitrarily close to that provided in the original game. This shows that we can persuade rational nodes to follow a dissemination protocol that uses any fanout, while arbitrarily minimising the relative overhead of monitoring.
{"title":"On the Range of Equilibria Utilities of a Repeated Epidemic Dissemination Game with a Mediator","authors":"Xavier Vilaça, L. Rodrigues","doi":"10.1145/2684464.2684482","DOIUrl":"https://doi.org/10.1145/2684464.2684482","url":null,"abstract":"We consider eager-push epidemic dissemination in a complete graph. Time is divided into synchronous stages. In each stage, a source disseminates ν events. Each event is sent by the source, and forwarded by each node upon its first reception, to f nodes selected uniformly at random, where f is the fanout. We use Game Theory to study the range of f for which equilibria strategies exist, assuming that players are either rational or obedient to the protocol, and that they do not collude. We model interactions as an infinitely repeated game. We devise a monitoring mechanism that extends the repeated game with communication rounds used for exchanging monitoring information, and define strategies for this extended game. We assume the existence of a trusted mediator, that players are computationally bounded such that they cannot break the cryptographic primitives used in our mechanism, and that symmetric ciphering is cheap. Under these assumptions, we show that, if the size of the stream is sufficiently large and players attribute enough value to future utilities, then the defined strategies are Sequential Equilibria of the extended game for any value of f. Moreover, the utility provided to each player is arbitrarily close to that provided in the original game. This shows that we can persuade rational nodes to follow a dissemination protocol that uses any fanout, while arbitrarily minimising the relative overhead of monitoring.","PeriodicalId":298587,"journal":{"name":"Proceedings of the 16th International Conference on Distributed Computing and Networking","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124496587","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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