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44
Switched PIOA: Parallel Composition via Distributed Scheduling
, 2005
"... This paper presents the framework of switched probabilistic input/output automata (or switched PIOA), augmenting the original PIOA framework with an explicit control exchange mechanism. Using this mechanism, we model a network of processes passing a single token among them, so that the location of t ..."
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Cited by 19 (1 self)
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This paper presents the framework of switched probabilistic input/output automata (or switched PIOA), augmenting the original PIOA framework with an explicit control exchange mechanism. Using this mechanism, we model a network of processes passing a single token among them, so that the location of this token determines which process is scheduled to make the next move. This token structure therefore implements a distributed scheduling scheme: scheduling decisions are always made by the (unique) active component. Distributed scheduling allows us to draw a clear line between local and global nondeterministic choices. We then require that local nondeterministic choices are resolved using strictly local information. This eliminates unrealistic schedules that arise under the more common centralized scheduling scheme. As a result, we are able to prove that our tracestyle semantics is compositional.
On the complexity of asynchronous gossip
 In Proceedings of the 27th ACM Symposium on Principles of Distributed Computing (PODC
"... We study the complexity of gossip in an asynchronous, messagepassing faultprone distributed system. We show that an adaptive adversary can significantly hamper the spreading of a rumor, while an oblivious adversary cannot. The algorithmic techniques proposed in this article can be used for improvi ..."
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Cited by 15 (6 self)
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We study the complexity of gossip in an asynchronous, messagepassing faultprone distributed system. We show that an adaptive adversary can significantly hamper the spreading of a rumor, while an oblivious adversary cannot. The algorithmic techniques proposed in this article can be used for improving the message complexity of distributed algorithms that rely on an alltoall message exchange paradigm and are designed for an asynchronous environment. As an example, we show how to improve the message complexity of asynchronous randomized consensus.
Efficient LowContention Asynchronous Consensus with the ValueOblivious Adversary Scheduler
 DISTRIBUTED COMPUTING
, 2005
"... We consider asynchronous consensus in the shared memory setting. We present the first efficient lowcontention consensus algorithm for the weak adversary scheduler model. The algorithm achieves consensus in O(n log² n) total work and O(log n) (hotspot) contention, both expected and with high probab ..."
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Cited by 12 (1 self)
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We consider asynchronous consensus in the shared memory setting. We present the first efficient lowcontention consensus algorithm for the weak adversary scheduler model. The algorithm achieves consensus in O(n log² n) total work and O(log n) (hotspot) contention, both expected and with high probability. The algorithm assumes the valueoblivious scheduler, which is defined in the paper. Previous efficient consensus algorithms for weak adversaries suffer from &Omega;(n) memory contention.
Lower Bounds for Randomized Consensus under a Weak Adversary
, 2008
"... This paper studies the inherent tradeoff between termination probability and total step complexity of randomized consensus algorithms. It shows that for every integer k, the probability that an fresilient randomized consensus algorithm of n processes does not terminate with agreement within k(n − ..."
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Cited by 12 (0 self)
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This paper studies the inherent tradeoff between termination probability and total step complexity of randomized consensus algorithms. It shows that for every integer k, the probability that an fresilient randomized consensus algorithm of n processes does not terminate with agreement within k(n − f) steps is at least 1 ck, for some constant c. The lower bound holds for asynchronous systems, where processes communicate either by message passing or through shared memory, under a very weak adversary that determines the schedule in advance, without observing the algorithm’s actions. This complements algorithms of Kapron et al. [22], for messagepassing systems, and of Aumann et al. [6, 7], for sharedmemory systems.
Linearizable implementations do not suffice for randomized distributed computation
 In Proceedings of the 43rd annual ACM symposium on Theory of computing, STOC ’11
, 2011
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Randomized waitfree consensus using an atomicity assumption
, 2005
"... Abstract. We present a randomized algorithm for asynchronous waitfree consensus using multiwriter multireader shared registers. This algorithm is based on earlier work by Chor, Israeli and Li (CIL) and is correct under the assumption that processes can perform a random choice and a write operat ..."
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Cited by 10 (0 self)
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Abstract. We present a randomized algorithm for asynchronous waitfree consensus using multiwriter multireader shared registers. This algorithm is based on earlier work by Chor, Israeli and Li (CIL) and is correct under the assumption that processes can perform a random choice and a write operation in one atomic step. The expected total work for our algorithm is shown to be O(N log(logN)), compared with O(N 2) for the CIL algorithm, and O(N logN) for the best known weak adversary algorithm. We also model check instances of our algorithm using the probabilistic model checking tool PRISM.
Coalescing random walks and voting on graphs
 In Proceedings of the 31st ACM symposium on Principles of distributed computing (PODC
, 2012
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Distributed agreement with optimal communication complexity
 In Proceedings of the 21st ACMSIAM Symposium on Discrete Algorithms (SODA
, 2010
"... We consider the problem of faulttolerant agreement in a crashprone synchronous system. We present a new randomized consensus algorithm that achieves optimal communication efficiency, using only O(n) bits of communication, and terminates in (almost optimal) time O(log n), with high probability. The ..."
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Cited by 8 (3 self)
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We consider the problem of faulttolerant agreement in a crashprone synchronous system. We present a new randomized consensus algorithm that achieves optimal communication efficiency, using only O(n) bits of communication, and terminates in (almost optimal) time O(log n), with high probability. The same protocol, with minor modifications, can also be used in partially synchronous networks, guaranteeing correct behavior even in asynchronous executions, while maintaining efficient performance in synchronous executions. Finally, the same techniques also yield a randomized, faulttolerant gossip protocol that terminates in O(log ∗ n) rounds using O(n) messages (with bit complexity that depends on the data being gossiped). 1
Randomized mutual exclusion with sublogarithmic RMRcomplexity
, 2011
"... Mutual exclusion is a fundamental distributed coordination problem. Sharedmemory mutual exclusion research focuses on localspin algorithms and uses the remote memory references (RMRs) metric. Attiya, Hendler, and Woelfel (40th STOC, 2008) established an �(log N) lower bound on the number of RMRs ..."
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Cited by 8 (3 self)
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Mutual exclusion is a fundamental distributed coordination problem. Sharedmemory mutual exclusion research focuses on localspin algorithms and uses the remote memory references (RMRs) metric. Attiya, Hendler, and Woelfel (40th STOC, 2008) established an �(log N) lower bound on the number of RMRs incurred by processes as they enter and exit the critical section, where N is the number of processes in the system. This matches the upper bound of Yang and Anderson (Distrib. Comput. 9(1):51–60, 1995). The upper and lower bounds apply for algorithms that only use read and write operations. The lower bound of Attiya et al., however, only holds for deterministic algorithms. The question of whether randomized mutual exclusion algorithms, using reads and writes only, can achieve sublogarithmic expected RMR complexity remained open. We answer this question in the affirmative by presenting starvationfree randomized mutual exclusion algorithms for the cache coherent (CC) and the distributed shared memory (DSM) model that have sublogarithmic expected RMR complexity against the strong adversary. More specifically, each process incurs an expected number of O(log N / log log N) RMRs per passage through the entry and exit sections, while in the worst case the number of RMRs is O(log N). P. Woelfel was supported by NSERC.