Sergio Rajsbaum

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The Distributed Computing Column covers the theory of systems that are composed of a number of interacting computing elements. These include problems of communication and networking, databases, distributed shared memory, multiprocessor architectures, operating systems, verification, Internet, and the Web. This issue consists of: • “Travelling through(More)
We present a shared memory algorithm that allows a set of f+1 processes to wait-free “simulate” a larger system of n processes, that may also exhibit up to f stopping failures. Applying this simulation algorithm to the k-set-agreement problem enables conversion of an arbitrary k-fault-tolerant{\it n}-process solution for the k-set-agreement problem into a(More)
This paper introduces and explores a new <italic>condition based</italic> approach to solve the consensus problem in asynchronous systems. The approach consists of identifying sets of input vectors, called <italic>conditions</italic>, for which it is possible to design a protocol solving consensus despite the occurrence of up to <italic>f</italic> process(More)
The problem of achieving optimal clock synchronization in a communication network with arbitrary topology and perfect clocks (that do not drift) is studied. Clock synchronization algorithms are presented for a large family of delay assumptions. Our algorithms are modular and consist of three major components. The first component holds for any type of delay(More)
This paper introduces a simple notion of layering as a tool for analyzing well-behaved runs of a given model of distributed computation. Using layering, a model-independent analysis of the consensus problem is performed and then applied to proving lower bounds and impossibility results for consensus in a number of familiar and less familiar models. The(More)
Topological methods have yielded a variety of lower bounds and impossibility results for distributed computing. In this paper, we introduce a new tool for proving impossibility results, based on a core theorem of algebraic topology, the acyclic carrier theorem, which uniies, generalizes, and extends earlier results.
We take a signi cant step toward unifying the synchronous semi synchronous and asynchronous message passing models of distributed computation The key idea is the concept of a pseudosphere a new combinatorial structure in which each process from a set of processes is independently assigned a value from a set of values Pseudospheres have a number of nice(More)