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CONTENTION RESOLUTION IN HASHING BASED SHARED MEMORY SIMULATIONS
, 2000
"... In this paper we study the problem of simulating shared memory on the distributed memory machine (DMM). Our approach uses multiple copies of shared memory cells, distributed among the memory modules of the DMM via universal hashing. The main aim is to design strategies that resolve contention at th ..."
Abstract

Cited by 11 (3 self)
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In this paper we study the problem of simulating shared memory on the distributed memory machine (DMM). Our approach uses multiple copies of shared memory cells, distributed among the memory modules of the DMM via universal hashing. The main aim is to design strategies that resolve contention at the memory modules. Extending results and methods from random graphs and very fast randomized algorithms, we present new simulation techniques that enable us to improve the previously best results exponentially. In particular, we show that an nprocessor CRCW PRAM can be simulated by an nprocessor DMM with delay O(log log log n log ∗ n), with high probability. Next we describe a general technique that can be used to turn these simulations into timeprocessor optimal ones, in the case of EREW PRAMs to be simulated. We obtain a timeprocessor optimal simulation of an (n log log log n log ∗ n)processor EREW PRAM on an nprocessor DMM with delay O(log log log n log ∗ n), with high probability. When an (n log log log n log ∗ n)processor CRCW PRAM is simulated, the delay is only by a log ∗ n factor larger. We further demonstrate that the simulations presented can not be significantly improved using our techniques. We show an Ω(log log log n / log log log log n) lower bound on the expected delay for a class of PRAM simulations, called topological simulations, that covers all previously known simulations as well as the simulations presented in the paper.
Parallel AlternatingDirection Access Machine
, 1996
"... . This paper presents a theoretical study of a model of parallel computations called Parallel AlternatingDirection Access Machine (padam). padam is an abstraction of the multiprocessor computers adena /adenart and a prototype architecture usc/omp. The main feature of padam is the organization of a ..."
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Cited by 7 (3 self)
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. This paper presents a theoretical study of a model of parallel computations called Parallel AlternatingDirection Access Machine (padam). padam is an abstraction of the multiprocessor computers adena /adenart and a prototype architecture usc/omp. The main feature of padam is the organization of access to the global memory: (1) the memory modules are arranged as a 2dimensional array, (2) each processor is assigned to a row and a column, (3) the processors switch synchronously between row and column access modes, and can access any of the assigned modules in each mode without conflicts. Since the padam processors have such a restricted access to the partially shared memory, developing tools to enhance flexibility of access to the memory is important. The paper concentrates on these issues. 1 Introduction An important goal in the study of parallel computation is to develop models which are close to real machines but abstract from technical details and provide a vehicle to design and ...
Decremental Biconnectivity on Planar Graphs
"... : In this paper we present a (randomized) algorithm for maintaining the biconnected components of a dynamic planar graph of n vertices under deletions of edges. The biconnected components can be maintained under any sequence of edge deletions in a total of O(n log n) time, with high probability. Thi ..."
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Cited by 2 (0 self)
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: In this paper we present a (randomized) algorithm for maintaining the biconnected components of a dynamic planar graph of n vertices under deletions of edges. The biconnected components can be maintained under any sequence of edge deletions in a total of O(n log n) time, with high probability. This gives O(logn) amortized time per edge deletion, which improves previous (deterministic) results from [6] due to Giammarresi and Italiano, where O(n log 2 n) amortized time is needed. Our work describes a simplification of the data structures from [6] and uses dynamic perfect hashing to reduce the running time. As in [6], we only need O(n) space. Finally we describe some simply additional operations on the decremental data structure. By aid of them this the data structure is applicable for finding efficiently a \Deltaspanning tree in a biconnected planar graph with a maximum degree 2\Delta \Gamma 2 do to Czumaj and Strothmann [2]. Key Words: dynamic algorithms, graph algorithms, graph c...
A reliable randomized algorithm for the . . .
, 1997
"... The following two computational problems are studied: Duplicate grouping: Assume that n items are given, each of which is labeled by an integer key from the set 0,..., U � 1 4. Store the items in an array of size n such that items with the same key occupy a contiguous segment of the array. Closest p ..."
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The following two computational problems are studied: Duplicate grouping: Assume that n items are given, each of which is labeled by an integer key from the set 0,..., U � 1 4. Store the items in an array of size n such that items with the same key occupy a contiguous segment of the array. Closest pair: Assume that a multiset of n points in the ddimensional Euclidean space is given, where d � 1 is a fixed integer. Each point is represented as a dtuple of integers in the range 0,..., U � 14 Ž or of arbitrary real numbers.. Find a closest pair, i.e., a pair of points whose distance is minimal over all such pairs.