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A Decomposition of MultiDimensional Point Sets with Applications to kNearestNeighbors and nBody Potential Fields
 J. ACM
, 1992
"... We define the notion of a wellseparated pair decomposition of points in ddimensional space. We then develop efficient sequential and parallel algorithms for computing such a decomposition. We apply the resulting decomposition to the efficient computation of knearest neighbors and nbody potential ..."
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Cited by 242 (4 self)
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We define the notion of a wellseparated pair decomposition of points in ddimensional space. We then develop efficient sequential and parallel algorithms for computing such a decomposition. We apply the resulting decomposition to the efficient computation of knearest neighbors and nbody potential fields.
Social Potential Fields: A Distributed Behavioral Control for Autonomous Robots
, 1999
"... A Very Large Scale Robotic (VLSR) system may consist of from hundreds to perhaps tens of thousands or more autonomous robots. The costs of robots are going down, and the robots are getting more compact, more capable, and more flexible. Hence, in the near future, we expect to see many industrial and ..."
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Cited by 122 (1 self)
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A Very Large Scale Robotic (VLSR) system may consist of from hundreds to perhaps tens of thousands or more autonomous robots. The costs of robots are going down, and the robots are getting more compact, more capable, and more flexible. Hence, in the near future, we expect to see many industrial and military applications of VLSR systems in tasks such as assembling, transporting, hazardous inspection, patrolling, guarding and attacking. In this paper, we propose a new approach for distributed autonomous control of VLSR systems. We define simple artificial force laws between pairs of robots or robot groups. The force laws are inversepower force laws, incorporating both attraction and repulsion. The force laws can be distinct and to some degree they reflect the 'social relations' among robots. Therefore we call our method social potential fields. An individual robot's motion is controlled by the resultant artificial force imposed by other robots and other components of the system. The approach is distributed in that the force calculations and motion control can be done in an asynchronous and distributed manner. We also extend the social potential fields model to use spring laws as force laws. This paper presents the first and a preliminary study on applying potential fields to distributed autonomous multirobot control. We describe the generic framework of our social potential fields method. We show with computer simulations that the method can yield interesting and useful behaviors among robots, and we give examples of possible industrial and military applications. We also identify theoretical problems for future studies. 1999 Published by Elsevier Science B.V. All rights reserved.
Load Balancing and Data Locality in the Parallelization of the Fast Multipole Algorithm
, 1996
"... Scientific problems are often irregular, large and computationally intensive. Efficient parallel implementations of algorithms that are employed in finding solutions to these problems play an important role in the development of science. This thesis studies the parallelization of a certain class of ..."
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Cited by 13 (9 self)
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Scientific problems are often irregular, large and computationally intensive. Efficient parallel implementations of algorithms that are employed in finding solutions to these problems play an important role in the development of science. This thesis studies the parallelization of a certain class of irregular scientific problems, the Nbody problem, using a classical hierarchical algorithm: the Fast Multipole Algorithm (FMA). Hierarchical Nbody algorithms in general, and the FMA in particular, are amenable to parallel execution. However, performance gains are difficult to obtain, due to load imbalances that are primarily caused by the irregular distribution of bodies and of computation domains. Understanding application characteristics is essential for obtaining high performance implementations on parallel machines. After surveying the available parallelism in the FMA, we address the problem of exploiting this parallelism with partitioning and scheduling techniques that optimally map i...
A DataParallel Implementation of the Adaptive Fast Multipole Algorithm
, 1993
"... Given an ensemble of n bodies in space whose interaction is governed by a potential function, the Nbody problem is to calculate the force on each body in the ensemble that results from its interaction with all other bodies. An efficient algorithm for this problem is critical in the simulation of mo ..."
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Cited by 11 (1 self)
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Given an ensemble of n bodies in space whose interaction is governed by a potential function, the Nbody problem is to calculate the force on each body in the ensemble that results from its interaction with all other bodies. An efficient algorithm for this problem is critical in the simulation of molecular dynamics, turbulent fluid flow, intergalactic matter and other problems. The fast multipole algorithm (FMA) developed by Greengard approximates the solution with bounded error in time O(n ). For nonuniform distributions of bodies, an adaptive variation of the algorithm is required to maintain this time complexity. The parallel execution of the FMA poses complex implementation issues in the decomposition of the problem over processors to reduce communication. As a result the 3D Adaptive FMA has, to our knowledge, never been implemented on a scalable parallel computer. This paper describes several variations on the parallel adaptive 3D FMA algorithm that are expressed using the datapa...
The Parallel Implementation of Nbody Algorithms
, 1994
"... This dissertation studies issues critical to efficient Nbody simulations on parallel computers. The Nbody problem poses several challenges for distributedmemory implementation: adaptive distributed data structures, irregular data access patterns, and irregular and adaptive communication patterns. ..."
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Cited by 11 (1 self)
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This dissertation studies issues critical to efficient Nbody simulations on parallel computers. The Nbody problem poses several challenges for distributedmemory implementation: adaptive distributed data structures, irregular data access patterns, and irregular and adaptive communication patterns. We introduce new techniques to maintain dynamic irregular data structures, to vectorize irregular computational structures, and for efficient communication. We report results from experiments on the Connection Machine CM5. The results demonstrate the performance advantages of design simplicity; the code provides generality of use on various messagepassing architectures. Our methods have been used as the basis of a C++ library that provides abstractions for tree computations to ease the development of different Nbody codes. This dissertation also presents the atomic message model to capture the important factors of efficient communication in messagepassing systems. The atomic model was m...
Large Scale Simulations of Complex Systems Part I: Conceptual Framework
, 1997
"... In this working document, we report on a new approach to high performance simulation. The main inspiration to this approach is the concept of complex systems: disparate elements with well defined interactions rules and non nonlinear emergent macroscopic behavior. We provide arguments and mechanisms ..."
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In this working document, we report on a new approach to high performance simulation. The main inspiration to this approach is the concept of complex systems: disparate elements with well defined interactions rules and non nonlinear emergent macroscopic behavior. We provide arguments and mechanisms to abstract temporal and spatial locality from the application and to incorporate this locality into the complete design cycle of modeling and simulation on parallel architectures. Although the main application area discussed here is physics, the presented Virtual Particle (VIP) paradigm in the context of Dynamic Complex Systems (DCS), is applicable to other areas of compute intensive applications. Part I deals with the concepts behind the VIP and DCS models. A formal approach to the mapping of application taskgraphs to machine taskgraphs is presented. The major part of section 3 has recently (July 1997) been accepted for publication in Complexity. In Part II we will elaborate on the execution behavior of
THE WAY THE BALL BOUNCES
"... The billiard ball rolls smartly along the baize, aimed for another ball at the far end of the table. The player watching its trajectory anticipates the solid tlock! of contact, to be followed by the familiar textbook demonstration of the conservation of energy and momentum. But something has gone aw ..."
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The billiard ball rolls smartly along the baize, aimed for another ball at the far end of the table. The player watching its trajectory anticipates the solid tlock! of contact, to be followed by the familiar textbook demonstration of the conservation of energy and momentum. But something has gone awry on this billiards table. The moving ball passes right through the stationary one, without altering its own motion or disturbing the repose of its target. And then the rolling ball glides wraithlike through the rail at the edge of the table and continues imperturbably sailing across the room, with no inclination to fall to the floor. What’s going on here? It’s not quantum tunneling;