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On Evolution, Search, Optimization, Genetic Algorithms and Martial Arts  Towards Memetic Algorithms
, 1989
"... Short abstract, isn't it? P.A.C.S. numbers 05.20, 02.50, 87.10 1 Introduction Large Numbers "...the optimal tour displayed (see Figure 6) is the possible unique tour having one arc fixed from among 10 655 tours that are possible among 318 points and have one arc fixed. Assuming that one could ..."
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Cited by 187 (10 self)
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Short abstract, isn't it? P.A.C.S. numbers 05.20, 02.50, 87.10 1 Introduction Large Numbers "...the optimal tour displayed (see Figure 6) is the possible unique tour having one arc fixed from among 10 655 tours that are possible among 318 points and have one arc fixed. Assuming that one could possibly enumerate 10 9 tours per second on a computer it would thus take roughly 10 639 years of computing to establish the optimality of this tour by exhaustive enumeration." This quote shows the real difficulty of a combinatorial optimization problem. The huge number of configurations is the primary difficulty when dealing with one of these problems. The quote belongs to M.W Padberg and M. Grotschel, Chap. 9., "Polyhedral computations", from the book The Traveling Salesman Problem: A Guided tour of Combinatorial Optimization [124]. It is interesting to compare the number of configurations of realworld problems in combinatorial optimization with those large numbers arising in Cosmol...
Metasystems: an approach combining parallel processing and heterogeneous distributed computing systems
 J. PARALLEL & DISTRIBUTED COMPUT
"... A metasystem is a single computing resource composed of a heterogeneous group of autonomous computers linked together by a network. The interconnection network needed to construct large metasystems will soon be in place. To fully exploit these new systems, software that is easy to use, supports larg ..."
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Cited by 64 (16 self)
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A metasystem is a single computing resource composed of a heterogeneous group of autonomous computers linked together by a network. The interconnection network needed to construct large metasystems will soon be in place. To fully exploit these new systems, software that is easy to use, supports large degrees of parallelism, and hides the complexity of the underlying physical architecture must be developed. In this paper we describe our metasystem vision, our approach to constructing a metasystem testbed, and early experimental results. Our approach combines features from earlier work on both parallel processing systems and heterogeneous distributed computing systems. Using the testbed we have found that data coercion costs are not a serious obstacle to high performance, but that load imbalance induced by differing processor capabilities can limit performance. We then present a mechanism to overcome load imbalance that utilizes userprovided callbacks.
TPVM: Distributed Concurrent Computing with Lightweight Processes
, 1995
"... The TPVM (Threadsoriented PVM) system is an experimental auxiliary subsystem for the PVM distributed system, which supports the use of lightweight processes or "threads" as the basic unit of parallelism and scheduling. TPVM provides a library interface which presents both a traditional, task bas ..."
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Cited by 38 (3 self)
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The TPVM (Threadsoriented PVM) system is an experimental auxiliary subsystem for the PVM distributed system, which supports the use of lightweight processes or "threads" as the basic unit of parallelism and scheduling. TPVM provides a library interface which presents both a traditional, task based, explicit message passing model, as well as a datadriven scheduling model that enables straightforward specification of computation based on data dependencies.
The Mentat Computation Model  DataDriven Support for Dynamic ObjectOriented Parallel Processing
, 1993
"... Mentat is an objectoriented parallel processing system developed at the University of Virginia which has been ported to a variety of MIMD architectures. The computation model employed by Mentat is macro dataflow (MDF), a medium grain, scalable, datadriven computation model that supports both high ..."
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Cited by 23 (5 self)
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Mentat is an objectoriented parallel processing system developed at the University of Virginia which has been ported to a variety of MIMD architectures. The computation model employed by Mentat is macro dataflow (MDF), a medium grain, scalable, datadriven computation model that supports both high degrees of parallelism and the objectoriented paradigm. A key aspect of the model is that it can be efficiently implemented. Inspired by dataflow, MDF retains the graphbased, datadriven, selfsynchronizing aspects of dataflow. MDF address the shortcomings that dataflow exhibits when applied to distributed memory MIMD architectures by extending dataflow in three ways: (1) it is medium grain  actors are of sufficient computational complexity to amortize overhead costs, (2) program graphs are dynamically constructed at runtime  this permits dynamic function binding as required by the objectoriented paradigm and increases the average computation granularity, and (3) actors may maintai...
Scheduling Parallel Computations in a Heterogeneous Environment
, 1995
"... A metasystem is a shared ensemble of workstations, vector, and parallel machines ..."
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Cited by 14 (6 self)
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A metasystem is a shared ensemble of workstations, vector, and parallel machines
Parallelization of NonSimultaneous Iterative Methods for Systems of Linear Equations
, 1994
"... . This paper proposes a general execution scheme for parallelizing a class of iterative algorithms characterized by strong data dependencies between iterations. This class includes nonsimultaneous iterative methods for solving systems of linear equations, such as GaussSeidel and SOR, and long ..."
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Cited by 11 (1 self)
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. This paper proposes a general execution scheme for parallelizing a class of iterative algorithms characterized by strong data dependencies between iterations. This class includes nonsimultaneous iterative methods for solving systems of linear equations, such as GaussSeidel and SOR, and longrange methods. The paper presents a set of code transformations that make it possible to derive the parallel form of the algorithm starting from sequential code. The performance of the proposed execution scheme are then analyzed with respect to an abstract model of the underlying parallel machine. 1 Introduction Considerable research activity has been devoted in recent years to the programming of parallel computers. In this respect, special attention has been paid to computational science, which currently represents the main field where parallel computers can be successfully employed [1, 5, 6]. Parallelization techniques concentrate on data parallelism, a characteristic of most computa...
Blending Heuristics with a PopulationBased Approach: A "Memetic" Algorithm for the Traveling Salesman Problem
 REPORT 9212, UNIVERSIDAD NACIONAL DE LA PLATA, C.C. 75, 1900 LA PLATA
, 1994
"... Very recently many researchers, with backgrounds in parallel computing, started to develop hybrids of traditional genetic algorithms. The main departure from standard genetic algorithms is that these new methods incorporate specific heuristics for the problem at hand (drawing on a tradition which ha ..."
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Cited by 10 (4 self)
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Very recently many researchers, with backgrounds in parallel computing, started to develop hybrids of traditional genetic algorithms. The main departure from standard genetic algorithms is that these new methods incorporate specific heuristics for the problem at hand (drawing on a tradition which has roots outside the genetic framework) and which we apply within a stochastic game that exerts a selective pressure. The heuristics are used for periods of individual optimization, that is when agents do not interact. New computational results for the Traveling Salesman Problem will be presented in this paper. The approach is prepared to include Tabu Search techniques, introducing a new crossover operator (which is called Random Respectful Corner Recombination) and a special pair of a topology and set of rules for the interaction between agents. The approach has a natural parallelism and a feature called superlinear speedup will also be discussed.
A CompetitiveCooperative Approach to Complex Combinatorial Search
, 1991
"... Combinatorial optimization problems confront us with the problem of searching in a huge configuration space. Associated with each of these configurations is the value of a utility function and the optimization task generally consists of finding the configuration which has either the lowest or the hi ..."
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Cited by 8 (4 self)
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Combinatorial optimization problems confront us with the problem of searching in a huge configuration space. Associated with each of these configurations is the value of a utility function and the optimization task generally consists of finding the configuration which has either the lowest or the highest cost of all. Among the most difficult of these problems are those which belong to the NPcomplete class for which, it is conjectured, there does not exist a polynomialtime algorithm that can give optimal solutions. We have designed a CompetitiveCooperative Search to deal with these problems. A number of distinguishable individuals, arranged in a certain topology, compete and cooperate with the other individuals during the search. The method uses techniques from Simulated Annealing and Genetic Algorithms and is inspired by analogies with evolving systems, both social and biological. Its performance is being tested on large Traveling Salesman Problem instances, like the LinKernighan 3...
Hierarchical TreeStructures as Adaptive Meshes
, 1993
"... 1 Introduction Two basic types of simulations exist for modeling systems of many particles: gridbased (point particles indirectly interacting with one another through the potential calculated from equivalent particle densities on a mesh) and particlebased (point particles directly interacting wit ..."
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Cited by 7 (2 self)
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1 Introduction Two basic types of simulations exist for modeling systems of many particles: gridbased (point particles indirectly interacting with one another through the potential calculated from equivalent particle densities on a mesh) and particlebased (point particles directly interacting with a one another through potentials at their positions calculated from the other particles in the system). Gridbased solvers traditionally model continuum problems, such as fluid and gas systems, and mixed particlecontinuum systems. Particlebased solvers find more use modeling discrete systems such as stars within galaxies or other rarefied gases. Many different physical systems, including electromagnetic interactions, gravitational interactions, and fluid vortex interactions, all are governed by Poisson's Equation: r 2 OE = \Gamma4ßGae; (1) for the gravitational case. To evolve N particles in time, the exact solution to the problem requires calculating the force contribution to each pa...
Prototyping Nbody Simulation in Proteus
, 1992
"... This paper explores the use of Proteus, an architectureindependent language suitable for prototyping parallel and distributed programs. Proteus is a highlevel imperative notation based on sets and sequences with a single construct for the parallel composition of processes communicating through sha ..."
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Cited by 6 (3 self)
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This paper explores the use of Proteus, an architectureindependent language suitable for prototyping parallel and distributed programs. Proteus is a highlevel imperative notation based on sets and sequences with a single construct for the parallel composition of processes communicating through shared memory. Several different parallel algorithms for Nbody simulation are presented in Proteus, illustrating how Proteus provides a common foundation for expressing the various parallel programming models. This common foundation allows prototype parallel programs to be tested and evolved without the use of machinespecific languages. To transform prototypes to implementations on specific architectures, program refinement techniques are utilized. Refinement strategies are illustrated that target broadspectrum parallel intermediate languages, and their viability is demonstrated by refining an Nbody algorithm to dataparallel CVL code.