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405
A Heuristic Method for the Set Covering Problem
 OPERATIONS RESEARCH
, 1995
"... We present a Lagrangianbased heuristic for the wellknown Set Covering Problem (SCP). The algorithm was initially designed for solving very large scale SCP instances, involving up to 5,000 rows and 1,000,000 columns, arising from crew scheduling in the Italian Railway Company, Ferrovie dello St ..."
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Cited by 91 (13 self)
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We present a Lagrangianbased heuristic for the wellknown Set Covering Problem (SCP). The algorithm was initially designed for solving very large scale SCP instances, involving up to 5,000 rows and 1,000,000 columns, arising from crew scheduling in the Italian Railway Company, Ferrovie dello Stato SpA. In 1994 Ferrovie dello Stato SpA, jointly with the Italian Operational Research Society, organized a competition, called FASTER, intended to promote the development of algorithms capable of producing good solutions for these instances, since the classical approaches meet with considerable difficulties in tackling them. The main characteristics of the algorithm we propose are (1) a dynamic pricing scheme for the variables, akin to that used for solving largescale LP's, to be coupled with subgradient optimization and greedy algorithms, and (2) the systematic use of column fixing to obtain improved solutions. Moreover, we propose a number of improvements on the standard way o...
Algorithms for the Set Covering Problem
 Annals of Operations Research
, 1998
"... The Set Covering Problem (SCP) is a main model for several important applications, including crew scheduling in railway and masstransit companies. ..."
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Cited by 90 (4 self)
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The Set Covering Problem (SCP) is a main model for several important applications, including crew scheduling in railway and masstransit companies.
Starfire: Extending the SMP Envelope
 IEEE Micro
, 1998
"... This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Sun Microsystem's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for a ..."
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Cited by 81 (0 self)
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This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Sun Microsystem's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by sending a blank email message to info.pub.permission@ieee.org. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.
Benchmarking Java against C and Fortran for Scientific Applications
 In Proceedings of ACM Java Grande/ISCOPE Conference
, 2001
"... Increasing interest is being shown in the use of Java for scienti c applications. The Java Grande benchmark suite [4] was designed with such applications primarily in mind. The perceived lack of performance of Java still deters many potential users, despite recent advances in justintime (JIT) and ..."
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Cited by 73 (2 self)
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Increasing interest is being shown in the use of Java for scienti c applications. The Java Grande benchmark suite [4] was designed with such applications primarily in mind. The perceived lack of performance of Java still deters many potential users, despite recent advances in justintime (JIT) and adaptive compilers. There are however few benchmark results available comparing Java to more traditional languages such as C and Fortran. To address this issue, a subset of the Java Grande Benchmarks have been rewritten in C and Fortran allowing direct performance comparisons between the three languages. The performance of a range of Java execution environments, C and Fortran compilers have been tested across a number of platforms using the suite. These demonstrate that on some platforms (notably Intel Pentium) the performance gap is now quite small. Keywords Java, C, Fortran, performance, benchmarking, scientic applications
The TorusWrap Mapping For Dense Matrix Calculations On Massively Parallel Computers
 SIAM J. SCI. STAT. COMPUT
, 1994
"... Dense linear systems of equations are quite common in science and engineering, arising in boundary element methods, least squares problems and other settings. Massively parallel computers will be necessary to solve the large systems required by scientists and engineers, and scalable parallel algori ..."
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Cited by 71 (5 self)
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Dense linear systems of equations are quite common in science and engineering, arising in boundary element methods, least squares problems and other settings. Massively parallel computers will be necessary to solve the large systems required by scientists and engineers, and scalable parallel algorithms for the linear algebra applications must be devised for these machines. A critical step in these algorithms is the mapping of matrix elements to processors. In this paper, we study the use of the toruswrap mapping in general dense matrix algorithms, from both theoretical and practical viewpoints. We prove that, under reasonable assumptions, this assignment scheme leads to dense matrix algorithms that achieve (to within a constant factor) the lower bound on interprocessor communication. We also show that the toruswrap mapping allows algorithms to exhibit less idle time, better load balancing and less memory overhead than the more common row and column mappings. Finally, we discuss ...
Supercomputer Performance Evaluation and the Perfect Benchmarks
 In Proceedings of the 1990 ACM International Conference on Supercomputing
, 1990
"... In the past three years, the Perfect Benchmark TM Suite has evolved from a supercomputer performance evaluation plan, presented by Kuck and Sameh at the 1987 International Conference on Supercomputing, to a vigorous international activity. This paper surveys the current state of supercomputer perf ..."
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Cited by 68 (0 self)
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In the past three years, the Perfect Benchmark TM Suite has evolved from a supercomputer performance evaluation plan, presented by Kuck and Sameh at the 1987 International Conference on Supercomputing, to a vigorous international activity. This paper surveys the current state of supercomputer performance evaluation with particular focus on the methodology adopted by the Perfect effort. While there has been considerable success in achieving the goals of the plan, some issues remain unresolved, and new questions have surfaced. 1 Introduction During the four decades since the invention of the transistor, performance increases in computers have been attributable, in large part, to increases in hardware speed, averaging an order of magnitude every seven years. In recent years, the progress of hardware technology has begun to slow as certain fundamental limits (ie. the speed of light and the width of the atom) have been approached. In an effort to sustain increases in the peak speed of ne...
Some tests of generalized bisection
 ACM Trans. Math. Software
, 1987
"... This paper addresses the task of reliably finding approximations to all solutions to a system of nonlinear equations within a region defined by bounds on each of the individual coordinates. Various forms of generalized bisection were proposed some time ago for this task. This paper systematically co ..."
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Cited by 59 (5 self)
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This paper addresses the task of reliably finding approximations to all solutions to a system of nonlinear equations within a region defined by bounds on each of the individual coordinates. Various forms of generalized bisection were proposed some time ago for this task. This paper systematically compares such generalized bisection algorithms to themselves, to continuation methods, and to hybrid steepest descent/quasiNewton methods. A specific algorithm containing novel “expansion ” and “exclusion ” steps is fully described, and the effectiveness of these steps is evaluated. A test problem consisting of a small, highdegree polynomial system that is appropriate for generalized bisection, but very difticult for continuation methods, is presented. This problem forms part of a set of 17 test problems from published literature on the methods being compared; this test set is fully described here.
OutofOrder Vector Architectures
, 1997
"... Register renaming and outoforder instruction issue are now commonly used in superscalar processors. These techniques can also be used to significant advantage in vector processors, as this paper shows. Performance is improved and available memory bandwidth is used more effectively. Using a trace d ..."
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Cited by 57 (21 self)
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Register renaming and outoforder instruction issue are now commonly used in superscalar processors. These techniques can also be used to significant advantage in vector processors, as this paper shows. Performance is improved and available memory bandwidth is used more effectively. Using a trace driven simulation we compare a conventional vector implementation, based on the Convex C3400, with an outoforder, register renaming, vector implementation. When the number of physical registers is above 12, outoforder execution coupled with register renaming provides a speedup of 1.241.72 for realistic memory latencies. Outoforder techniques also tolerate main memory latencies of 100 cycles with a performance degradation less than 6%. The mechanisms used for register renaming and outoforder issue can be used to support precise interrupts  generally a difficult problem in vector machines. When precise interrupts are implemented, there is typically less than a 10% degradation in performance. A new technique based on register renaming is targeted at dynamically eliminating spill code; this technique is shown to provide an extra speedup ranging between 1.10 and 1.20 while reducing total memory traffic by an average of 1520%.
Job Shop Scheduling by Local Search
 INFORMS JOURNAL ON COMPUTING
, 1994
"... We survey solution methods for the job shop scheduling problem with an emphasis on local search. Both deterministic and randomized local search methods as well as the proposed neighborhoods are discussed. We compare the computational performance of the various methods in terms of their effectiveness ..."
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Cited by 56 (0 self)
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We survey solution methods for the job shop scheduling problem with an emphasis on local search. Both deterministic and randomized local search methods as well as the proposed neighborhoods are discussed. We compare the computational performance of the various methods in terms of their effectiveness and efficiency on a standard set of problem instances.
Parallel Integer Relation Detection: Techniques and Applications
 Mathematics of Computation
, 2000
"... Let {x1,x2, ···,xn} be a vector of real numbers. An integer relation algorithm is a computational scheme to find the n integers ak, if they exist, such that a1x1 +a2x2 +···+ anxn = 0. In the past few years, integer relation algorithms have been utilized to discover new results in mathematics and phy ..."
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Cited by 55 (35 self)
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Let {x1,x2, ···,xn} be a vector of real numbers. An integer relation algorithm is a computational scheme to find the n integers ak, if they exist, such that a1x1 +a2x2 +···+ anxn = 0. In the past few years, integer relation algorithms have been utilized to discover new results in mathematics and physics. Existing programs for this purpose require very large amounts of computer time, due in part to the requirement for multiprecision arithmetic, yet are poorly suited for parallel processing. This paper presents a new integer relation algorithm designed for parallel computer systems, but as a bonus it also gives superior results on single processor systems. Singleand multilevel implementations of this algorithm are described, together with performance results on a parallel computer system. Several applications of these programs are discussed, including some new results in mathematical number theory, quantum field theory and chaos theory.