46294089
1992 Gordon Bell Prize Winners
62731399
NAS parallel benchmark results
The NAS (Numerical Aerodynamic Simulation) parallel benchmarks have been developed at NASA Ames Research Center to study the performance of parallel supercomputer. The eight benchmark problems are specified in a 'pencil and paper' fashion. The performance results of various systems using the NAS parallel benchmarks are presented. These results represent the best results that have been reported to the authors for the specific systems listed. They represent implementation efforts performed by personnel in both the NAS Applied Research Branch of NASA Ames Research Center and in other organizations.<<ETX>>
9150119
Thick-Restart Lanczos Method for Symmetric Eigenvalue Problems
This paper describes a restarted Lanczos algorithm that particularly suitable for implementation on distributed machines. The only communication operation is requires outside of the matrix-vector multiplication is a global sum. For most large eigenvalue problems, the global sum operation takes a small fraction of the total execution time. The majority of the computer is spent in the matrix-vector multiplication. Efficient parallel matrix-vector multiplication routines can be found in many parallel sparse matrix packages such as AZTEC [9], BLOCK-SOLVE [10], PETSc [3], P_SPARSLIB. For this reason, our main emphasis in this paper is to demonstrate the correctness and the effectiveness of the new algorithm.
38908855
Large-Scale SVD and Subspace-Based Methods for Information Retrieval
A theoretical foundation for latent semantic indexing (LSI) is proposed by adapting a model first used in array signal processing to the context of information retrieval using the concept of subspaces. It is shown that this subspace-based model coupled with minimal description length (MDL) principle leads to a statistical test to determine the dimensions of the latent-concept subspaces in LSI. The effect of weighting on the choice of the optimal dimensions of latent-concept subspaces is illustrated. It is also shown that the model imposes a so-called low-rank-plus-shift structure that is approximately satisfied by the cross-product of the term-document matrices. This structure can be exploited to give a more accurate updating scheme for LSI and to correct some of the misconception about the achievable retrieval accuracy in LSI updating. Variants of Lanczos algorithms are illustrated with numerical test results on Cray T3E using document collections generated from World Wide Web.
35264400
Parallel Efficiency of the Lanczos Method for Eigenvalue Problems
LBNL-42828 Parallel Efficiency of the Lanczos Method for Eigenvalue Problems ^ Kesheng Wu+and Horst Simon* Abstract Two of the commonly used versions of the Lanczos method for eigenvalues problems are the shift-and-invert Lanczos method and the restarted Lanczos method. In this talk, we will address two questions, is the shift-and-invert Lanczos method a viable option on massively parallel machines and which one is more appropriate for a given eigenvalue problem? Introduction T h i s talk is o n how to compute eigenvalues a n d eigenvectors of large sparse s y m m e t r i c matrices o n massively parallel machines. One of the the most c o m m o n l y used algorithms for this task is the Lanczos m e t h o d w h i c h projects the large eigenvalue p r o b l e m onto a low dimensional K r y l o v subspace [7, 10]. I n most cases, the K r y l o v subspace basis is built t h r o u g h a series of matrix-vector m u l t i p l i c a t i o n s , the whole Lanczos m e t h o d c a n be implemented w i t h a matrix-vector m u l t i p l i c a t i o n routine a n d a few simple vector operations. T h i s a l g o r i t h m is highly efficient on parallel machines a n d it is effective for c o m p u t i n g extreme a n d well separated eigenvalues. To compute the interior or not well-separated eigenvalues, the shift-and-invert Lanczos m e t h o d is one of the most effective methods. Since the eigenvalues of a m a t r i x A are related to the eigenvalues of (A — c r l ) by a simple relation X(A) = a + 1/X((A — c r l ) ) a n d the corresponding eigenvectors of A a n d (A — c r l ) are identical, the shift-and-invert scheme computes the extreme eigenvalues of (A — c r l ) a n d deduce the corresponding eigenvalues of A. W i t h appropriate choice of a, the extreme eigenvalues of (A — al)^ are well separated and can be easily computed. T h e shift-and-invert Lanczos m e t h o d needs to b u i l d a K r y l o v subspace basis of (A — c r l ) w h i c h is done by solving a series of linear systems involving the coefficient m a t r i x (A — a I). T h e linear systems need to be solved accurately a n d the only reliable means to accomplish this is by using a direct m e t h o d [5]. Because it is difficult to implement direct methods o n d i s t r i b u t e d parallel computers, efficient parallel i m p l e m e n t a t i o n has not been widely available u n t i l recently [1, 8]. T h i s talk w i l l present our s t u d y of the parallel efficiency of the shift-and-invert Lanczos m e t h o d using these newly available direct solvers. T h e study w i l l show that the shift-and-invert Lanczos m e t h o d is ' T h i s w o r k was s u p p o r t e d b y t h e D i r e c t o r , Office o f E n e r g y R e s e a r c h , Office o f L a b o r a t o r y P o l i c y a n d Infrastructure M a n a g e m e n t , of the U . S . D e p a r t m e n t of E n e r g y under C o n t r a c t N o . D E - A C 0 3 - 7 6 S F 0 0 0 9 8 . T h i s r e s e a r c h u s e d r e s o u r c e s o f t h e N a t i o n a l E n e r g y R e s e a r c h S c i e n t i f i c C o m p u t i n g C e n t e r , w h i c h is s u p p o r t e d b y t h e Office o f E n e r g y R e s e a r c h o f t h e U . S . D e p a r t m e n t o f E n e r g y . 'Lawrence Berkeley National Laboratory/NERSC, Berkeley, CA Email: {ksni, hdsimon}81bl.gov.
36271721
Industrial Application Areas of High-Performance Computing
In 1993, a list of the top 500 supercomputer sites worldwide was made available for the first time. Since then, the Top500 list has been published twice a year. The list allows a detailed and well-founded analysis of the state of high-performance computing (HPC). This article summarizes the recent trends in application areas of HPC systems, focusing on the increase in industrial installations and applications.
6977019
Rule Creation and Rule Learning Through Environmental Exploration
The task of learning from environment is specified. It requires the learner to infer the laws of the environment in terms of its percepts and actions, and use the laws to solve problems. Based on research on problem space creation and discrimination learning, this paper reports an approach in which exploration, rule creation and rule learning are coordinated in a single framework. With this approach, the system LIVE creates STRIPS-Iike rules by noticing the changes in the environment when actions are taken, and later refines the rules by explaining the failures of their predictions. Unlike many other learning systems, since LIVE treats learning and problem solving as interleaved activities, no training instance nor any concept hierarchy is necessary to start learning. Furthermore, the approach is capable of discovering hidden features from the environment when normal discrimination process fails to make any progress.
42465992
History of Artificial Intelligence
Though our discussion is e n t i t l e d "The History o f A r t i f i c i a l I n te l l i gence" , i n fac t we are focusing here on one b r i e f but h igh ly s i gn i f i can t moment in that h i s t o r y , the moment when a r t metamorphosed i t s e l f i n to science, from wish and dream to something l i k e r e a l i t y . As you w i l l learn from each of the discussants, th is metamorphosis took place at several locat ions during the ear ly to mid-1950s, and i t s ca ta lys t was the recogni t ion that the computer was the most promising medium yet in which to rea l i ze what had been a human dream since ea r l i es t t imes, the creat ion of man-made, rather than begotten i n te l l i gence .
206567160
Special Feature: Prometheus or Pandora: The Influence of Automation on Society
Even though computer technology may challenge one of man's last and most cherished illusions—that he alone is capable of thought—it can also show him how to live in harmony with nature.
20188177
Simulation of human verbal learning behavior
the eoinposition is or in not an ins:atl{'e of Arnohl 8el]oel/}}el,g>s so-ealhM "twelve-tone" system of l]ltb-:ieal eompositiol]. Wrilten ill a notation which modifies a notation for finite sequentia{ proces. ses developed /)y Kenneth It. lverso~:, che Mgori:hm in easily tra::slatatfle into most machine languages which allow processing of nlphanumerh: data. The decision process involved will be fully autolnatic when vharacter-recognitio~: maehiiws :hat "read" nlusi{'a/signs ape { mployed. A limited s::pply {}[ copies of lhe t)<~qter listed t>e]ow in available for distribution : The paper contains !he algorithm and a lengthy diseussi(m of issues r(lated to the synt'~c~i(~ properties of Schoenberg's system. A s s o c i a t i o n a l (' h a r a e t e r i s t i (: s o f ~I/()i'ds in T e x t S y s l (, m I)(~volopm(u~) (' o r p. , S a n t a M()l:i<l, (lalif. [i'cp(rl('d tilt; l,auPen B. I)oyle (t"et)iuiat'y 19(i2) An iuvestigation of the ten(teney {tf' words to eo..o(!e/iP in tl[li{,s of text (articles, Imragr,aphs, sentences) is continuing, with em-l)hasis on the eharaeteristies of strongly (o-oe(~urritlg op ":.tsso-elated" words. The ultimate chief.live of lho study i8 to eonfronl, litePalure searchers with usal}le representations (if text-derived associations which earl serve at least as automatically generated thesauri and at best as a.~sociative indexes. 'I'he most eonvelfient form for representing Such associations has been fotnid to lie di:> granmmtie or map-like {1!. Tile study is currently entering a new phase, in which the effect {m associations of varying the size and compost{ion of libraries is io be observed. For ihis purpose a PhiJco 2(}00 prograui is being written by which one ean flexibly deal with an unlimited number of libraries wifi0i: arc subsets of a given ~qiiastei" l i b r a r y " ; this avoids the necessity (if preparilig itew input for each rull on It different library. Library subsets to be processed can be specified either by control card or by programmed computation [2]. Further examples of the sort of study this program wil! facilitate are : (1) Automatic separation of homographs (e.g. in internatiolnal affairs "force" has a different meaning from "force" in physics; if a physics corptts can be automatically separated from one in international affairs, then homograph separation will oeetir in this ease). (2) Promotion of suppressed associations (i.e, two words wtiieh eo-oeeur …
206581413
A Time for Talk and a Time for Silence
The computer stores mountains of information which it communicates worldwide through an enormous bandwidth. We must learn to exercise severe, intelligent selectivity in mining our data mountains, and to communicate information in ways that will inform and not bury the recipients.