Atomicm-register operations

Summary We investigate systems where it is possible to access several shared registers in one atomic step. We characterize those systems in which the consensus problem can be solved in the presence of faults and give bounds on the space required. We also describe a fast solution to the mutual exclusion problem using atomicm-register operations. Michael Merritt received a B.S. degree in Philosophy and in Computer Science from Yale College in 1978, the M.S. and Ph. D. degrees in Information and Computer Science in 1980 and 1983, respectively, from the Georgia Institute of Technology. Since 1983 he has been a member of technical staff at AT&T Bell Laboratories, and has taught as an adjunct or visiting lecturer at Stevens Institute of Technology and Columbia University. In 1989 he was program chair for the ACM Symposium on Principles of Distributed Computing. His research interests include distributed and concurrent computation, both algorithms and formal methods for verifying their correctness, cryptography, and security. He is an editor for Distributed Computing and for Information and Computation, recently coauthored a book on database concurrency control algorithms, and is a member of the ACM and of Computer Professionals for Social Responsibility. Gadi Taubenfeld received the B.A., M.Sc. and Ph.D. degrees in Computer Science from the Technion (Israel Institute of Technology), in 1982, 1984 and 1988, respectively. From 1988 to 1990 he was a research scientist at Yale University. Since 1991 he has been a member of technical staff at AT&T Bell Laboratories. His primary research interests are in concurrent and distributed computing.A preliminary version of this workappeared in theProceedings of the Fifth International Workshop on Distributed Algorithms, Delphi, Greece, October 1991, pp 289–294     

Adaptive solutions to the mutual exclusion problem

Summary Algorithms for mutual exclusion that adapt to the current degree of contention are developed. Afilter and a leader election algorithm form the basic building blocks. The algorithms achieve system response times that are independent of the total number of processes and governed instead by the current degree of contention. The final algorithm achieves a constant amortized system response time. Manhoi Choy was born in 1967 in Hong Kong. He received his B.Sc. in Electrical and Electronic Engineerings from the University of Hong Kong in 1989, and his M.Sc. in Computer Science from the University of California at Santa Barbara in 1991. Currently, he is working on his Ph.D. in Computer Science at the University of California at Santa Barbara. His research interests are in the areas of parallel and distributed systems, and distributed algorithms. Ambuj K. Singh is an Assistant Professor in the Department of Computer Science at the University of California, Santa Barbara. He received a Ph.D. in Computer Science from the University of Texas at Austin in 1989, an M.S. in Computer Science from Iowa State University in 1984, and a B.Tech. from the Indian Institute of Technology at Kharagpur in 1982. His research interests are in the areas of adaptive resource allocation, concurrent program development, and distributed shared memory.A preliminary version of the paper appeared in the 12th Annual ACM Symposium on Principles of Distributed ComputingWork supported in part by NSF grants CCR-9008628 and CCR-9223094     

Static extensivity analysis for λ-definable functions over lattices

We employ a static analysis to examine the extensivity (∀x:x≤f(x)) of functions defined over lattices in a λ-calculus augmented with lattice operations. The need for such a verification procedure has arisen in our work on a generator system (called Zoo) of static program-analyzers. The input to Zoo is a static analysis specification that consists of lattice definitions and function definitions over the lattices. Once the extensivity of the functions is ascertained, the generated analyzer is guaranteed to terminate when the lattices have finite-heights. The extensivity analysis consists of a sound syntax-driven deductive rules whose satisfiability check is done by a constraint solving procedure. Hyunjun Eo: He is a Ph.D. candidate of Computer Science Dept. at KAIST (Korea Advanced Institute of Science and Technology). He received his B.S. and M.S. in Computer Science from KAIST in 1996 and 1998, respectively. For 1998–2003, he was a research assistant of the National Creative Research Initiative Center for Research On Program Analysis System. His research interest has been on static program analysis, program logics, and higher-order and typed languages. He is currently working on developing a tool for automatic generation of program analyzers. Kwangkeun Yi, Ph.D.: His research interest has been on semantic-based program analysis and systems application of language technologies. After his Ph.D. from University of Illinois at Urbana-Champaign he joined the Software Principles Research Department at Bell Laboratories, where he worked on various static analysis approaches for higher-order and typed programming languages. For 1995–2003, he was a faculty member in the Department of Computer Science, Korea Advanced Institute of Science and Technology. Since Fall 2003, he has been a faculty member in the School of Computer Science and Engineering, Seoul National University. Kwang-Moo Choe, Ph.D.: He is a professor of Computer Science at Korea Advanced Institute of Science and Technology. He received his B.S. from Seoul National University in 1976, and his M.S. and Ph.D. from Korea Advanced Institute of Science and Technology in 1978 and 1984, respectively. For 1985–1986, he was a technical staff of AT&T Bell Labs at Murray Hill. His research interest is formal language theory, parallel evaluation of logic programs, and optimizing compilers.     

Causal memory: definitions,implementation, and programming

Summary The abstraction of a shared memory is of growing importance in distributed computing systems. Traditional memory consistency ensures that all processes agree on a common order of all operations on memory. Unfortunately, providing these guarantees entails access latencies that prevent scaling to large systems. This paper weakens such guarantees by definingcausal memory, an abstraction that ensures that processes in a system agree on the relative ordering of operations that arecausally related. Because causal memory isweakly consistent, it admits more executions, and hence more concurrency, than either atomic or sequentially consistent memories. This paper provides a formal definition of causal memory and gives an implementation for message-passing systems. In addition, it describes a practical class of programs that, if developed for a strongly consistent memory, run correctly with causal memory. Mustaque Ahamad is an Associate Professor in the College of Computing at the Georgia Institute of Technology. He received his M.S. and Ph.D. degrees in Computer Science from the State University of New York at Stony Brook in 1983 and 1985 respectively. His research interests include distributed operating systems, consistency of shared information in large scale distributed systems, and replicated data systems. James E. Burns received the B.S. degree in mathematics from the California Institute of Technology, the M.B.I.S. degree from Georgia State University, and the M.S. and Ph.D. degrees in information and computer science from the Georgia Institute of Technology. He served on the faculty of Computer Science at Indiana University and the College of Computing at the Georgia Institute of Technology before joining Bellcore in 1993. He is currently a Member of Technical Staff in the Network Control Research Department, where he is studying the telephone control network with special interest in behavior when faults occur. He also has research interests in theoretical issues of distributed and parallel computing especially relating to problems of synchronization and fault tolerance.This work was supported in part by the National Science Foundation under grants CCR-8619886, CCR-8909663, CCR-9106627, and CCR-9301454. Parts of this paper appeared in S. Toueg, P.G. Spirakis, and L. Kirousis, editors,Proceedings of the Fifth International Workshop on Distributed Algorithms, volume 579 ofLecture Notes on Computer Science, pages 9–30, Springer-Verlag, October 1991The photograph of Professor J.E. Burns was published in Volume 8, No. 2, 1994 on page 59This author's contributions were made while he was a graduate student at the Georgia Institute of Technology. No photograph and biographical information is available for P.W. Hutto Gil Neiger was born on February 19, 1957 in New York, New York. In June 1979, he received an A.B. in Mathematics and Psycholinguistics from Brown University in Providence, Rhode Island. In February 1985, he spent two weeks picking cotton in Nicaragua in a brigade of international volunteers. In January 1986, he received an M.S. in Computer Science from Cornell University in Ithaca, New York and, in August 1988, he received a Ph.D. in Computer Science, also from Cornell University. On August 20, 1988, Dr. Neiger married Hilary Lombard in Lansing, New York. He is currently a Staff Software Engineer at Intel's Software Technology Lab in Hillsboro, Oregon. Dr. Neiger is a member of the editorial boards of theChicago Journal of Theoretical Computer Science and theJournal of Parallel and Distributed Computing.     

Proofs of a set of hybrid let-polymorphic type inference algorithms

We present a generalized let-polymorphic type inference algorithm, prove that any of its instances is sound and complete with respect to the Hindley/Milner let-polymorphic type system, and find a condition on two instance algorithms so that one algorithm should find type errors earlier than the other. By instantiating the generalized algorithm with different parameters, we can obtain not only the two opposite algorithms (the bottom-up standard algorithmW and the top-down algorithmM) but also other hybrid algorithms which are used in real compilers. Such instances’ soudness and completeness follow automatically, and their relative earliness in detecting type-errors is determined by checking a simple condition. The set of instances of the generalized algorithm is a superset of those used in the two most popular ML compilers: SML/NJ and OCaml. This work is supported by Creative Research Initiatives of the Korean Ministry of Science and Technology National Creative Research Initiative Center, http://ropas.kaist.ac.kr Work done while the third author was associated with Korea Advanced Institute of Science and Technology Hyunjun Eo: He is a Ph.D. candidate in the Department of Computer Science at KAIST (Korea Advanced Institute of Science and Technology). He recieved his bachelor’s degree and master’s degree in Computer Science from KAIST in 1996 and 1998, respectively. His research interest has been on static program analysis, fixpoint iteration algorithm and higher-order and typed languages. From fall 1998, he has been a research assistant of the National Creative Research Initiative Center for Research on Program Analysis System. He is currently working on developing a tool for automatic generation of program analyzer. Oukseh Lee: He is a Ph.D. candidate in the Department of Computer Science at KAIST (Korea Advanced Institute of Science and Technology). He received his bachelor’s and master’s degree in Computer Science from KAIST in 1995 and 1997, respectively. His research interest has been on static program analysis, type system, program language implementation, higher-order and typed languages, and program verification. From 1998, he has been a research assistant of the National Creative Research Initiative Center for Research on Program Analysis System. He is currently working on compile-time analyses and verification for the memory behavior of programs. Kwangkeun Yi, Ph.D.: His research interest has been on semanticbased program analysis and systems application of language technologies. After his Ph.D. from University of Illinois at Urbana-Champaign he joined the Software Principles Research Department at Bell Laboratories, where he worked on various static analysis approaches for higher-order and typed programming languages. For 1995 to 2003 he was a faculty member in the Department of Computer Science, Korea Advanced Institute of Science and Technology. Since fall 2003, he has been a faculty member in the School of Computer Science and Engineering, Seoul National University.     

Easy impossibility proofs for distributed consensus problems

Easy proofs are given, of the impossibility of solving several consensus problems (Byzantine agreement, weak agreement, Byzantine firing squad, approximate agreement and clock synchronization) in certain communication graphs.It is shown that, in the presence ofm faults, no solution to these problems exists for communication graphs with fewer than 3m+1 nodes or less than 2m+1 connectivity. While some of these results had previously been proved, the new proofs are much simpler, provide considerably more insight, apply to more general models of computation, and (particularly in the case of clock synchronization) significantly strengthen the results.Michael J. Fischer is currently Professor of Computer Science at Yale University, New Haven, CT, where he heads the Theory of Computation Group. He is also Editor-in-Chief of the Journal of the Association for Computing Machinery. His research interests include theory of distributed systems, cryptographic protocols, and computational complexity.Dr. Fischer received the B. S. degree in matheamtics from the University of Michigan, Ann Arbor, in 1963, and the M. A. and Ph. D. degrees in applied mathematics from Harvard University, Cambridge, MA, in 1965 and 1968, respectively. He has taught previously at Carnegie-Mellon University, the Massachusetts Institute of Technology, and University of Washington.Nancy Lynch is currently Associate professor of Computer Science at M.I.T., and heads the Theory of Distributed Systems group in M.I.T.'s Laboratory for Computer Science. Her interests are in all aspects of distributed computing theory, including formal models, algorithms, analysis, and correctness proofs. Dr. Lynch received the B.S. degree in mathematics from Brooklyn College in 1968 and the Ph. D. degree in mathematics from M.I.T. in 1972. She has served on the faculty of Tufts University, the University of Southern California, Florida International University, Georgia Tech.Michael Merritt is currently a member of the technical staff with AT&T Bell Laboratories. During the 1984 –85 academic year, he was a visiting lecturer at M.I.T., sponsered by Bell Labs. His research interests include distributed computation, cryptography and security. Dr. Merritt received the B. S. degree in computer science and philosophy from Yale in 1978 and the M. Sc. and Ph. D. degrees in 1980 and 1983, respectively, both in information and computer science from Georgia Tech. He is a member of SIGACT and of Computer Professionals for Social Responsibility.This paper has appeared in the ACM Conference Proceedings of PODC 1985. © 1985, Association for Computing Machinery, reprinted by permission     

Test Resource Partitioning Based on Efficient Response Compaction for Test Time and Tester Channels Reduction

This paper presents a test resource partitioning technique based on an efficient response compaction design called quotient compactor(q-Compactor). Because q-Compactor is a single-output compactor, high compaction ratios can be obtained even for chips with a small number of outputs. Some theorems for the design of q-Compactor are presented to achieve full diagnostic ability, minimize error cancellation and handle unknown bits in the outputs of the circuit under test (CUT). The q-Compactor can also be moved to the load-board, so as to compact the output response of the CUT even during functional testing. Therefore, the number of tester channels required to test the chip is significantly reduced. The experimental results on the ISCAS ‘89 benchmark circuits and an MPEG 2 decoder SoC show that the proposed compactionscheme is very efficient.     

Transaction commit in a realistic timing model

Animportant problem in the construction of fault-tolerant distributed database systems is the design of nonblocking transaction commit protocols. This problem has been extensively studied for synchronous systems (i.e., systems where no messages ever arrive late). In this paper, the synchrony assumption is relaxed. A new partially synchronous timing model is described. Developed for this model is a new nonblocking randomized transaction commit protocol, which incorporates an agreement protocol of Ben-Or. The new protocol works as long as fewer than half the processors fail. A matching lower bound is proved, showing that the number of processor faults tolerated is optimal. If half or more of the processors fail, the protocol degrades gracefully: it blocks, but no processor produces a wrong answer. A notion of asynchronous round is defined, and the protocol is shown to terminate in a small constant expected number of asynchronous rounds. In contrast it is shown that no protocol in this model can guarantee that a processor terminates in a bounded expected number of its own steps, even if processors are synchronous. Brian A. Coan received the B.S.E. degree in electrical engineering and computer science from Princeton University, Princeton, New Jersey, in 1977; the M.S. degree in computer engineering from Stanford University, Stanford, California, in 1979; and the Ph.D. degree in computer science from the Massachusetts Institute of Technology, Cambridge, Massachusetts, in 1987. He has worked for Amdahl Corporation and AT & T Bell Laboratories. Currently he is a member of the technical staff at Bellcore. His main research interest is fault tolerance in distributed systems. Jennifer Lundelius Welch received her B.A. in 1979 from the University of Texas at Austin, and her S.M. and Ph.D. from the Massachusetts Institute of Technology in 1984 and 1988 respecively. She was a member of technical staff at GTE Laboratories Incorporated in Waltham, Massachusetts, from 1988 to 1989. She is currently an assistant professor at the University of North Carolina in Chapel Hill. Her research interests include algorithms and lower bounds for distributed computing.The authors were with the MIT Laboratory for Computer Science when the bulk of this work was done. This work was supported in part by the Advanced Research Projects Agency of the Department of Defense under Contract N00014-83-K-0125, the National Science Foundation under Grant DCR-83-02391, the Office of Army Research under Contract DAAG29-84-K-0058, and the Office of Naval Research under Contract N00014-85-K-0168. A preliminary version of this paper appears in theProceedings of the Fifth Annual ACM Symposium on Principles of Distributed Computing [2]     

Self-stabilization of dynamic systems assuming only read/write atomicity

Summary Three self-stabilizing protocols for distributed systems in the shared memory model are presented. The first protocol is a mutual-exclusion prootocol for tree structured systems. The second protocol is a spanning tree protocol for systems with any connected communication graph. The thrid protocol is obtianed by use offair protoco combination, a simple technique which enables the combination of two self-stabilizing dynamic protocols. The result protocol is a self-stabilizing, mutualexclusion protocol for dynamic systems with a general (connected) communication graph. The presented protocols improve upon previous protocols in two ways: First, it is assumed that the only atomic operations are either read or write to the shared memory. Second, our protocols work for any connected network and even for dynamic network, in which the topology of the network may change during the excution. Shlomi Dolev received his B.Sc. in Civil Engineering and B.A. in Computer Science in 1984 and 1985, and his M.Sc. and Ph.D. in computer Sciene in 1989 and 1992 from the Technion Israel Institute of Technology. He is currently a post-dotoral fellow in the Department of Computer Science at Texas A & M Univeristy. His current research interests include the theoretical aspects of distributed computing and communcation networks. Amos Israeli received his B.Sc. in Mathematics and Physics from Hebrew University in 1976, and his M.Sc. and D.Sc. in Computer Science from the Weizmann Institute in 1980 and the Technion in 1985, respectively. Currently he is a sensior lecturer at the Electrical Engineering Department at the Technion. Prior tot his he was a postdoctoral fellow at the Aiken Computation Laboratory at harvard. His research interests are in Parellel and Distributed Computing and in Robotics. In particular he has worked on the design and analysis of Wait-Free and Self-Stabilizing distributed protocols. Shlomo Moran received his B.Sc. and D.Sc. degrees in matheamtics from Technion, Israel Institute of Technology, Haifa, in 1975 and 1979, respectively. From 1979 to 1981 he was assistant professors and a visiting research specialist at the University of Minnesota, Minneapolis. From 1981 to 1985 he was a senior lecturer at the Department of Computer Science. Technion, and from 1985 to 1986 he visted at IBM Thoas J. Watson Research Center, Yorktown Heights. From 1986 to 1993 he was an associated professor at the Department of Computer Science, Technin. in 1992–3 he visited at AT & T Bell Labs at Murray Hill and at Centrum voor Wiskunde en Informatica, Amsterdam. From 1993 he is a full professor at the Department of Computer Science, Technion. His researchinterests include distributed algorithm, computational complexity, combinatorics and grapth theory.Part of this research was supported in part by Technion V.P.R. Funds — Wellner Research Fund, and by the Foundation for Research in Electronics, Computers and Communictions, administrated by the Israel Academy of Sciences and Humanities.     

Fast and simple distributed consensus

Summary The problem of fault-tolerant agreement is fundamental to distributed computing. When agreement is to be reached in spite of arbitrary behavior by faulty processors, this problem is calledDistributed Consensus. By requiring that the number of faulty processors be , wheren is the number of processors in the system, we are able to derive two new protocols forDistributed Consensus. Both are simple and use messages that are only one bit in length, and both provide forearly stopping: the fewer failures there are, the fewer rounds of communication are required. One protocol is optimal with respect to the number of rounds of communication required, and the other is asymptotically optimal with respect to the total number of message bits exchanged. James E. Burns received the B.S. degree in mathematics from the California Institute of Technology, the M.B.I.S. degree from Georgia State University, and the M.S. and Ph.D. degrees in information and computer science from the Georgia Institute of Technology. He served on the faculty of Computer Science at Indiana University and the College of Computing at the Georgia Institute of Technology before joining Bellcore in 1993. He is currently a Member of Technical Staff in the Network Control Research Department, where he is studying the telephone control network with special interest in behavior when faults occur. He also has research interests in theoretical issues of distributed and parallel computing, especially relating to problems of synchronization and fault tolerance. Gil Neiger was born on February 19, 1957 in New York, New York. In June 1979, he received an A.B. in Mathematics and Psycholinguistics from Brown University in Proidence, Rhode Island. In February 1985, he spent two weeks picking cotton in Nicaragua in a brigade of international volunteers. In January 1986, he received an M.S. in Computer Science from Cornell University in Ithaca, New York and, in August 1988, he received a Ph.D. in Computer Science, also from Cornell University. On August 20, 1988, Dr. Neiger married Hilary Lombard in Lansing, New York. Since August 1988, he has been an Assistant Professor in the College of Computing (formely School of Information and Computer Science) at the Georgia Institute of Technology in Atlanta, Georgia. Dr. Neiger is a member of the editorial board of theChicago Journal of Theoretical Computer Science and theJournal of Parallel and Distributed Computing.This author was supported in part by the National Science Foundation under grants CCR-8909663, CCR-9106627, and CCR-9301454.     

A fast,scalable mutual exclusion algorithm

Summary This paper is concerned with synchornization under read/write atomicity in shared memory multi-processors. We present a new algorithm forN-process mutual exclusion that requires only read and write operations and that hasO(logN) time complexity, where time is measured by counting remote memory references. The time complexity of this algorithm is better than that of all prior solutions to the mutual exclusion problem that are based upon atomic read and write instructions; in fact, the time complexity of most prior solutions is unbounded. Performance studies are presented that show that our mutual exclusion algorithm exhibits scalable performance under heavy contention. In fact, its performance rivals that of the fastest queue-based spin locks based on strong primitives such as compare-and-swap and fetch-and-add. We also present a modified version of our algorithm that generates onlyO(1) memory references in the absence of contention. Jae-Heon Yang received the B.S. and M. S. degrees in Computer Engineering from Seoul National University in 1985 and 1987, respectively, and the Ph.D. degree in Computer Science from the University of Maryland at College Park in 1994. Since June 1994, he has been an Assistant Professor of Computer Science at Mills College in Oakland, California. From 1987 to 1989, he was a junior researcher at the Korea Telecommunication Authority Research Center. His research interests include distributed computing and operating systems. James H. Anderson received the M. S. degree in Computer Science from Michigan State University in 1982, the M.S. degree in Computer Science from Purdue University in 1983, and the Ph.D. degree in Computer Sciences from the University of Texas at Austin in 1990. Since August 1993, he has been an Assistant Professor of Computer Science at the University of North Carolina at Chapel Hill. Prior to joining the University of North Carolina, he was an Assistant Professor of Computer Science for three years at the University of Maryland at College Park Professor Anderson's main research interests are within the area of coneurrent and distributed computing. His current interests include wait-free algorithms, scalabde synchronization mechanisms for shared-memory systems, and object-sharing strategies for hard real-time applications.Preliminary version was presented at the Twelfth Annual ACM Symposium on Principles of Distributed Computing Ithaca, New York, August 1993 [15]. Work supported, in part, by NSF Contracts CCR-9109497 and CCR-9216421 and by the Center for Excellence in Space Data and Information Sciences (CESDIS)     

GigaE PM: a high performance communication facility using a Gigabit Ethernet

A high performance communication facility, called theGigaE PM, has been designed and implemented for parallel applications on clusters of computers using a Gigabit Ethernet. The GigaE PM provides not only a reliable high bandwidth and low latency communication, but also supports existing network protocols such as TCP/IP. A reliable communication mechanism for a parallel application is implemented on the firmware on a NIC while existing network protocols are handled by an operating system kernel. A prototype system has been implemented using an Essential Communications Gigabit Ethernet card. The performance results show that a 58.3 μs round trip time for a four byte user message, and 56.7 MBytes/sec bandwidth for a 1,468 byte message have been achieved on Intel Pentium II 400 MHz PCs. We have implemented MPICH-PM on top of the GigaE PM, and evaluated the NAS parallel benchmark performance. The results show that the IS class S performance on the GigaE PM is 1.8 times faster than that on TCP/IP. Shinji Sumimoto: He is a Senior Researcher of Parallel and Distributed System Software Laboratory at Real World Computing Partnership, JAPAN. He received BS degree in electrical engineering from Doshisha University. His research interest include parallel and distributed systems, real-time systems, and high performance communication facilities. He is a member of Information Processing Society of Japan. Hiroshi Tezuka: He is a Senior Researcher of Parallel and Distributed System Software Laboratory at Real World Computing Partnership, JAPAN. His research interests include real-time systems and operating system kernel. He is a member of the Information Processing Society of Japan, and Japan Society for Software Science and Technology. Atsushi Hori, Ph.D.: He is a Senior Researcher of Parallel and Distributed System Software Laboratory at Real World Computing Partnership, JAPAN. His current research interests include parallel operating system. He received B.S. and M.S. degrees in Electrical Engineering from Waseda University, and received Ph.D. from the University of Tokyo. He worked as a researcher in Mitsubishi Research Institute from 1981 to 1992. Hiroshi Harada: He is a Senior Researcher of Parallel and Distributed System Software Laboratory at Real World Computing Partnership, JAPAN. His research interests include distributed/parallel systems and distributed shared memory. He received BS degree in physics from Science University of Tokyo. He is a member of ACM and Information Processing Society of Japan. Toshiyuki Takahashi: He is a Researcher at Real World Computing Partnership since 1998. He received his B.S. and M.S. from the Department of Information Sciences of Science University of Tokyo in 1993 and 1995. He was a student of the Information Science Department of the University of Tokyo from 1995 to 1998. His current interests are in meta-level architecture for programming languages and high-performance software technologies. He is a member of Information Processing Society of Japan. Yutaka Ishikawa, Ph.D.: He is the chief of Parallel and Distributed System Software Laboratory at Real World Computing Partnership, JAPAN. He is currently temporary retirement from Electrotechnical Laboratory, MITI. His research interests include distributed/parallel systems, object-oriented programming languages, and real-time systems. He received the B.S., M.S. and Ph.D degrees in electrical engineering from Keio University. He is a member of the IEEE Computer Society, ACM, Information Processing Society of Japan, and Japan Society for Software Science and Technology.     

Composite registers

Summary We introduce a shared data object, called acomposite register, that generalizes the notion of an atomic register. A composite register is an array-like shared data object that is partitioned into a number of components. An operation of a composite register either writes a value to a single component or reads the values of all components. A composite register reduces to an ordinary atomic register when there is only one component. In this paper, we show that multi-reader, singlewriter atomic registers can be used to implement a composite register in which there is only one writer per component. In a related paper, we show how to use the composite register construction of this paper to implement a composite register with multiple writers per component. These two constructions show that it is possible to implement a shared memory that can be read in its entirety in a single snapshot operation, without using mutual exclusion. James H. Anderson received the B.S. degree in Computer Science from Michigan State University in 1982, the M.S. degree in Computer Science from Purdue University in 1983, and the Ph.D. degree in Computer Sciences from the University of Texas at Austin in 1990. Since August 1990, he has been with the University of Maryland at College Park, where he is now an Assistant Professor of Computer Science. Since January 1992, he has been a staff scientist at NASA's Center of Excellence in Space Data and Information Sciences, located at the Goddard Space Flight Center in Greenbelt, Maryland. Professor Anderson's primary research interests are within the area of concurrent and distributed computing.Preliminary version presented at theNinth Annual ACM Symposium on Principles of Distributed Computing [2]Work supported, in part, at the University of Texas at Austin by Office of Naval Research Contract N00014-89-J-1913, and at the University of Maryland by an award from the University of Maryland General Research Board     

Multi-writer composite registers

Summary Acomposite register is an array-like shared data object that is partitioned into a number of components. An operation of such a register either writes a value to a single component, or reads the values of all components. A composite register reduces to an ordinary atomic register when there is only one component. In this paper, we show that a composite register with multiple writers per component can be implemented in a wait-free manner from a composite register with a single writer per component. It has been previously shown that registers of the latter kind can be implemented from atomic registers without waiting. Thus, our results establish that any composite register can be implemented in a wait-free manner from atomic registers. We show that our construction has comparable space compexity and better time complexity than other constructions that have been presented in the literature. James H. Anderson received the B.S. degree in Computer Science from Michigan State University in 1982, the M.S. degree in Computer Science from Purdue University in 1983, and the Ph.D. degree in Computer Sciences from the University of Texas at Austin in 1990. He recently joined the Computer Science Department at the University of North Carolina at Chapel Hill, where he is now an Assistant Professor. Prior to joining the University of North Carolina, he was an Assistant Professor of Computer Science for three years at the University of Maryland at College Park. Professor Anderson's main research interests are within the area of concurrent and distributed computing. His current interests primarily involve the implementation of resilient and scalable synchronization mechanisms.Preliminary version was presented at the Ninth Annual ACM Symposium on Principles of Distributed Computing [2]Much of the work described herein was completed while the author was with the University of Texas at Austin and the University of Maryland at College Park. This work was supported at the University of Texas by ONR Contract N00014-89-J-1913, and at the University of Maryland by NSF Contract CCR 9109497 and by an award from the University of Maryland General Research Board     

A study of the model and algorithms for handling location-dependent continuous queries

Advances in wireless and mobile computing environments allow a mobile user to access a wide range of applications. For example, mobile users may want to retrieve data about unfamiliar places or local life styles related to their location. These queries are called location-dependent queries. Furthermore, a mobile user may be interested in getting the query results repeatedly, which is called location-dependent continuous querying. This continuous query emanating from a mobile user may retrieve information from a single-zone (single-ZQ) or from multiple neighbouring zones (multiple-ZQ). We consider the problem of handling location-dependent continuous queries with the main emphasis on reducing communication costs and making sure that the user gets correct current-query result. The key contributions of this paper include: (1) Proposing a hierarchical database framework (tree architecture and supporting continuous query algorithm) for handling location-dependent continuous queries. (2) Analysing the flexibility of this framework for handling queries related to single-ZQ or multiple-ZQ and propose intelligent selective placement of location-dependent databases. (3) Proposing an intelligent selective replication algorithm to facilitate time- and space-efficient processing of location-dependent continuous queries retrieving single-ZQ information. (4) Demonstrating, using simulation, the significance of our intelligent selective placement and selective replication model in terms of communication cost and storage constraints, considering various types of queries. Manish Gupta received his B.E. degree in Electrical Engineering from Govindram Sakseria Institute of Technology & Sciences, India, in 1997 and his M.S. degree in Computer Science from University of Texas at Dallas in 2002. He is currently working toward his Ph.D. degree in the Department of Computer Science at University of Texas at Dallas. His current research focuses on AI-based software synthesis and testing. His other research interests include mobile computing, aspect-oriented programming and model checking. Manghui Tu received a Bachelor degree of Science from Wuhan University, P.R. China, in 1996, and a Master's Degree in Computer Science from the University of Texas at Dallas 2001. He is currently working toward the Ph.D. degree in the Department of Computer Science at the University of Texas at Dallas. Mr. Tu's research interests include distributed systems, wireless communications, mobile computing, and reliability and performance analysis. His Ph.D. research work focuses on the dependent and secure data replication and placement issues in network-centric systems. Latifur R. Khan has been an Assistant Professor of Computer Science department at University of Texas at Dallas since September 2000. He received his Ph.D. and M.S. degrees in Computer Science from University of Southern California (USC) in August 2000 and December 1996, respectively. He obtained his B.Sc. degree in Computer Science and Engineering from Bangladesh University of Engineering and Technology, Dhaka, Bangladesh, in November of 1993. Professor Khan is currently supported by grants from the National Science Foundation (NSF), Texas Instruments, Alcatel, USA, and has been awarded the Sun Equipment Grant. Dr. Khan has more than 50 articles, book chapters and conference papers focusing in the areas of database systems, multimedia information management and data mining in bio-informatics and intrusion detection. Professor Khan has also served as a referee for database journals, conferences (e.g. IEEE TKDE, KAIS, ADL, VLDB) and he is currently serving as a program committee member for the 11th ACM SIGKDD International Conference on Knowledge Discovery and Data Mining (SIGKDD2005), ACM 14th Conference on Information and Knowledge Management (CIKM 2005), International Conference on Database and Expert Systems Applications DEXA 2005 and International Conference on Cooperative Information Systems (CoopIS 2005), and is program chair of ACM SIGKDD International Workshop on Multimedia Data Mining, 2004. Farokh Bastani received the B.Tech. degree in Electrical Engineering from the Indian Institute of Technology, Bombay, and the M.S. and Ph.D. degrees in Computer Science from the University of California, Berkeley. He is currently a Professor of Computer Science at the University of Texas at Dallas. Dr. Bastani's research interests include various aspects of the ultrahigh dependable systems, especially automated software synthesis and testing, embedded real-time process-control and telecommunications systems and high-assurance systems engineering. Dr. Bastani was the Editor-in-Chief of the IEEE Transactions on Knowledge and Data Engineering (IEEE-TKDE). He is currently an emeritus EIC of IEEE-TKDE and is on the editorial board of the International Journal of Artificial Intelligence Tools, the International Journal of Knowledge and Information Systems and the Springer-Verlag series on Knowledge and Information Management. He was the program cochair of the 1997 IEEE Symposium on Reliable Distributed Systems, 1998 IEEE International Symposium on Software Reliability Engineering, 1999 IEEE Knowledge and Data Engineering Workshop, 1999 International Symposium on Autonomous Decentralised Systems, and the program chair of the 1995 IEEE International Conference on Tools with Artificial Intelligence. He has been on the program and steering committees of several conferences and workshops and on the editorial boards of the IEEE Transactions on Software Engineering, IEEE Transactions on Knowledge and Data Engineering and the Oxford University Press High Integrity Systems Journal. I-Ling Yen received her B.S. degree from Tsing-Hua University, Taiwan, and her M.S. and Ph.D. degrees in Computer Science from the University of Houston. She is currently an Associate Professor of Computer Science at University of Texas at Dallas. Dr. Yen's research interests include fault-tolerant computing, security systems and algorithms, distributed systems, Internet technologies, E-commerce and self-stabilising systems. She has published over 100 technical papers in these research areas and received many research awards from NSF, DOD, NASA and several industry companies. She has served as Program Committee member for many conferences and Program Chair/Cochair for the IEEE Symposium on Application-Specific Software and System Engineering & Technology, IEEE High Assurance Systems Engineering Symposium, IEEE International Computer Software and Applications Conference, and IEEE International Symposium on Autonomous Decentralized Systems. She has also served as a guest editor for a theme issue of IEEE Computer devoted to high-assurance systems.     

Design and analysis of the Dual-Torus Network

In this paper, we propose a new topology called theDual Torus Network (DTN) which is constructed by adding interleaved edges to a torus. The DTN has many advantages over meshes and tori such as better extendibility, smaller diameter, higher bisection width, and robust link connectivity. The most important property of the DTN is that it can be partitioned into sub-tori of different sizes. This is not possible for mesh and torus-based systems. The DTN is investigated with respect to allocation, embedding, and fault-tolerant embedding. It is shown that the sub-torus allocation problem in the DTN reduces to the sub-mesh allocation problem in the torus. With respect to embedding, it is shown that a topology that can be embedded into a mesh with dilation δ can also be embedded into the DTN with less dilation. In fault-tolerant embedding, a fault-tolerant embedding method based on rotation, column insertion, and column skip is proposed. This method can embed any rectangular grid into its optimal square DTN when the number of faulty nodes is fewer than the number of unused nodes. In conclusion, the DTN is a scalable topology well-suited for massively parallel computation. Sang-Ho Chae, M.S.: He received the B.S. in the Computer Science and Engineering from the Pohang University of Science and Technology (POSTECH) in 1994, and the M.E. in 1996. Since 1996, he works as an Associate Research Engineer in the Central R&D Center of the SK Telecom Co. Ltd. He took part in developing SK Telecom Short Message Server whose subscribers are now over 3.5 million and Advanced Paging System in which he designed and implemented high availability concepts. His research interests are the Fault Tolerance, Parallel Processing, and Parallel Topolgies. Jong Kim, Ph.D.: He received the B.S. degree in Electronic Engineering from Hanyang University, Seoul, Korea, in 1981, the M.S. degree in Computer Science from the Korea Advanced Institute of Science and Technology, Seoul, Korea, in 1983, and the Ph.D. degree in Computer Engineering from Pennsylvania State University, U.S.A., in 1991. He is currently an Associate Professor in the Department of Computer Science and Engineering, Pohang University of Science and Technology, Pohang, Korea. Prior to this appointment, he was a research fellow in the Real-Time Computing Laboratory of the Department of Electrical Engineering and Computer Science at the University of Michigan from 1991 to 1992. From 1983 to 1986, he was a System Engineer in the Korea Securities Computer Corporation, Seoul, Korea. His major areas of interest are Fault-Tolerant Computing, Performance Evaluation, and Parallel and Distributed Computing. Sung Je Hong, Ph.D.: He received the B.S. degree in Electronics Engineering from Seoul National University, Korea, in 1973, the M.S. degree in Computer Science from Iowa State University, Ames, U.S.A., in 1979, and the Ph.D. degree in Computer Science from the University of Illinois, Urbana, U.S.A., in 1983. He is currently a Professor in the Department of Computer Science and Engineering, Pohang University of Science and Technology, Pohang, Korea. From 1983 to 1989, he was a staff member of Corporate Research and Development, General Electric Company, Schenectady, NY, U.S.A. From 1975 to 1976, he was with Oriental Computer Engineering, Korea, as a Logic Design Engineer. His current research interest includes VLSI Design, CAD Algorithms, Testing, and Parallel Processing. Sunggu Lee, Ph.D.: He received the B.S.E.E. degree with highest distinction from the University of Kansas, Lawrence, in 1985 and the M.S.E. and Ph.D. degrees from the University of Michigan, Ann Arbor, in 1987 and 1990, respectively. He is currently an Associate Professor in the Department of Electronic and Electrical Engineering at the Pohang University of Science and Technology (POSTECH), Pohang, Korea. Prior to this appointment, he was an Associate Professor in the Department of Electrical Engineering at the University of Delaware in Newark, Delaware, U.S.A. From June 1997 to July 1998, he spent one year as a Visiting Scientist at the IBM T. J. Watson Research Center. His research interests are in Parallel, Distributed, and Fault-Tolerant Computing. Currently, his main research focus is on the high-level and low-level aspects of Inter-Processor Communications for Parallel Computers.     

Stabilization and pseudo-stabilization

Summary Astabilizing system is one which if started at any state is guaranteed to reach a state after which the system cannot deviate from its intended specification. In this paper, we propose a new variation of this notion, called pseudo-stabilization. Apseudo-stabilizing system is one which if started at any state is guaranteed to reach a state after which the system does not deriate from its intended specification. Thus, the difference between the two notions comes down to the difference between cannot and does not — a difference that hardly matters in many practical situations. As it happens, a number of well-known systems, for example the alternating-bit protocol, are pseudo-stabilizing but not stabilizing. We conclude that one should not try to make any such system stabilizing, especially if stabilization comes at a high price. James E. Burns received the B.S. degree in mathematics from the California Institute of Technology, the M.B.I.S. degree from Georgia State University, and the M.S. and Ph.D. degrees in information and computer science from the Georgia Institute of Technology. He is currently an Associate Professor in the College of Computing at the Georgia Institute of Technology, having served previously on the faculty at Indiana University. He has broad research in theoretical issues of distributed and parallel computing, especially relating to problems of synchronization and fault tolerance. Mohamed Gawdat Gouda was born and raised in Egypt. His first bachelor degree was in engineering, and his second was in mathematics. Both degrees are from Cairo University. After his graduation, he moved to Canada where he obtained an MA in mathematics from York University, and a Master and a Ph.D. in computing science from the University of Waterloo. Later, he moved to the United states of America where he worked for the Honeywell Corporate Technology Center for three years. In 1980, he moved to the University of Texas at Austin, and has settled there ever since, except for one summer at Bell Labs, one summer at MCC, and one winter at the Eindhoven Technical University. Gouda currently holds the Mike A. Myer Centennial Professorship in Computing Science at the University of Texas at Austin. Gouda's area of research is distributed and concurrent computing. In this area, he has been working on: abstraction, nondeterminism, atomicity, convergence, stability, formality, correctness, efficiency, scientific elegance, and technical beauty (not necesarily in that order). Gouda was the founding Editor-in-Chief of the journal Distributed Computing, published by Springer-Verlag in 1985. He was the program committee chairman of the 1989 SIGCOMM Conference sponsored by ACM. He was the first program committee chairman for the International Conference on Network Protocols, established by the IEEE Computer Society in 1993. Gouda is an original member of the Austin Tuesday Afternoon Club. In his spare time, he likes to design network protocols and prove them correct for fun. Raymond E. Miller received his Ph.D. in 1957 from the University of Illinois, Champaign-Urbana. He was a Research Staff Member at IBM, Thomas J. Watson Research Center, Yorktown Heights, N.Y., from 1957 until 1980, Director of the School of Information and Computer Science at Georgia Tech from 1980 until 1987, and is currently a professor of computer science at the University of Maryland, College Park and Director of the NASA Center of Excellence in Space Data and Information Sciences at Goddard Space Flight Center. He has written over 90 technical papers in areas of theory of computation, machine organization, parellel computation and communication protocols. He is a Fellow of the IEEE and a Fellow of the American Association for the Advancement of Science. He has been active in the ACM and IEE/CS, and is a Board member of the Computing Research Association. In the IEEE/CS, he is a member of the Board of Governors and the 1991 Vice President for Educational Activities.     

Scheduling real-time requests in on-demand data broadcast environments

On-demand broadcast is an attractive data dissemination method for mobile and wireless computing. In this paper, we propose a new online preemptive scheduling algorithm, called PRDS that incorporates urgency, data size and number of pending requests for real-time on-demand broadcast system. Furthermore, we use pyramid preemption to optimize performance and reduce overhead. A series of simulation experiments have been performed to evaluate the real-time performance of our algorithm as compared with other previously proposed methods. The experimental results show that our algorithm substantially outperforms other algorithms over a wide range of workloads and parameter settings. The work described in this paper was partially supported by grants from CityU (Project No. 7001841) and RGC CERG Grant No. HKBU 2174/03E. This paper is an extended version of the paper “A preemptive scheduling algorithm for wireless real-time on-demand data broadcast” that appeared in the 11th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications. Victor C. S. Lee received his Ph.D. degree in Computer Science from the City University of Hong Kong in 1997. He is now an Assistant Professor in the Department of Computer Science of the City University of Hong Kong. Dr. Lee is a member of the ACM, the IEEE and the IEEE Computer Society. He is currently the Chairman of the IEEE, Hong Kong Section, Computer Chapter. His research interests include real-time data management, mobile computing, and transaction processing. Xiao Wu received the B.Eng. and M.S. degrees in computer science from Yunnan University, Kunming, China, in 1999 and 2002, respectively. He is currently a Ph.D. candidate in the Department of Computer Science at the City University of Hong Kong. He was with the Institute of Software, Chinese Academy of Sciences, Beijing, China, between January 2001 and July 2002. From 2003 to 2004, he was with the Department of Computer Science of the City University of Hong Kong, Hong Kong, as a Research Assistant. His research interests include multimedia information retrieval, video computing and mobile computing. Joseph Kee-Yin NG received a B.Sc. in Mathematics and Computer Science, a M.Sc. in Computer Science, and a Ph.D. in Computer Science from the University of Illinois at Urbana-Champaign in the years 1986, 1988, and 1993, respectively. Prof. Ng is currently a professor in the Department of Computer Science at Hong Kong Baptist University. His current research interests include Real-Time Networks, Multimedia Communications, Ubiquitous/Pervasive Computing, Mobile and Location- aware Computing, Performance Evaluation, Parallel and Distributed Computing. Prof. Ng is the Technical Program Chair for TENCON 2006, General Co-Chair for The 11th International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA 2005), Program Vice Chair for The 11th International Conference on Parallel and Distributed Systems (ICPADS 2005), Program Area-Chair for The 18th & 19th International Conference on Advanced Information Networking and Applications (AINA 2004 & AINA 2005), General Co-Chair for The International Computer Congress 1999 & 2001 (ICC’99 & ICC’01), Program Co-Chair for The Sixth International Conference on Real-Time Computing Systems and Applications (RTCSA’99) and General Co-Chair for The 1999 and 2001 International Computer Science Conference (ICSC’99 & ICSC’01). Prof. Ng is a member of the Editorial Board of Journal of Pervasive Computing and Communications, Journal of Ubiquitous Computing and Intelligence, Journal of Embedded Computing, and Journal of Microprocessors and Microsystems. He is the Associate Editor of Real-Time Systems Journal and Journal of Mobile Multimedia. He is also a guest editor of International Journal of Wireless and Mobile Computing for a special issue on Applications, Services, and Infrastructures for Wireless and Mobile Computing. Prof. Ng is currently the Region 10 Coordinator for the Chapter Activities Board of the IEEE Computer Society, and is the Coordinator of the IEEE Computer Society Distinguished Visitors Program (Asia/Pacific). He is a senior member of the IEEE and has been a member of the IEEE Computer Society since 1991. Prof. Ng has been an Exco-member (1993–95), General Secretary (1995–1997), Vice-Chair (1997–1999), Chair (1999–2001) and the Past Chair of the IEEE, Hong Kong Section, Computer Chapter. Prof. Ng received the Certificate of Appreciation for Services and Contribution (2004) from IEEE Hong Kong Section, the Certificate of Appreciation for Leadership and Service (2000–2001) from IEEE Region 10 and the IEEE Meritorious Service Award from IEEE Computer Society at 2004. He is also a member of the IEEE Communication Society, ACM and the Founding Member for the Internet Society (ISOC)-Hong Kong Chapter.     

Quantum Bit-commitment for small storage based on quantum one-way permutations

We propose a quantum bit-commitment scheme based on quantum one-way permutations with the unconditionally binding and computationally concealing property. Our scheme reduces exponentially the number of bits which the receiver needs to store until, the opening phase compared with the classical counterpart. Keisuke Tanaka, Ph.D.: He is Assistant Professor of Department of Mathematical and Computing Sciences at Tokyo Institute of Technology. He received his B.S. from Yamanashi University in 1992 and his M.S. and Ph.D. from Japan Advanced Institute of Science and Technology in 1994 and 1997, respectively. For each degree, he majored in computer science. Before joining Tokyo Institute of Technology, he was Research Engineer at NTT Information Sharing Platform Laboratories. His research interests are cryptography, quantum computation, circuit complexity, and the design and analysis of algorithms.