E-LETTER on Systems, Control, and Signal Processing ISSUE No. 57, 30 Dec 1992 Editors: Bradley W. Dickinson bradley@princeton.edu or bradley@pucc.bitnet Eduardo D. Sontag sontag@hilbert.rutgers.edu or sontag@pisces.bitnet Welcome. We remind you that items for posting can be emailed to either of the editors. PLEASE SEND CONTRIBUTIONS, since the eletter can only be useful if everyone participates. A REQUEST: It would be useful if articles are already sent in the format that we use, starting with a "Contributed by:..." and a title centered in the next line. In addition, please provide a 60-character title for the Contents. Thanks! NOTE: if you are using an editor to read this mailing and if at any point you wish to skip to the next article, you can accomplish this by searching for the string: *.** Contents New Books Published: An Introduction to Intelligent and Autonomous Control, P.J. Antsaklis and K.M. Passino, Eds. Synchronization and Linearity: An Algebra for Discrete Event Systems, F. Baccelli, G. Cohen, G.J. Olsder, and J.-P. Quadrat Large Deviations Techniques and Applications, A. Dembo and O. Zeitouni Positions Available/Wanted: Post-Doc Fellowships for European Research Network System Identification Post-Doc position, Simon Fraser Univ. Asst. Prof. in Appl. Math, Univ. of Texas, Dallas Asst. Prof. in Appl. Math, Univ. of Toledo Research Associate, NEC Research Institute Post-Doc Fellowships at Institute for Systems Research, Univ. of Maryland Faculty Position, ESE Dept., Univ. of Connecticut Positions with Speech Recognition Group, IBM Research UPATE ON SCAD DATABASE Misc: Johns Hopkins ECE Reports, ftp archive Recent Ph.D. Dissertation SIAM membership list available Internet News Group for control (sci.engr.control) Control Lab equipment query Out-of-print book (Csiszar-Korner) wanted LaTeX overlays for postscript figures *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by Kevin Passino NEW BOOK ANNOUNCEMENT: AN INTRODUCTION TO INTELLIGENT AND AUTONOMOUS CONTROL PANOS J. ANTSAKLIS AND KEVIN M. PASSINO, EDS. KLUWER ACADEMIC PUBLISHERS, NORWELL MA, 1993. ------------------------------ Back cover of the book: The area of Intelligent Control is a fusion of a number of research areas in engineering, computer science, and mathematics which has evolved from conventional control to enhance the existing nonlinear, optimal, adaptive, and stochastic control methods. Intelligent control techniques are currently being utilized for closed-loop feedback control in space-based applications, manufacturing systems, robotic systems, avionic systems, among others, to enhance system performance, reliability, and efficiency. Overall, the primary objective of intelligent control is to enhance the performance of the system to the extent that it achieves some level of autonomous operation. An Introduction to Intelligent and Autonomous Control provides an introduction to, and survey of the vital and emerging area of intelligent control by leading researchers in the area. The fundamental theory, architectures, and perspectives on intelligent control are presented. Approaches to intelligent control, including expert control, planning systems, fuzzy control, neural control, and learning control are studied in detail. Applications are introduced via robotic systems, avionic systems, and failure diagnosis for process operations. An Introduction to Intelligent and Autonomous Control is a reference for professionals and academic researchers and may be used as the foundation for graduate level courses on Intelligent and Autonomous Control. ---------------------- Table of Contents: Preface: George N. Saridis Overview: Panos J. Antsaklis and Kevin M. Passino Part I: Theory and Architectures Chapter 1: Introduction to Intelligent Control Systems with High Degrees of Autonomy Panos J. Antsaklis and Kevin M. Passino Chapter 2: A Reference Model Architecture for Intelligent Systems Design James S. Albus Chapter 3: Model-Based Architecture Concepts for Autonomous Systems Design and Simulation Bernard P. Zeigler and Sungdo Chi Chapter 4: Design of Structure-Based Hierarchies for Distributed Intelligent Control Levent Acar and Umit Ozguner Chapter 5: Modeling and Design of Distributed Intelligence Systems Alexander H. Levis Chapter 6: Nested Hierarchical Control Alex Meystel Part II: Design Approaches and Techniques Chapter 7: Expert Control Karl J. Astrom and Karl-Erik Arzen Chapter 8: Modeling and Analysis of Artificially Intelligent Planning Systems Kevin M. Passino and Panos J. Antsaklis Chapter 9: Fuzzy and Neural Control Hamid R. Berenji Chapter 10: Learning Control Systems Jay A. Farrell and Walter Baker Chapter 11: Learning Control: Methods, Needs and Architectures Mieczyslaw M. Kokar Chapter 12: Learning in Control Edward Grant Part III: Applications Chapter 13: Intelligent Robot Prehension Thang N. Nguyen and Harry Stephanou Chapter 14: Modeling of Multi Sensory Robotic Systems with Failure Diagnostic Capabilities Kimon P. Valavanis and Guna Seetharaman Chapter 15: AUTOCREW: A Paradigm for Intelligent Flight Control Brenda L. Belkin and Robert F. Stengel Chapter 16: A Framework for Knowledge-Based Diagnosis in Process Operations P.R. Prasad and James F. Davis Index ----------------------------- Information on ordering: Kluwer Academic Publishers 101 Philip Drive Assinippi Park Norwell, MA 02061 phone: 617-871-6600 email: kluwer@world.std.com ISBN: 0-7923-9267-1, Hardcover, 430 pages *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: Geert Jan Olsder (WST) ANNOUNCEMENT OF NEW BOOK ON DISCRETE EVENT SYSTEMS Title: Synchronization and Linearity: An Algebra for Discrete Event Systems authors: F. Baccelli (INRIA, Sophia Antipolis, France) G. Cohen (Ecole des Mines de Paris, Fontainebleau, France) G.J. Olsder (Delft University of Technology, the Netherlands) J.-P. Quadrat (INRIA, Rocquencourt, France) publisher: John Wiley (England office) ISBN 0 471 93609 X year of publication: 1992 number of pages xix+489 price 39.95 English Pounds This book proposes a unified mathematical treatment of a class of "linear" discrete event systems, which contains important subclasses of Petri nets and queuing networks with synchronization constraints. The linearity has to be understood with respect to nonstandard algebraic structures, e.g. the "max-plus algebra". A calculus is developed based on such structures, which is followed by tools for computing the time behaviour of such systems. This algebraic vision lays the foundation of a bona fide "discrete event system theory", which is shown to parallel the classical linear system theory in several ways. This class of synchronized systems finds its main current industrial applications in the modeling, optimization and control of communication networks, computer architectures, manufacturing and transportation systems. The book should hence appeal to students and researchers in probability-statistics, applied mathematics, (industrial and electrical) engineering, operations research as well as computer and management scientists. The book consists of four parts, containing nine chapters. The contents are: Preface part i Discrete Event Systems and Petri Nets chapter 1 Introduction and Motivation 1.1 Preliminary Remarks and Some Notation 1.2 Miscellaneous Examples 1.3 Issues and Problems in Performance Evaluation 1.4 Notes chapter 2 Graph Theory and Petri Nets 2.1 Introduction 2.2 Directed Graphs 2.3 Graphs and Matrices 2.4 Petri Nets 2.5 Timed Event Graphs 2.6 Modeling Issues 2.7 Notes part ii Algebra chapter 3 Max-Plus Algebra 3.1 Introduction 3.2 Matrices in Rmax 3.3 Scalar Functions in Rmax 3.4 Symmetrization of the Max-Plus Algebra 3.5 Linear Systems in S 3.6 Polynomials with Coefficients in S 3.7 Asymptotic Behavior of A^k 3.8 Notes chapter 4 Dioids 4.1 Introduction 4.2 Basic Definitions and Examples 4.3 Lattice Properties of Dioids 4.4 Isotone Mappings and Residuation 4.5 Fixed-Point Equations, Closure of Mappings and Best Approximation 4.6 Matrix Dioids 4.7 Dioids of Polynomials and Power Series 4.8 Rational Closure and Rational Representations 4.9 Notes part iii Deterministic System Theory chapter 5 Two-Dimensional Domain Description of Event Graphs 5.1 Introduction 5.2 A Comparison Between Counter and Dater Descriptions 5.3 Daters and their Embedding in Nonmonotonic Functions 5.4 Moving to the Two-Dimensional Description 5.5 Counters 5.6 Backward Equations 5.7 Rationality, Realizability and Periodicity 5.8 Frequency Response of Event Graphs 5.9 Notes chapter 6 Max-Plus Linear System Theory 6.1 Introduction 6.2 System Algebra 6.3 Impulse Responses of Linear Systems 6.4 Transfer Functions 6.5 Rational Systems 6.6 Correlations and Feedback Stabilization 6.7 Notes part iv Stochastic Systems chapter 7 Ergodic Theory of Event Graphs 7.1 Introduction 7.2 A Simple Example in Rmax 7.3 First-Order Theorems 7.4 Second-Order Theorems; Nonautonomous Case 7.5 Second-Order Theorems; Autonomous Case 7.6 Stationary Marking of Stochastic Event Graphs 7.7 Appendix on Ergodic Theorems 7.8 Notes chapter 8 Computational Issues in Stochastic Event Graphs 8.1 Introduction 8.2 Monotonicity Properties 8.3 Event Graphs and Branching Processes 8.4 Markovian Analysis 8.5 Appendix 8.6 Notes part v Postface chapter 9 Related Topics and Open Ends 9.1 Introduction 9.2 About Realization Theory 9.3 Control of Discrete Event Systems 9.4 Brownian and Diffusion Decision Processes 9.5 Evolution Equations of General Timed Petri Nets 9.6 Min-Max Systems 9.7 About Cycle Times in General Petri Nets 9.8 Notes Bibliography Notation Index *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: zeitouni@lids.mit.edu (Ofer Zeitouni) BOOK ANNOUNCEMENT LARGE DEVIATIONS TECHNIQUES AND APPLICATIONS Amir Dembo and Ofer Zeitouni ISBN 0-86720-291-2 346 pp., $34.50 December 1992 Jones and Bartlett Publishers, INC. One Exeter Plaza Boston, MA 02116 Phone: 617- 859-8198 FAX: 617-859-7675 Internet: kpeters@geom.umn.edu >From the preface: In recent years, there has been renewed interest in the (old) topic of large deviations, namely, the asymptotic computation of small probabilities on an exponential scale. The reasons for this interest are twofold. On the one hand, starting with Donsker and Varadhan, a general foundation was laid which allowed one to point out several ``general'' tricks which seem to work in diverse situations. On the other hand, large deviations estimates have proved to be the crucial tool required to handle many questions in statistics, engineering, statistical mechanics and applied probability. The field of large deviations is now mature enough to enable one to expose the basic ideas and representative applications in a systematic way. Indeed, such treatises exist: see, e.g., the books of Ellis and Deuschel--Stroock. However, in view of the diversity of the applications, there is a wide diversity in the background of those who need to apply the theory. This book is an attempt to provide a rigorous exposition of the theory, which is geared towards such different audiences. We believe that in a field as technical as ours, a rigorous presentation is called for. Running the risk of satisfying nobody, we tried to expose large deviations in such a way that the principles are first discussed in a relatively simple, finite dimensional setting, and the abstractization which follows is motivated and based on it and on real applications which make use of the ``simple'' estimates. This is also the reason for our putting our emphasis on the projective limit approach, which is the natural tool to pass from simple finite dimensional statements to abstract ones. The mathematical sophistication required from the reader runs from a senior undergraduate level in mathematics/statistics/engineering (for Chapters 2,3) to advanced graduate level for the latter parts of the book. Table of Contents Preface 1 Introduction 1.1 Rare Events and Large Deviations 1.2 The Large Deviation Principle (LDP) 1.3 Historical Notes and References 2 LDP for Finite Dimensional Spaces 2.1 Combinatorial Techniques for Finite Alphabets 2.1.1 The Method of Types and Sanov's Theorem 2.1.2 Cramer's Theorem for Finite Alphabets in R 2.1.3 Large Deviations for Sampling without Replacement 2.2 Cramer's Theorem 2.2.1 Cramer's Theorem in R 2.2.2 Cramer's Theorem in R^d 2.3 The Gartner--Ellis Theorem 2.4 Historical Notes and References 3 Applications---The Finite Dimensional Case 3.1 Large Deviations for Finite State Markov Chains 3.1.1 LDP for Additive Functionals of Markov Chains 3.1.2 Sanov's Theorem for the Empirical Measure of Markov Chains 3.1.3 Sanov's Theorem for the Pair Empirical Measure of Markov Chains 3.2 Long Rare Segments in Random Walks 3.3 The Gibbs Conditioning Principle for Finite Alphabets 3.4 The Hypothesis Testing Problem 3.5 Generalized Likelihood Ratio Test for Finite Alphabets 3.6 Rate Distortion Theory 3.7 Refinements of Large Deviations in R^d 3.8 Historical Notes and References 4 General Principles 4.1 Existence of an LDP and Related Properties 4.1.1 Properties of the LDP 4.1.2 The Existence of an LDP 4.2 Transformations of LDPs 4.2.1 Contraction Principles 4.2.2 Exponential Approximations 4.3 Varadhan's Integral Lemma 4.4 Bryc's Inverse Varadhan Lemma 4.5 LDP in Topological Vector Spaces 4.5.1 A General Upper Bound 4.5.2 Convexity Considerations 4.5.3 Abstract Gartner--Ellis Theorem 4.6 Large Deviations for Projective Limits 4.7 Historical Notes and References 5 Sample Path Large Deviations 5.1 Sample Path Large Deviations for Random Walks 5.2 Brownian Motion Sample Path Large Deviations 5.3 Multivariate Random Walk and Brownian Sheet 5.4 Performance Analysis of DMPSK Modulation 5.5 Large Exceedances in R^d 5.6 The Freidlin--Wentzell Theory 5.7 The Problem of Diffusion Exit from a Domain 5.8 The Performance of Tracking Loops 5.8.1 An Angular Tracking Loop Analysis 5.8.2 The Analysis of Range Tracking Loops 5.9 Historical Notes and References 6 The LDP for Abstract Empirical Measures 6.1 Cramer's Theorem in Polish Spaces 6.2 Sanov's Theorem 6.3 LDP for the Empirical Measure---the Uniform Markov Case 6.4 Mixing Conditions and LDP 6.4.1 LDP for the Empirical Mean in R^d 6.4.2 Empirical Measure LDP for Mixing Processes 6.5 LDP for Empirical Measures of Markov Chains 6.5.1 LDP for Occupation Times 6.5.2 LDP for the k-Empirical Measures 6.5.3 Process Level LDP for Markov Chains 6.6 Historical Notes and References 7 Applications of Empirical Measures LDP 7.1 Universal Hypothesis Testing 7.1.1 A General Statement of Test Optimality 7.1.2 Independent and Identically Distributed Observations 7.2 Sampling without Replacement 7.3 The Gibbs Conditioning Principle 7.3.1 The Non-Interacting Case 7.3.2 The Interacting Case 7.4 Historical Notes and References Appendix A Convex Analysis Considerations in R^d B Topological Preliminaries B.1 Generalities B.2 Topological Vector Spaces and Weak Topologies B.3 Banach and Polish Spaces B.4 Mazur's Theorem C Integration and Function Spaces C.1 Additive Set Functions C.2 Integration and Spaces of Functions D Probability Measures on Polish Spaces D.1 Generalities D.2 Weak Topology E Stochastic Analysis Bibliography General Conventions Glossary Index *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: Jan H. van Schuppen (schuppen@cwi.nl) CALL FOR FELLOWSHIP APPLICATIONS, issued by the EUROPEAN RESEARCH NETWORK SYSTEM IDENTIFICATION Applications are invited for post-doctoral fellowships at the research teams of the European Research Network System Identification. Please show this call to potential applicants and post it at your institute. FELLOWSHIPS The Commission of the European Communities has made funds available for the Program Human Capital and Mobility. The aim of this program is to invest in the scientists and researchers of European countries. The European Research Network System Identification has applied to this program for financial support for post-doctoral Research Training Fellowships. The Commission has recently informed the network that its application has been selected to receive financial support. The Commission regards the network as a pre-selected host institute. CALL FOR APPLICATIONS Post-doctoral researchers are invited to apply to the network for a fellowship. Applications from post-doc researchers living in the less- favoured regions of the European Community are particularly welcome. Fellowships are available that permit a stay at any of the eight research teams for a maximum stay of 6 months per team. Applications for visits to two teams will also be considered. The appointments can start on January 1, 1993 at the earliest. Fellowships are available during the years 1993 to 1995. Eligible is any national of a member state of the European Community, or of a country treated as a member state, or a resident in the European Community (see the Information Package mentioned below for the precise rules). The applicant is only allowed to visit a research team if he is a national of a country other than that in which the research team is established. HOW TO APPLY? A Call for Fellowship Applications with information on the application procedure and an Information Package for fellowship applications to selected host institutes, may be requested from the coordinator of the network, see below for the address. Applications must be submitted to the coordinator. Applications may be submitted at any moment. There will be several rounds of selections each year. For an application to be considered in the first selection round it must reach the coordinator by September 29, 1992. The closing date of the second round has not yet been determined but it is likely to be March 31, 1993. SELECTION PROCEDURE The council of project managers of the network will make a selection of the applications. For the first selection round a recommendation of the council must be received by the Commission of the European Communities before October 15, 1992 at 17:00 hours. EUROPEAN RESEARCH NETWORK SYSTEM IDENTIFICATION Several research groups in system identification have formed the research network. This network comprises eight research teams in seven European countries. A list of all teams is presented below. The aim of the network is to stimulate cooperation between the research teams in the research area of system identification. The Commission has earlier in 1992 signed a contract with the network for a project titled System Identification that is funded through the SCIENCE program. This project provides funds for joint workshops and work visits. COORDINATOR The coordinator of the network is Prof. J.H. van Schuppen. Address: CWI - Centre for Mathematics and Computer Science, P.O. Box 4079, 1009 AB Amsterdam, The Netherlands, Tel. +31-20-5924085 (office), +31-20-5924189 (secretary), +31-20-5929333 (switchboard), Fax +31-20-5924199, email schuppen@cwi.nl. RESEARCH TEAMS OF THE NETWORK Research team of the Netwerk Systeem- en Regeltheorie (Systems and Control Theory Network) of the University of Groningen, at Groningen, The Netherlands. Team leader is J.H. van Schuppen. Five research groups of the NSRT participate in this research team: - Research group of the Erasmus University in Rotterdam. Group leader is Dr. C. Heij. - Research group at Tilburg University in Tilburg. Group leader is Prof. J.M. Schumacher. - Research group at the Department of Mathematics and the Department of Economics of the University of Groningen. Group leader is Dr. J.W. Nieuwenhuis. - Research group of the Free University in Amsterdam. Group leader is Dr. B. Hanzon. - Research group at the Centre for Mathematics and Computer Science (CWI) in Amsterdam. Group leader is Prof. J.H. van Schuppen. Research team of the Institut fuer Okonometrie, Operations Research und Systemtheorie; Abteilung fuer Okonometrie und Systemtheorie, Technische Universitaet Wien in Vienna, Austria. Team leader is Prof. M. Deistler. Research team of the Laboratoire d'Automatique, Dynamique et Analyse des Systemes, Universite Catholique de Louvain in Louvain-la-Neuve. Team leader is Prof. M. Gevers. Research team of the Institut National de Recherche en Informatique et Automatique (INRIA), Unite de Recherche Sophia Antipolis, Sophia Antipolis, France. Team leader is Prof. L. Baratchart. Research team of the Institut de Recherche en Informatique et Systemes Aleatoires (IRISA), Universite de Rennes, France. Team leader is Prof. J.-J. Fuchs. Research team of the Department of Engineering, University of Cambridge, Great Britain. Team leader is Prof. J.M. Maciejowski. Research team of the Istituto per Ricerche di Dinamica dei Sistemi e di Bioingegneria (LADSEB), of the Consiglio Nazionale delle Ricerche (CNR) in Padova, Italy. Team leader is Prof. G. Picci. Research team of the Institutionen fuer Systemteknik, University of Linkoping, Linkoping, Sweden. Team leader is Prof. L. Ljung. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: M. Saif, saif@cs.sfu.ca Post Doctoral Position We are looking for a post doctoral researcher in the general area of automatic control. We are particularly interested in someone with research experience in the areas such as robust estimation and control, fault tolerant and reconfigurable control system design. This is a one year appointment and it could be renewed subject to the availability of funding. The position is in the School of Engineering Science at Simon Fraser University. SFU is located in Burnaby, a suburb of Vancouver. Interested candidates should forward a c.v. along with the names and addresses of at least three referees to Dr. M. Saif School of Engineering Science Simon Fraser University Burnaby, B.C. V5A 1S6 CANADA *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** contributed by: L.R. Hunt (hunt@utdallas.edu) The University of Texas at Dallas Programs in Mathematical Sciences Applications are invited for an anticipated tenure track assistant professor faculty position in Applied Mathematics beginning Fall, 1993. Ph.D. in relevant field is required. The successful candidate is expected to participate in the activities of the Center for Engineering Mathematics. Candidates with both a strong theoretical background and a strong interest in applications are particularly encouraged to apply. Areas of special interests are mathematical modeling, system theory, signal processing, and numerical analysis. Responsibilities include research, teaching and supervision of Ph.D. dissertations. Excellent computing facilities. Applicants should send a curriculum vitae and at least three letters of reference (indications of sex and ethnicity for affirmative action statistical purposes is requested but not required) to: Academic Search #2006, M/S AD23, The University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083-0688. Applications accepted until 12/15/92, or later if position is not filled. The University of Texas at Dallas is an Affirmative Action/Equal Opportunity Employer. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: Dean A. Carlson (dcarlso@uoft02.utoledo.edu) FACULTY POSITION IN APPLIED MATHEMATICS INSTITUTION: University of Toledo DEPARTMENT: Mathematics CONTACT PERSON: Harvey Wolff E-MAIL ADDRESS: fac3330@uoft01.utoledo.edu DESCRIPTION: The department invites applications for a tenure- track position in applied mathematics at the rank of assistant professor, to begin in September 1993. Requirements include a Ph.D. (or commitment to excellence in both teaching and research). Applicants should send curriculum vitae and arrange for 3 letters of reference to be sent to: Harvey Wolff, Chair, Department of Mathematics, University of Toledo, Toledo, OH 43606-3390. The University of Toledo is an equal opportunity/ affirmative action employer. Applications from women and minorities are especially welcome. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by giles@research.nj.nec.com (Lee Giles) POSITION: RESEARCH ASSOCIATE The NEC Research Institute in Princeton, NJ has an immediate opening for a RESEARCH ASSOCIATE in the area of neural networks/connectionism and dynamics/control. Research is currently underway to better understand dynamic neural networks and their computational capabilities. Towards this end, we are looking for a research associate who will contribute to this research effort and work closely with the research group. The successful candidate must have experience in basic research and be able to effectively communicate research results. He or she should have experience in using computer simulations, preferably in the area of artificial neural networks. In addition his or her background should include extensive experience in programming in the UNIX/C environment (nearly all work is performed on Silicon Graphics workstations). Tasks in this area will also involve code maintenance, modification and enhancement as required by the research program. Interested applicants should send their resumes by mail, fax or email with 2 references to: Dr. C. Lee Giles NEC Research Institute 4 Independence Way Princeton, NJ 08540 Phone: 609-951-2642 FAX: 609-951-2482 email:giles@research.nj.nec.com Applicants must show DOCUMENTATION OF ELIGIBILITY FOR EMPLOYMENT. NEC is an equal opportunity employer: M/F/H/V. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by sue@src.umd.edu (Susan Frazier) The Institute for Systems Research (formerly Systems Research Center) is soliciting Post-Doctoral Fellowship applicants. PDOC Fellowships are intended for Ph.D. recipients in: Engineering, Computer Science, Mathematics, and Related Areas Departments participating in the research of the Institute for Systems Research (ISR) include: % Aerospace Engineering % Business & Management % Chemical Engineering % Civil Engineering % Computer Science % Electrical Engineering % Materials and Nuclear Engineering % Mathematics % Mechanical Engineering The Institute for Systems Research is an interdisciplinary research unit of the University of Maryland and Harvard University. It adheres to the central theme of conducting advanced interdisciplinary research in the analysis and design of high performance complex automation and information systems. The following thrust areas are emphasized: % Chemical Process Systems % Communication and Signal Processing Systems % Intelligent Servomechanisms % Manufacturing Systems % Systems Integration The Institute's research programs are at the forefront of advances in modern systems engineering, and they incorporate sophisticated analytical and computational methods with progressive experimental and modeling techniques. A multi-disciplinary team of outstanding scientists and engineers is pursuing in-depth studies in the implications and applications of modern computer technology to control and communication systems technologies. Extensive industrial collaboration is an integral part of the program. Projects encompass a diverse set of systems problems, including the design of dextrous robotic manipulators with vision, tactile and force sensors; the operations management of chemical plants; the realization of sophisticated signal processing and understanding algorithms on micro-electronic chips; the design, management and performance evaluation of communication networks; the modeling and design of advanced aircraft and spacecraft; the management and the information integration of the flexibly-automated factories of the future. Fellowships: ISR Post-Doctoral Fellowships are available for recipients of Ph.D. degrees who have interests in systems engineering and its applications. Candidates must have received their degrees by August 31 of the same year that the fellowship begins. Typically, fellowships are effective from September through August. Academic excellence and outstanding potential for basic research weigh heavily in fellowship selection. Benefits: ISR Post-Doctoral Fellows enjoy the unique opportunity of participating in state-of-the-art research in systems engineering. Exceptional opportunities exist for research in collaboration with leading industrial and government research laboratories. ISR Post-Doctoral Fellow appointments offer generous stipends ($40K approximately) and provide excellent benefits. Post- doctoral appointments are typically for one year and are renewable up to a second year based on performance and the availability of funds. Application: To be considered for a post-doctoral appointment, applicants must submit the following materials: % curriculum vitae including a list of publications, % statement of research interests and goals, including the reason one wishes to participate in this program, % sample publications, % three letters of recommendation, % a transcript from the institution where the Ph.D. was (or will be) earned (showing grades in courses taken). All materials must be received by the Institute for Systems Research by January 15th to qualify candidates for fall consideration. Institute for Systems Research A.V. Williams Building (115) University of Maryland College Park, MD 20742 ATTN: Post-Doctoral Fellowship Review Committee For additional information, call (301) 405-6599. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: willett@brc.uconn.edu (Peter Willett) POSITION AVAILABLE AT THE UNIVERSITY OF CONNECTICUT Applications are invited for a tenure track faculty position at the Assistant or Associate Professor level. Necessary qualifications include an earned doctorate, a strong commitment to effective undergraduate and graduate teaching, and outstanding scholarly research achievement and/or potential. Technical areas of interest include communications, communication networks, and digital signal/image processing. Send application letter to: Dr. Peter K. Cheo Chairman, ESE Department University of Connecticut 260 Glenbrook Road Storrs, CT 06269-3157 The review of applications will begin on January 4, 1993, and will continue until the position is filled. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by Fred Jelinek The Continuous Speech Recognition group of the IBM Thomas J. Watson Research Center has several openings for recent graduates. These concern both permanent and term employment. We carry out research on dictation transcription and over-the-telephone dialogue. We are attacking problems of speaker independence and adaptation, noise robustness, predictive language modeling, grammar extraction, text understanding, man/machine interaction, etc. We are looking for the brightest available people regardless of previous specialization. The only conditions are capability and willingness to program and familiarity and sympathy with a statistical (probabilistic) formulation of problems. Interested candidates should contact me either by phone, electronic mail or regular post. Frederick Jelinek Senior Manager Continuous Speech Recognition IBM Thomas J. Watson Research Center P. O. Box 704 Yorktown Heights, NY 10598 Phone Number: (914) 784-6519 E-MAIL: jelinek@watson.ibm.com *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by Raimund J. Ober UPDATE ON SCAD DATABASE -- #### #### ## ##### # # # # # # # #### # # # # # # # ###### # # # # # # # # # # #### #### # # ##### Systems and Control Archive at Dallas ftp address: ftp.utdallas.edu IP number: (129.110.10.11) IMPORTANT: for technical reasons the IP number for the next few weeks is: 129.110.10.1 queries: ober@utdallas.edu ****************************************************************************** New contents: ============= The following scad directories contain new material: NEW!!!!!! ========= There is a new subdirectory (cacsdletters/digest) that contains archive versions of the Usenet newsgroup sci.engr.control. (Note: a news item about this newsgroup appears later in the E-Letter) There is also a new subdirectory (nonlineartoolbox/bugs) that contains information about bugs of the nonlinear toolbox. cacsdletters: ============= subdirectory `letters' - Open CACSD vol 1 number 8: cacsdv1n8 subdirectory `digest' - News digest: digestv1n1, digestv1n2, digestv1n3, digestv1n4, digestv1n5, digestv1n7 nonlinear toolbox: ================== bugs: a new subdirectory has been introduced that contains information about bugs that were found in the toolbox contains: bug1 (concerns problems with showsys etc.) eletters: ========= - eletter issues: 53-1, 53-2, 54, 55 preprints: ========== - J. Rosenthal: On Dynamic Feedback Compensation and Compactification of Systems rosenthal.poledymanic.latex Necessary and sufficient conditions are given when a strictly proper or proper system can be generically pole assigned by a complex dynamic compensator with a bounded McMillan degree. the file is a latex file - J. Sefton and R. Ober, On the gap metric and coprime factor perturbations seftongap.dvi.Z The preprint contains new results on various aspects of robust control from the point of view of gap metric and coprime factor uncertainty models. the file is a compressed dvi file - syconreports: sycon-92-05.ps.Z (compressed postscript file) "Neural networks with real weights: analog computational complexity: by Hava T. Siegelmann and Eduardo D. Sontag, September 1992. (24 + i pp) We pursue a particular approach to analog computation, based on dynamical systems of the type used in neural networks research. Our systems have a fixed structure, invariant in time, corresponding to an unchanging number of ``neurons''. If allowed exponential time for computation, they turn out to have unbounded power. However, under polynomial-time constraints there are limits on their capabilities, though being more powerful than Turing Machines. (A similar but more restricted model was shown to be polynomial-time equivalent to classical digital computation in previous work.) Moreover, there is a precise correspondence between nets and standard non-uniform circuits with equivalent resources, and as a consequence one has lower bound constraints on what they can compute. This relationship is perhaps surprising since our analog devices do not change in any manner with input size. We note that these networks are not likely to solve polynomially NP-hard problems, as the equality ``P = NP'' in our model implies the almost complete collapse of the standard polynomial hierarchy. In contrast to classical computational models, the models studied here exhibit at least some robustness with respect to noise and implementation errors. - syconreports: sycon-92-06.ps.Z (compressed postscript file) "Further results on controllability properties of discrete-time nonlinear systems," by Francesca Albertini and Eduardo D. Sontag, November 1992. (17+i) Controllability questions for discrete-time nonlinear systems are addressed in this paper. In particular, we continue the search for conditions under which the group-like notion of transitivity implies the stronger and semigroup-like property of forward accessibility. We show that this implication holds, pointwise, for states which have a weak Poisson stability property, and globally, if there exists a global ``attractor'' for the system. *********** Remember to send your tech reports and other material! ********* How to access scad: =================== Scad can be accessed using ftp. The ftp address is: ftp ftp.utdallas.edu (IP number: 129.110.10.11 (129.110.10.1 for the time being) You simply type: ftp ftp.utdallas.edu or: 129.110.10.11 (129.110.10.1 for the time being) When asked for your name, type: anonymous When asked for your password, type your emailaddress: me@mymachine.myuniversity To get to scad type: cd pub/scad To get more info about scad get the README file and examine it on your machine: get README To see the directories in scad type: dir To change to (e.g.) conferences: cd conferences To see the subdirectories: dir To change to the CDC91 subdirectory: cd 91cdc-prog To examine this directory: dir To get a file, type e.g.: get AdvPrgmFinal-Wed.txt To finish the session: quit What follows is an example of such a session: ftp ftp.utdallas.edu Connected to ASPEN.UTDALLAS.EDU. 220 aspen.utdallas.edu FTP server (Version 5.64) ready. Name (ftp.utdallas.edu:joe): anonymous 331 Guest login ok, please send your e-mail address as a password. Password: 230 Guest login ok, access restrictions apply. ftp> cd pub/scad/conferences/91cdc-prog 250 CWD command successful. ftp> get README 200 PORT command successful. 150 Opening ASCII mode data connection for README (77 bytes). 226 Transfer complete. local: README remote: README 79 bytes received in 0.04 seconds (1.9 Kbytes/s) ftp> get AdvPrgmFinal-Wed.txt 200 PORT command successful. 150 Opening ASCII mode data connection for AdvPrgmFinal-Wed.txt (44311 bytes). 226 Transfer complete. local: AdvPrgmFinal-Wed.txt remote: AdvPrgmFinal-Wed.txt 45857 bytes received in 7.3 seconds (6.1 Kbytes/s) ftp> get AdvPrgmFinal-Th.txt 200 PORT command successful. 150 Opening ASCII mode data connection for AdvPrgmFinal-Th.txt (42454 bytes). 226 Transfer complete. local: AdvPrgmFinal-Th.txt remote: AdvPrgmFinal-Th.txt 43909 bytes received in 20 seconds (2.1 Kbytes/s) ftp> get AdvPrgmFinal-F.txt 200 PORT command successful. 150 Opening ASCII mode data connection for AdvPrgmFinal-F.txt (42111 bytes). 226 Transfer complete. local: AdvPrgmFinal-F.txt remote: AdvPrgmFinal-F.txt 43571 bytes received in 7 seconds (6.1 Kbytes/s) ftp> quit MORE INFO: There is README file in /pub/scad which contains more info on how to submit material to SCAD. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: Wilson J. Rugh JOHNS HOPKINS ECE TECHNICAL REPORTS Technical reports and other documents from the Department of Electrical and Computer Engineering Department at Hopkins are now available via ftp from a guest account "ece_tr" on the machine "jhunix.hcf.jhu.edu" (IP number 128.220.2.5). Below is printed a portion of the READ.ME file in the account, which includes a sample session, and the current INDEX file in the account, which describes the currently available files. _____________________________________________________________________________ READ.ME (portion) The text file grad_brochure.text describes the graduate program in the Department. This file is suitable for printing on any printer. A postscript version of the file is grad_brochure.ps for printing on a postscript printer. Many reports listed in INDEX are provided as postscript files (e.g. 92-03.ps) or compressed postscript files (e.g. 92-04.ps.Z). Any file in the account is available via ftp. A sample session is: % %ftp jhunix.hcf.jhu.edu [128.220.2.5] Name: ece_tr 331- Please send you complete email address as your password. Password: [your email address] 230- ... Guest login message ... ftp> binary ftp> get READ.ME ftp> get INDEX ftp> get filename.ps [filename.ps.Z] ftp> quit % Remember to set ftp to `binary' to transfer compressed (.Z) files. Reports listed in the INDEX for which there are not corresponding postscript files are available in hardcopy by writing Technical Reports ECE Department Johns Hopkins University Baltimore, MD 21218 USA ____________________________________________________________________________ INDEX 92-01 Hierarchical Reconstruction Using Geometry and Sinogram Restoration, Jerry L. Prince and Alan S. Willsky (33 pages, February 1992, revised 25 September 1992) 92-02 An Approach to Gain Scheduling on Fast Variables, Di Guo and Wlson J. Rugh (14 pages, 1 March 1992, to be presented at the 1992 IEEE CDC) 92-03 Gain Scheduling for H-Infinity Controllers: A Flight Control Example, Robert T. Reichert, Robert A. Nichols, and Wilson J. Rugh (20 pages, 10 June 1992, revised 27 August 1992) 92-04 Optimal Brightness Functions for Optical Flow Estimation of Deformable Motion, Thomas S. Denney, Jr. and Jerry L. Prince (41 pages, July 1992) 92-05 Tomographic Reconstruction of 3-D Vector Fields Using Inner Product Probes, Jerry L. Prince (10 pages, July 1992) 92-06 On the Morphological Analysis of Discrete Random Shapes, John Goutsias (without figures, 45 pages, 31 July 1992, submitted to Journal of Mathematical Imaging and Vision) 92-07 An Active Contour Algorithm for Thick Curves, Chris A. Davatzikos and Jerry L. Prince (44 pages, July 1992) 92-08 Tag and Contour Detection in Tagged MR Images of the Left Ventricle, Michael A. Guttman, Jerry L. Prince, and Elliot R. McVeigh (37 pages, August 1992) 92-09 Stationarity and Reciprocity in Stochastic Multipoint Boundary Value Systems, Jie Chen and Howard L. Weinert (9 pages, August 1992, Submitted to Systems & Control Letters) 92-10 Ocean Facet Orientation Estimation from Multiparametric SAR Data, David H. Hsu and Jerry L. Prince (20 August 1992, 14 pages, submitted to IEEE Transactions on Geoscience and Remote Sensing) 92-11 Input-Output Pseudolinearization for Nonlinear Systems, Douglas A. Lawrence and Wilson J. Rugh (36 pages, 2 September 1992, Preliminary version presented at 1991 IEEE Conference on Decision and Control) 92-12 An Entropy Formula for Time-Varying Discrete-Time Systems, Pablo A. Iglesias (18 pages, 17 September 1992, Submitted to the 1993 American Control Conference) *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by Michail Tsatsanis Recent Ph.D. DISSERTATION: Title : ON WAVELETS AND TIME-VARYING SYSTEM IDENTIFICATION Author : MICHAIL K. TSATSANIS Advisor : Georgios B. Giannakis Granting Institution : University of Virginia Acceptance Date : September 1992 Further Information : Contact author c/o G. B. Giannakis Dept. of Electr. Eng., University of Virginia, Thornton Hall, Charlottesville VA 22903-2442 e-mail: mt3f@virginia.edu ABSTRACT: ON WAVELETS AND TIME VARYING SYSTEM IDENTIFICATION The main focus of this dissertation is the application of wavelet theory to the description and modeling of random signals. In the f i r s t part, the selection of optimal multiresolution representations is pursued for general classes of stationary and non-stationary processes. By integrating ideas from principal component analysis, optimal perfect reconstruction filter banks are derived which minimize the mean square error between the signal and its low-resolution component. These results are also extended to multichannel and continuous time signals. Apart from the more immediate application to signal coding, optimal multi- resolution representations are adopted for modeling time-varying (TV) systems in the s e c o n d part of the dissertation. The TV system parameters are expanded onto a wavelet basis and the time invariant coefficients of the expansion are estimated. By using model order sele- ction ideas, information theoretic approaches as well as hypothesis testing procedures are developed to retain only the resolution depths which significantly contribute to the system's time evolution. The proposed algorithm determines the model's order and automatically selects the best wavelet representation of the TV parameters, by ``zooming'' into the details only when necessary. In the t h i r d part of the dissertation, multiresolution approaches and higher-order statistics are used to address the problem of blind TV channel identifi- cation. Linear and nonlinear methods are proposed, which minimize a moment matching criterion. Identifiability of the TV system is established and consistency of the estimator is shown. Finally, the potential application of these results to the blind equalization of rapidly fading, digital mobile radio channels, and to speech modeling is delineated. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Reprinted from another bboard: Eric Grosse Encrypted SIAM Membership List Available The SIAM membership list, a useful source of up-to-date addresses and phone numbers, has long been searchable via netlib. Now you can also download it to your own machine for faster searching. To preserve privacy, i.e. to keep the list from being used by mass mailers and telemarketers, the database is encrypted. Given a person's last name or phone number, you can decrypt that one database entry. But there is no feasible way to crack the entire list. To learn how we do this, read J. Feigenbaum, E. Grosse and J. Reeds (1992) "Cryptographic Protection of Membership Lists", Newsletter of the International Association for Cryptologic Research, 9:1,16-20. (This paper is available from netlib by "send 91-12 from research/nam".) You can use the system without understanding the mechanism. First, get the decryption program and (1.2 megabyte) database by ftp research.att.com login: netlib password: binary cd research get decryptdb.c get siamdb quit then follow the instructions at the start of decryptdb.c to install. For now, you must have ftp access and a C compiler; if demand warrants, SIAM headquarters may make the system available on other media at a later time. The database, which is updated quarterly, will continue to be searchable via netlib's "whois" command. But fast local access allows new uses; for example, my computer is connected to my phone and, when caller-ID is functioning, automatically translates the calling number into a name. ADDED: Last week's announcement of the encrypted SIAM membership list mentioned a technical report available from netlib as research/nam/91-12. As one kind reader points out, files in the "research" directory, which are from the Computing Research group at Bell Labs, are only available from the netlib@research.att.com server. Similarly, Tennessee technical reports are only archived at netlib@ornl.gov. This might also be an opportune time to remind folks that mail netlib@research.att.com send ftp from na-digest will get you some general notes on ftp'ing files, and send ftpd from na-digest will get you some notes on how to set up anonymous ftp distribution of your own technical reports, datasets, and the like. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by: Chris Jobling NEW INTERNET NEWS GROUP FOR CONTROL ENGINEERS A NEW INTERNET News Group has been created for the explicit purpose of providing an electronic forum for the discussion of topics related to control engineering. The group is called sci.engr.control and those readers familiar with Internet News (USENET) can subscribe to it straight away. Those who do not use news now but have it available at their site, may wish to look into making use of it. For others, other possibilities such as creating an electronic e-mail discussion list to pass on news and the archiving of news articles are being explored. I attach the Charter of the News Group (which was the basis on which sci.engr.control was created on a vote of 390 for and 12 against). You see that it's quite broad, although biased to the application of computers/information technology to control engineering. Please use the group for discussion of burning issues, requests for help, conference announcements, and anything else which you feel may be of interest to the control engineering community. The medium is somewhat less formal than traditional news letters, and the feedback somewhat more immediate. Enjoy! ------------------The Charter------------------------------------ NEWS GROUP NAME: sci.engr.control STATUS: unmoderated CHARTER: This forum aims to encourage discussion and free exchange of ideas amongst practicing control engineers, researchers and students on any subject related to the practice or theory of control systems and control engineering. The group aims to cover any subject related to control engineering including theory, research, and practice but particularly the use and future development of computer-based applications for the analysis, design, simulation and implementation of control systems. Examples of suitable topics would be o data definitions for control systems design packages o user interfaces for control systems design packages o system modelling languages o simulation packages o environments for the integration of CAD tools for control o the application of new computer science techniques in control systems design and implementation o commercial control systems design and analysis packages o new theories o applications of control (e.g. process industries, aerospace, transport, manufacturing, ...) o real-time software o social and environmental impact of control systems o non-engineering applications (e.g. economics, social, ...) o control systems education * One aim is to stimulate the exchange of ideas about what software systems should be devloped to support the analysis, design and implementation of control systems with a longer term-aim of the development of guidelines or examples of good practice that will eventually bring freedom to users and developers of computer-based tools. * Another aim is to provide timely notice of new academic ideas and control methods and to encourage the take-up of advanced control by industry. * A further implicit aim is to try to break down the communication barriers that traditionally exist in the control community and to introduce them to the joys of the Internet, thereby widening their horizons and opening their eyes to the benefits of the free exchange of ideas that other users of computers have known for some time. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by F.L. Lewis, Automation and Robotics Research Institute The University of Texas at Arlington email flewis@arrirs03.uta.edu CONTROLS LABORATORY EXPERIMENTS: We have investigated purchasing lab experiments for a controls research lab including: 1. inverted pendulum (single and double link) 2. coupled hydraulic tanks 3. coupled motors with compliant fanbelt 4. ball balancer 5. helicopter demo and discovered that companies that sell them commercially charge in excess of $2000. Therefore, most institutions end up having students build these devices in some lab project course. These devices are essential in today's modern lab to demonstrate principles of controls design, fb linearization, etc. We are thinking of building some of these devices and making them available to the controls community at $500-$1000 apiece. Would anyone be interested in this? If so, we will proceed with the designs and prototyping. Optional modules will be available for interface with LabView using a digital signal processor (DSP) chip. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by Brinton Cooper The seminal book, INFORMATION THEORY: CODING THEOREMS FOR DISCRETE MEMORYLESS SYSTEMS, by Imre Csiszar and Janos Korner, Academic Press, 1981, is out of print. Academic Press says that they have not sold rights for republication to Dover or anyone else. I would like to purchase a copy of this book in good condition. Please contact me if you have one to sell or know where I can get one. Brinton Cooper US Army Research Laboratory 410-278-6883 *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** Contributed by Craig Barratt Subject: Overlaying postscript figures with LaTeX fragments A new version (1.1) of the PsFrag macros is now available. This version handles a wider class of postscript figures, allowing PsFrag to work with packages such as freehand and mathematica. The PsFrag macros make it easy to overlay postscript figures with fragments of LaTeX. These macros allow you to get the best of both worlds: you can generate a postscript figure as usual using your favorite drawing or plotting program (for example, xfig, idraw, freehand, matlab, xmath, or mathematica), but each piece of text can be selectively replaced with high-quality LaTeX formatted equations, text, or pictures, when it is included in a LaTeX document. The LaTeX fragments can be optionally rotated, scaled, and repositioned relative to the text being replaced. The LaTeX fragments automatically track the postscript text position as the postscript file is updated, or as the scaling and offsets of the enclosing \special or \epsfbox are changed. PsFrag is available via anonymous ftp from isl.stanford.edu (internet address 36.60.0.10). Get the compressed tar file pub/boyd/psfrag/psfrag.tar.Z Extract the archive using uncompress and tar xvf (or gtar zxvf). See the files README, USAGE, INSTALL for detailed information. If you can't ftp then I can email you a uuencoded version. Note: PsFrag uses ghostscript (gs) from the gnu distribution, and assumes that your dvi to ps driver is Tomas Rokicki's dvips (Radical Eye Software). You will need both of these programs to use PsFrag. Basically, PsFrag uses ghostscript to interpret the postscript figure and spit out a LaTeX picture environment that exactly lines up with the postscript figure. *.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.** End of E-Letter 57, December 1992.