61 , on Massachusetts Institute of Technology Laboratory for Computer Science July 1985- Progress Report June1986 23 DTIC M,% ;,I ECTE ,->0 CT05 1990 DISSTRB 101,STAThmb57 A Approved for public release; 90 10r4t13ed 90 10 04 13-0- .ccession For gi'S 3TCC T\3GRA&I Massachusetts Institute of Technology UxTnounced Laboratory for Computer Science Just ificatio 545 Technology Square Cambridge, MA 02139 Distribution/ 617-253-5851 Availability Codes Avail and/or Dist Special The work reported herein was carried out within the Laboratory for Computer Science, an MIT interdepartmental laboratory. During 1985-86 the principal financial support of the Laboratory has come from the Defense Advanced Research Projects Agency (DARPA). DARPA has been instrumental in supporting most of our research during the last 23 years and is gratefully acknowledged here. Our overall support has come from the following organizations: " Defense Advanced Research Projects Agency; " Department of Energy; " National Institutes of Health; * National Science Foundation; " Office of Naval Research; * United States Air Force; " United States Army Research Office; " MIT controlled IBM funds under an IBM/MIT joint study contract. Other support of a generally smaller level has come from Harris Corporation, Siemens, and Giers. Final assembly and production of this report was done by Paula Vancini with special assistance from Maria Sensale and Mary Weston. Unclassified SECURITY CLASSIFICATION OF THIS PAGE REPORT DOCUMENTATION PAGE la. REPORT SECURITY CLASSIFICATION lb. RESTRICTIVE MARKINGS Unclassified 2a. SECURITY CLASSIFICATION AUTHORITY 3. DISTRIBUTION /AVAILABILITY OF REPORT Approved for public release; distribution SCHEDULE Approved 2b. DECLASSIFICATION/DOWNGRADING is unlimited. 4. PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUMBER(S) MIT/LCS/PR - 23 6a. NAME OF;I PERFORMING ORGANIZATION i6b. OFFICE(ifapplicable) SYMBOL 7a. NAME OF MONITORING ORGANIZATION MIT Lab for Computer Science Office of Naval Research/Dept. of Navy 6c. ADDRESS (City, State, and ZIP Code) 7b. ADDRESS (City, State, and ZIP Code) 545 Technology Square Information Systems Program Cambridge, MA 02139 Arlington, VA 22217 8a. NAME OF FUNDING/SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATIONI (If applicable) DARPA/ DOD 8c. ADDRESS (City, State, and ZIPCode) 10. SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK WORK UNIT 1400 Wilson Blvd. ELEMENT NO. NO. NO. ACCESSION NO. Arlington, VA 22217 11. TITLE (Include Security Classification) MIT Laboratory for Computer Science Progress Report 23 12. PERSONAL AUTHOR(S) Dertouzos, M.L. 13a. TYPE OF REPORT 13b. TIME COVERED 114. DATE OF REPORT (Year, Month, Day) 15. PAGE COUNT Technical/Progress I FROM 7/85 TO 6/86 June 1986 i 292 16. SUPPLEMENTARY NOTATION 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by blck number) FIELD GROUP T SUB-GROUP Computer Architecture, Computer Science, Computer Systems, Electrical Engineering, Networks Theory of Computers, Proarammina Lanauaasc 19. ABSTRACT (Continue on reverse if necessary and identify by block number) Annual Report of Progress made at the MIT Laboratory for Computer Science Under contracts: a.) N00014-83k-0125,Darpa Order 5602/2095 b.) N00014-84k-0059, Darpa Order 4920 20 DISTRIBUTION/AVAILABILITY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFCArION M] UNCLASSIFIED/UNLIMITED 0 SAME AS RPT. 0 OTIC USERS Unclassified 22a, NAME OF RESPONSIBLE INDIVIDUAL 22b. TELEPHONE (Include Area Code) 22c. OFFICE SYMBOL Carol Nicolora i (617) 253-5894 1 1 DD FORM 1473,84 MAR 83 APR edition may be used until exhausted. SECURITY CLASSIFICATION OF THIS PAGE All other editions are obsolete. *153. Gomrnwnt- rktdn Offi-: 1M-807-47 Unclassified INTRODUCTION MAIG1 CLINICAL DECISION .K,.GJ 5 1. Introduction 7 2. An Artificial Intelligence Appro0ch to Clinical Decision Making 7 2.1. Knowledge Representtio'n 10 2.2. Development of a nlfform Knowledge Base 13 2.3. Importing C onents of Existing Reasoning Systems 18 2.4-Repre-entation and Organization of Case-Specific Knowledge 18 2.5. Qualitative Methods of Reasoning 19 2.6. Integration of Al and Decision Analytic Methods 20 2.7. Decision Tree Critiquer 20 2.8. Planning Under Uncertainty 25 3. A Program for the Management of Heart Failure 26 COMMON SYSTEM, \ 35 1. Overview 36 2. Remote In on 36 3. .rogrm Specification 39 4. Service Interfaces 40 5. Future Plans S /,ft 41 COMPUTATION STRUCTURES '/43 1. Introduction 45 2. Personnel 46 3. Multiprocessor Emulation Facility 47 3.1. The Current MEF Hardware and the Circuit Switch 47 3.2. The Packet Switch Development 49 3.3. The Hardware Laboratory and New Equipment 51 4. Tools for Dataflow Experiments 51 4.1. Id Compiler 52 4.2. GITA 53 4.3. U-GITA 54 4.4. MEF-GITA 54 4.5. SITA: A Simulator for the Tagged-Token Machine 55 4.6. Id World 55 5. Experiments on MEF 56 5.1. Dataflow Experiments 56 5.1.1 Token Storage Management 56 5.1.2 Structure Storage Management 57 5.1.3 Work Distribution 57 5.1.4 Limitations of MEF GITA 58 5.2. DisCoRd: Parallel Graph Reduction on the MEF 58 6. Language Research for the Tagged-Token Dataflow 59 Architecture 6.1. Id/83s 59 6.1.1 I-structures in Id/83s 60 6.1.2 Types in ld/83s 61 6.1.3 Garbage Collection Experiments on MEF 63 6.2. Demand-driven Evaluation 64 6.3. Databases and Functional Languages 64 6.3.1 Data Models and Type Structure 65 6.3.2 Modeling State 65 6.3.3 Functional Databases 66 7. Work Under Professor Dennis 67 7.1. The ViM Project 67 7.2. Accomplishments 67 7.3. Compiling for the Static Dataflow Machine 69 7.4. Simulating Applicative Architectures on the Connection 70 Machine DISTRIBUTED COMPUTING SYSTEMS' 79 1. Introduction 80 2. SWIFT 80 3. Residential CATV-Based Data Commu cations 81 4. Long Atomic Transactions 82 5. Resource Management in Pac etworks 84 6. The NETBLT Protocol 85 7. PCMAIL: A.Distribtited Mail System for Personal Computers 86 ,,,,.-NtWork onitoring 88 9. Access to Inter-Organization Computer Networks 89 INFORMATION MECHANICS . 95 1. Introduction 96 2. Cellular Automata Machines 96 3. The CAM-7 Multi ro 96 4. Fl id-.Dy mics Modeling 97 -. Combinatorial Dynamics 97 6. CA '86 97 7. Neural Networks 97 8. STATPHYS-16 98 PROGRAMMING METHODOLOGY 101 1. Summary 103 1.1. Argus 103 2. Evaluation of Argus 104 3. Specificatio o istributed Programs 108 4 i-tiations on Availability in the Presence of Partit' ns 116 4.1. Assumptions and Definitions 117 4.2. Analysis 118 P,,G3 AM,,..,,,,,,M,, ING V ,.,,,..,RA., RESEARC. , 127 1. Introduction ) 128 2. Plans for the Next Year 128 3. Overview of the Boston Community Information System 129 4. The Data Model 131 5. Composite Databases 133 © 6. The Personal Database System 134 7. Database Servers 137 8. Related Work 141 9. Performance and Implementation Statu$ 143 10. Conclusions 144 - EAL TIME SYSTEMS' 155 1. Introduction j) 157 2. Parallel Processing 157 2.1. The Concert Multi rocessor Testbed 157 161 2.3.2.2. CollaborationParallel Lisp tth Other Organizationts 158 162 3. The3.1. LArchit Architect ral Model 161164 3.2. Pr typical L Implementation 164 4. Arc cturalh Building Blocks 165 5. imulation Tools for VLSI 166 5.1.3 Circuit Partitioning 167 5.2. Decoupling the Simulations 170169 // 5.3. PRSIM Performance 6. Schema Developments 171 6.1. Schematic Entry System 172 6.2. Software Organization 7. Database Accelerator 173 8. X-Windows 173 SYSTEMATIC PROGRAM DEVELOPMENT) 183 1. Introduction 184 2. Larch 184 2.1. The Larch Family of S t n Lalguages 186 or for e arch Shared Langoeige 187 2.3. Analysis Tools 188 2.4. Concurrency 188 2.5. Larch Interface Languages 189 3. The Reve Term Rewriting System 190 3.1. Reve 2.4 190 3.2. Unification 191 THEORY OF COMPUTATION, 197 1. Research Overview 199 2. Faculty and Research Associates 199 3. Students and Visitors 209 THEORY OF DISTRIBUTED SYSTEMS 235 1. Individual Progress Reports 236 PUBLICATIONS 247 ADMINISTRATION Academic Staff M. Dertouzos Director R. Rivest Associate Director Administrative Staff P. Anderegg Assistant Administrative Officer A. Chow Fiscal Officer G. Brown Facilities Officer J. Hynes Administrative Officer M. Jones Assistant Administrative Officr M. Sensale Librarian Support Staff L. Cavallaro B. Pierce R. Donahue E. Profirio M. Gibson D. Simmons A. Kekejian P. Vancini T. LoDuca S. Van Norden INTRODUCTION The MIT Laboratory for Computer Science (LCS) is an interdepartmental laboratory .hose principal goal is research in computer science and engineering. Founded in 1963 as Project MAC (for Multiple Access Computer and Machine Aided Cognition), the Laboratory developed the Compatible Time Sharing System (CTSS), one of the first time shared systems in the world, and Multics -- an improved time shared system that introduced several new concepts. These two major developments stimulated research activities in the application of on-line computing to such diverse disciplines as engineering, architecture, mathematics, biology, medicine, library science and management. Since that time, the Laboratory's pursuits expanded, leading to pioneering research in Expert Systems, Computer Networks and Public Cryptography. Today, the Laboratory's research spans a broad front of activities, grouped in four major are a s ' The first such area entitled ' owledge Based Systems involves making programs more intelligent by capturing, representing, and using knowle ge which is specific to the problem domain. Examples are the use of expert medical nowledge for assistance in diagnosis carried out by the Clinical Decision Making Gl up; and the use of solid-state circuit design knowledge for an expert VLSI (very lar( scale integration) design system by the VLSI Design Project. Research in the second and largest area, entitled Machines, Languages, and Systemstrives to discover and understand computing systems at both the hardware and softwa' levels that open new application areas and/or effect sizable improvements in their ease f utilization and cost effectiveness.