MIT Reports to the President 1994-95

The Intelligent Room is a new facility constructed during the past year for work on Human Computer Interaction (HCI). The work aims to develop a computational infrastructure that is aware of people, their actions, and their goals through the use of vision and sound understanding. During the first year, students of Professors Brooks, Lozano-Perez and Stein have developed systems that enables presenters to use speech and gesture to navigate through a presentation prepared on the World Wide Web and to use gesture to assign video sources to monitors. Other software from Dr. Victor Zue's group at the Laboratory for Computer Science and from Jim Hollan's group at University of New Mexico have been integrated into the Room.

Software Agents

Professor Stein's group also works on software and information agents. Mr. Michael Coen's SodaBot/SodaBotL is a software agent environment and construction system designed to facilitate the rapid prototyping and deployment of personal and application-based software agents, as well as communities of semi-autonomous associate systems.

Prior to SodaBot, building agents has generally involved a multi-layered approach ranging from low-level "system-hacking'' (e.g. of mailers, networks, etc.) to high-level application development (e.g., a meeting scheduler), and everything in between. Each layers can require a substantial amount of independent implementation and debugging. Additionally, it can be difficult to distribute new agents: they tend to be site-specific in intricate ways, and disconnecting them from their local dependencies can be technically involved.

Mr. Mark Torrance's "Active Notebook'' is a tool that organizes collected information according to a user's personal conceptual taxonomy. Over the next year, Active Notebook will be expanded to better facilitate groupware applications.

Learning from Precedents and Knowledge-Based Retrieval

Professor Winston's group has concentrated recently on developing representations that enable learning and reasoning by analogy. One important component of this research concerns the representation of change. This work, led by Dr. Gary Borchardt, is grounded in the key insight that there is much to be gained by viewing the world from a transition-centered perspective, rather than a state-centered perspective. From the transition-centered perspective, transitions cause transitions. Accordingly, the transition space representation focuses on what is changing rather than on the static properties of things.

During the past year, work has commenced on a second version of the IMPACT system, which uses the transition centered representation to reason about events and causality in complex domains such as manufacturing and transportation. When completed, this implementation of the IMPACT system will analyze simple, written descriptions of events and their surrounding context and use the analysis to identify occurrences of larger, encompassing events, predict possible consequences, offer possible explanations, and describe plausible, finer-grained realizations of events.

Work on the IMPACT system forms one component of a larger effort focused on the development of "Associate Systems,'' or programs that help humans gather information about urgent situations, identify and evaluate possible courses of action, and see selected courses of action through to completion. To this end, Dr. Boris Katz has been developing the START natural language query retrieval system. During the past year, a geography and climate knowledge base was constructed for START, enabling the system to answer thousands of question variants relating to ten topic areas for six countries of interest.

SCIENTIFIC AND ENGINEERING REASONING

Intelligent Simulation

The research of the Project for Mathematics and Computation (Project MaC), under the direction of Professors Abelson and Sussman, is working to demonstrate breakthrough applications that exploit new computer representations and reasoning mechanisms that they have developed. These mechanisms enable intelligent systems to autonomously design, monitor, and understand complex physical systems through appropriate mixtures of numerical computing, symbolic computing, and knowledge-based methods. They call this mixed approach intelligent simulation.

Systems incorporating intelligent simulation can automatically prepare numerical experiments from high-level domain descriptions. They automatically select and configure appropriate numerical methods. They actively monitor numerical and physical experiments. They automatically analyze the results of such experiments, using domain knowledge to interpret the numerical results, and they report these results to their human users in high-level qualitative terms. In favorable cases intelligent simulation programs can automatically configure special-purpose hardware for efficient execution of computationally demanding numerical experiments.

The group has demonstrated the basic capabilities of intelligent simulation systems. They have implemented computer programs that interpret numerical simulations of nonlinear systems, automatically producing summary descriptions similar to those in the published literature.

Recently, the group has also demonstrated that intelligent simulation can help in creating dynamically stabilized structures. Such structures will be sensitive and active, incorporating networks of high-performance

controllers. They have constructed and demonstrated a prototype column that is actively stabilized by piezo-electric actuators. This column supports 5.6 more load than a passive column of the same size could support. The have also demonstrated a truss bridge that uses actively stabilized members to support greater loads than would be possible without active control.

Over the last four years, five of the group's recent graduates have received National Young Investigator awards, largely based on their work on the development and application of intelligent simulation technology. Professor Jack Wisdom, a collaborator with the group, was awarded a MacArthur Fellowship, partly on the basis of work done here.

Model Based Reasoning Systems

Professor Davis, Dr. Shrobe, and their associates are building knowledge-based systems that use models of structure, function, and causality to perform a wide range of problem solving and reasoning tasks. Their systems reason about how devices work and how they fail in a manner similar to an experienced engineer. This is an important advance in the art of knowledge-based systems construction, because it provides the system with a more fundamental understanding of the device than is possible using traditional approaches.

Recent work is focused on understanding how things work in domains that include simple mechanical devices and mechanistic explanations of biological phenomena. Examples of understanding include the ability to produce descriptions of device behavior from a description of their structure, the ability to predict behavior under unusual circumstances, and the ability to redesign to fit those new circumstances.

Professor Davis has also been leading the Intelligent Information Infrastructure project, which is concerned with the next generation of ideas and software to support the National Information Infrastructure. The basic assumption is that the National Information Infrastructure should have intelligence embedded into it, allowing it to understand the information it is carrying and enabling it to provide the foundation for new ways to gather, organize, and transmit knowledge, as well as new ways to operate organizations to take advantage of new knowledge structures.

The members of the project have built a variety of systems, including the publication/distribution system used by the White House Office of Media affairs, in use routinely since January 20, 1993 to distribute OMA publications nationally and internationally, and an on-line surveying system used to determine the size and character of the audience receiving the documents. They have also developed and used the START system to provide a natural-language based information resource.

COMPUTATIONAL INFRASTRUCTURE

Symbolic Parallel Architectures

The Symbolic Parallel Architecture group, under the direction of Dr. Knight, has been developing technology for the next generation of parallel computer systems. The group is developing, for example, compilers that automatically feed back experience in running code for use in the layout and compilation process. Work on extremely low power computing using reversible logic approaches also continues, with funding in place for implementing the first fully reversible computer system using the group's low power technology. The Abacus SIMD vision processor component has been fabricated, and is undergoing initial testing. Abacus is a designed for high-speed processor-per-pixel image handling for early vision applications. Finally, chip-to-chip freespace signaling technologies are under development for use in novel self-assembling arrays of processors. Such processor chip arrays are under study for applications in sensor and effector systems, as well as for implementing simple, local communication for modeling physical systems.

Concurrent VLSI Architecture

The Concurrent VLSI Architecture Group, under the direction of Professor Dally, develops techniques for applying VLSI technology to solve information-processing problems. The group has been developing the M-Machine, an experimental parallel computer that tests new concepts for the control of multiple arithmetic units, interprocessor communication, and memory addressing. During the past year, the group has completed most of the register-transfer-level design of the M-Machine's multi-ALU processor (MAP) chip. Circuit design and layout of portions of the chip have been performed in collaboration with the Microelectronics Center of North Carolina (MCNC). With collaborators at the California Institute of Technology, they have been adapting the Multiflow compiler to generate parallel code for the M-Machine, and they have been writing an operating system that provides coherent shared memory in software.

The group has also been developing the Reliable Router, a multicomputer network component. The Reliable Router demonstrates new algorithms for adaptive routing and fault tolerance in interconnection networks. It also demonstrates new circuit techniques for simultaneous bidirectional signalling (sending bits in both directions simultaneously over one wire) and plesiochronous synchronization.

Finally, the group has been using the J-Machine, an experimental fine-grain parallel computer, to study the dynamics of interconnection network queueing behavior. Several studies were performed to explore technologies for multithreaded processors involving register file organization and thread scheduling, and a parallel compilation method based on a theory of data shapes is under development.

Patrick Henry Winston

MIT Reports to the President 1994-95