Carl Hewitt

IJCAI Conference 1991 Conference Paper

Multiple Approaches to Multiple Agent Problem Solving James Hendler (Chair)

• Danny Bobrow
• Les Gasser
• Carl Hewitt
• Marvin

AIJ Journal 1991 Journal Article

Open Information Systems Semantics for distributed artificial intelligence

• Carl Hewitt

Distributed Artificial Intelligence (henceforth called DAI) deals with issues of large-scale Open Systems (i. e. systems which are always subject to unanticipated outcomes in their operation and which can receive new information from outside themselves at any time). Open Information Systems (henceforth called OIS) are Open Systems that are implemented using digital storage, operations, and communications technology. OIS Semantics aims to provide a scientific foundation for understanding such large-scale OIS projects and for developing new technology. The literature of DAI speaks of many important concepts such as commitment, conflict, negotiation, cooperation, distributed problem solving, representation, etc. However there is currently no framework for comparing the usage of such concepts in one publication with usage in other publications. Open Information System Semantics (henceforth called OIS Semantics) is a step toward remedying this problem by providing a framework which integrates methods from Sociology with methods from Concurrent Systems Science into a foundation that provides a framework for analyzing previous work in DAI and a powerful foundation for its further development. Deduction, one of the most powerful and well-understood methods for information systems, has recently been applied to foundational issues in DAI thereby raising important new issues and problems above and beyond those of applying deduction to the problems of classical AI. OIS Semantics provides answers to many important questions about the uses of deduction in OIS. It provides a characterization of Deduction that encompasses Nth-Order Logics, Meta-theories, Modal Logics, Circumscription, Default Logic, Autoepistemic Logic, Restricted Scope Nonmonotonic Logics, etc. OIS Semantics develops the concept of Deductive Indecision as a fundamental aspect of Deductive systems, thereby characterizing the scope and limits of Deduction for operational and representational activities in OIS. Negotiations play a fundamental role in OIS Semantics. They are creative processes that go beyond the capabilities of Deduction. OIS Semantics characterizes the role of Negotiation as a powerful method for increasing understanding of large-scale OIS projects. The ambitious goal of OIS Semantics for DAI is to provide an integrated foundation for Sociology and Concurrent Systems Science. This paper provides a snapshot of where we currently stand in the process of developing these foundations

AAAI Conference 1983 Conference Paper

Analyzing the Roles of Descriptions and Actions in Open Systems / 162

• Carl Hewitt

This paper analyzes relationships between the roles of descriptions and actions in large scale, open ended, geographically distributed, concurrent systems. Rather than atempt to deal with the complexities and ambiguities of currently implemented descriptive languages, we concentrate our analysis on what can be expressed in the underlying frameworks such as the lambda calculus and first order logic. By this means we conclude that descriptions and actions complement one another; neither being sufficient unto itself. This paper provides a basis to begin the analysis of the very subtle relationships that hold between descriptions and actions in Open Systems.

AAAI Conference 1980 Conference Paper

Knowledge Embedding in the Description System Omega

• Carl Hewitt

AIJ Journal 1977 Journal Article

Viewing control structures as patterns of passing messages

• Carl Hewitt

The purpose of this paper is to discuss some organizational aspects of programs using the actor model of computation. In this paper we present an approach to modelling intelligence in terms of a society of communicating knowledge-based problem-solving experts. In turn each of the experts can be viewed as a society that can be further decomposed in the same way until the primitive actors of the system are reached. We are investigating the nature of the communication mechanisms needed for effective problem-solving by a society of experts and the conventions of civilized discourse that make this possible. In this way we hope eventually to develop a framework adequate for the discussion of the central issues of problem-solving involving parallel versus serial processing and centralization versus decentralization of control and information storage. This paper demonstrates how actor message passing can be used to understand control structures as patterns of passing messages in serial processing. This paper is a pre-requisite for successors which treat issues of parallelism and communication within the framework established here. The ability to analyze or synthesize any kind of control structure as a pattern of passing messages among the members of a society provides an important tool for understanding control structures. Ultimately, we hope to be able to characterize various control structures in common use by societies in terms of patterns of passing messages. This paper makes a small step in this direction by showing how to characterize familiar control structures such as iteration and recursion in these terms.

IJCAI Conference 1969 Conference Paper

PLANNER: A Language for Proving Theorems in Robots

• Carl Hewitt