Essentially, a connection graph is merely a data structure for a set of clauses indicating possible refutations. The graph itself is not an inference system. To use the graph, one has to introduce operations on the graph. In this paper, we shall describe a method to obtain rewriting rules from the graph, and then to show that these rewriting rules can be used to generate a refutation plan that may correspond to a large number of linear resolution refutations. Using this method, many redundant resolution steps can be avoided.
Optimal Search Strategies for Speech Understanding Control W. A. Woods Bolt Beranek and Newman Inc. Cambridge, MA 02238 Abstract This paper describes two algorithms for finding the optimal interpretation of an unknown utterance in a continuous speech understanding system. These methods guarantee that the first complete interpretation found will be the best scoring interpretation possible. Moreover, unlike other optimal strategies, they do not make finite-state assumptions about the nature of the grammar for the language being recognized. One of the methods, the density method, is especially interesting because it is not an instance of the "optimal" A* algorithm of Hart, Nilsson, and Raphael, and appears to be superior to it in the domains in which it is applicable. The other method, the shortfall method, is an instance of the A* algorithm using a particular heuristic function.
The purpose of this research is to investigate the extent to which knowledge can replace and support search in selecting a chess move and to delineate the issues involved. This has been carried out by constructing a program. PARADISE (PArtern Recognition Applied to Directing SEarch), which finds the best move in tactically sharp middle game positions from the games of chess masters. The actions of the rules post concepts in the data base while the conditions match patterns in the chess position and data base. The program uses the knowledge base to discover plans during static analysis and to guide a small tree search which confirms that a particular plan is best.
This is an informal description of my ideas about using formal logic as a tool for reasoning systems using computers. Introduction The title of this paper contains both the words'mechanized' and'theory'. I want to make the point that the ideas presented here are not only of interest to theoreticians. I believe that any theory of interest to artificial intelligence must be realizable on a computer. I will not present difficult examples.
In the synthesis of a plan or computer program, the problem of achieving several goals simultaneously presents special difficulties, since a plan to achieve one goal may interfere with attaining the others. This paper develops the following strategy: to achieve two goals simultaneously, develop a plan to achieve one of them and then modify that plan to achieve the second as well. A systematic program modification technique is presented to support this strategy. The technique requires the introduction of a special "skeleton model" to represent a changing world that can accommodate modifications in the plan. This skeleton model also provides a novel approach to the "frame problem."
The selection of what to do next is often the hardest part of resource-limited problem solving. In planning problems, there are typically many goals to be achieved in some order. The goals interact with each other in ways which depend both on the order in which they are achieved and on the particular operators which are used to achieve them. A planning program needs to keep its options open because decisions about one part of a plan are likely to have consequences for another part. This paper describes an approach to planning which integrates and extends two strategies termed the least-commitment and the heuristic strategies.
ABSTRACT Computer systems for use by physicians have had limited impact on clinical medicine. When one examines the most common reasons for poor acceptance of medical computing systems, the potential relevance of artificial intelligence techniques becomes evident. This paper proposes design criteria for clinical computing systems and demonstrates their relationship to current research in knowledge engineering. The MYCIN System is used to illustrate the ways in which our research group has attempted to respond to the design criteria cited. My goal is to present design criteria which may encourage the use of computer programs by physicians, and to show that Al offers some particularly pertinent methods for responding to the design criteria outlined.
The first section discusses the importance of having systems that understand the concept of knowledge, and how knowledge is related to action. Section 2 points out some of the special problems that are involved in reasoning about knowledge, and section $ presents a logic of knowledge based on the idea of possible worlds. Section 4 integrates this with a logic of actions and gives an example of reasoning in the combined system. Section 5 makes some concluding comments. I. Introduction One of the most important concepts an intelligent system needs to understand is the concept of knowledge.
ON CLOSED WORLD DATA BASES Raymond Reiter The University of British Columbia Vancouver, British Columbia ABSTRACT Deductive question-answering systems generally evaluate queries under one of two possible assumptions which we in this paper refer to as the open and closed world assumptions. The open world assumption corresponds to the usual first order approach to query evaluation: Given a data base DB and a query Q, the only answers to Q are those which obtain from proofs of Q given DB as hypotheses. Under the closed world assumption, certain answers are admitted as a result of failure to find a proof. More specifically, if no proof of a positive ground literal exists, then the negation of that literal is assumed true. In this paper, we show that closed world evaluation of an arbitrary query may be reduced to open world evaluation of socalled atomic queries.