Methods are presented 1) to partition or decompose a visual scene into the bodies forming it; 2) to position these bodies in three-dimensional space, by combining two scenes that make a stereoscopic pair; 3) to find the regions or zones of a visual scene that belong to its background; 4) to carry out the isolation of the objects in 1) when the input has inaccuracies. Running computer programs implement the methods and many examples illustrate their behavior. The input is a two-dimensional line-drawing of the scene, assumed to contain three-dimensional bodies possessing flat faces (polyhedra); some of them may be partially occluded. Suggestions are made for extending the work to curved objects. Some comparisons are made with human visual perception.

"Although the problem of determining the minimum cost path through a graph arises naturally in a number of interesting applications, there has been no underlying theory to guide the development of efficient search procedures. Moreover, there is no adequate conceptual framework within which the various ad hoc search strategies proposed to date can be compared. This paper describes how heuristic information from the problem domain can be incorporated into a formal mathematical theory of graph searching and demonstrates an optimality property of a class of search strategies." IEEE Transactions on Systems Science and Cybernetics, SSC-4 (2), 100-107. See also correction: http://dl.acm.org/citation.cfm?id=1056779.

In Proc. 23rd ACM National Conference.

During the past few years there has been a rapid advance in the technology of time-sharing systems and software to permit quick access to large files of structured data. This has led to a growing interest in communicating with computer files directly in a natural language such as English. The natural language systems described in the literature are largely small-scale research vehicles dealing with small data bases of restricted subject scope. Giuliano (1965), among others, has questioned the generalization of these systems to wider universes of discourse. Developments in this area have been reviewed by Simmons (1966), and by Bobrow, Fraser and Quillan (1967).

Simmons has presented a survey of some fifteen experimental question-answering and related systems which have been constructed since 1959. These systems take input questions in natural English (subject to varying constraints) and attempt to answer the questions on the basis of a body of information, called the data base, which is stored inside the computer. This process can be conceptually divided into three phases---syntatic analysis, semantic analysis, and retrieval, as illustrated schematically in Figure 1. The first phase consists of parsing the input sentence into a structure which explicitly represents the grammatical relationships among the words of the sentence. The remaining phase consists of procedures for either retrieving the answer directly from the data base, or else deducing the answer from information contained in the data base.

Cambridge, Mass.: MIT Press

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This paper is a survey of the current machine translation research in the US, Europe and Japan. A short history of machine translation is presented first, followed by an overview of the current research work. Representative examples of a wide range of different approaches adopted by machine translation researchers are presented. These are described in detail along with a discussion of the practicalities of scaling up these approaches for operational environments. In support of this discussion, issues in, and techniques for, evaluating machine translation systems are addressed.

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Nature, 218, 19-22.