The capabilities for representing and reasoning about three-dimensional (3-D) objects are essential for knowledge-based, 3-D photointerpretation systems that combine domain knowledge with image processing, as demonstrated by 3- D Mosaic and ACRONYM. A practical framework for geometric representation and reasoning must incorporate projections between a two-dimensional (2-D) image and a 3-D scene, shape and surface properties of objects, and geometric and topological relationships between objects. In addition, it should allow easy modification and extension of the system's domain knowledge and be flexible enough to organize its reasoning efficiently to take advantage of the current available knowledge. This system uses frames to represent objects such as buildings and walls, geometric features such as lines and planes, and geometric relationships such as parallel lines.

In this article, principles involving the intrinsic, deictic, and extrinsic use of spatial prepositions are examined from linguistic, psychological, and AI approaches. First, I define some important terms. Second, those prepositions which permit intrinsic, deictic, and extrinsic use are specified. Finally, I introduce the natural language dialog system CITYTOUR, which can cope with the intrinsic, deictic, and extrinsic use of spatial prepositions, and compare it with the approaches dealt with in the previous sections as well as to some other AI systems.

A guest editorial describing the special issue on spatial reasoning: "We conceive of space as a completely empty, infinite, three-dimensional, isotropic, disembodied receptacle distinct from the earth or any object that might be located on the earth, one that is capable of housing not only things but also such incorporeal mathematical entities as points and infinite straight lines. Such a strange idea -especially if it were taken to describe something that exists in this world-was unthinkable before the seventeenth century; yet not even Galileo fully accepted the idea of such a world as real. For him, a "straight line" was still bound to the earth's surface. The transformation that led to the reification of geometry, though basically one of attitude and perception rather than of empirical observation, profoundly affected the course of science."

This is Part 2 of a two-part article and discusses issues of tort liability and the use of computers in the courtroom. [The legal dimensions of topics covered in this part are given comprehensive attention by the author in Tort Adjudication and the Emergence of Artificial Intelligence Software, 21 Suffolk University Law Review 623 (1987)]. Part 1 of this article, which appeared in the Spring 1988 issue of AI Magazine, discussed steps that developers of AI systems can take to protect their efforts, and the attendant legal ambiguities that must eventually be addressed in order to clarify the scope of such protection. Part 2 explores the prospect of AI systems as subjects of litigation.

It was felt that the AIM Szolovits responding, and "Uncertainty approaches, augmenting explanations

A guest editorial describing the special issue on spatial reasoning: "We conceive of space as a completely empty, infinite, three-dimensional, isotropic, disembodied receptacle distinct from the earth or any object that might be located on the earth, one that is capable of housing not only things but also such incorporeal mathematical entities as points and infinite straight lines. Such a strange idea -especially if it were taken to describe something that exists in this world-was unthinkable before the seventeenth century; yet not even Galileo fully accepted the idea of such a world as real. For him, a "straight line" was still bound to the earth's surface. Not until Newton was the task of "geometrization of the world" ... completed. The transformation that led to the reification of geometry, though basically one of attitude and perception rather than of empirical observation, profoundly affected the course of science."

There was a six-way tie were losses to International Master's, for first with 5.5 points between: and there were two draws against International Grandmaster Mikhail players rated over 2500, (one an International Tal (a former world champion), International Master). Grandmaster Sergey Kudrin, From previous tournaments rated FIDE Master Michael Brooks, International by FIDE, the international chess federation, Master James Rizzitano, International Hitech has achieved a performance Master Calvin Blocker, and worthy of a FIDE rating. However, International Grandmaster Leonid at present FIDE is declining to Shamkovich. Hitech has met every points were: National Master Hitech, qualification but one for achieving a International Grandmaster Maxim rating--it is not a human. If Hitech Dlugy, International Grandmaster were eligible for a rating, its FIDE rating Walter Browne, International Grandmaster would be 2350, which would qualify Arthur Bisguier, and nine others.

Our guest editor is Avi Kak, of Purdue University. We also round out the issue with the final installment of Steven Frank's Swartout, on an AAAIsponsored Planning Workshop, held last year. "open-ended" (i.e., almost any aspect of the experienced world might be Book reviews should be submitted to the Book Review Editor, Bruce D'Ambrosio, Computer Science Department, Oregon State University, Corvallis, OR 97331 (503) 754.4466 Advertising rates and media kits are available upon request from AI Magazine, 445 Burgess Drive, Menlo Park, CA 94025 Telephone (415) 328.3123

Commercial AI Trends Seen at AAAI-Extracting the Knowledge of 87 8(4): (Winter 19871, 93-95.

Moravec has interests in computer animation and three dimensional graphics. He has produced illustrations and films presenting progress in the other work and published in the areas of mobile robots, computer vision, robots and the future, orbital skyhooks, switching networks, and three dimensional Keith M. Andress, coauthor of "Evidence Accumulation and Flow of Control in graphics a Hierarchical Spatial Reasoning System, " is a research associate in the Robot Vision Lab at Purdue University His research interests are in formalisms for Gudula Retz-Schmidt received her accumulation of evidence, expert systems, and computer vision. He can be Master degree (Dipl.-Inform) Practitioners Should Know about the Law. Part Two" is an attorney practicing Benjamin J. Kuipers, coauthor of William Swartout, editor of "Summary with Nutter, McClennen & Fish, "Navigation and Mapping in Large-Report on DARPA Santa Cruz One International Place, Boston, Massachusetts Scale Space" is an associate professor Workshop on Planning" is a senior 02210-2699. His research Framework for Representing and Reasoning research interests include qualitative interests include explanation of about Three-Dimensional reasoning about physical mechanisms expert systems, natural language generation, Objects for Vision" is group leader of and qualitative representations and expert system architectures, the Sensory Intelligence Group in the learning strategies for spatial knowledge.