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."

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."

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.

In a large-scale space, structure is at a significantly larger scale than the observations available at an instant. To learn the structure of a large-scale space from observations, the observer must build a cognitive map of the environment by integrating observations over an extended period of time, inferring spatial structure from perceptions and the effects of actions. The cognitive map representation of large-scale space must account for a mapping, or learning structure from observations, and navigation, or creating and executing a plan to travel from one place to another. Approaches to date tend to be fragile either because they don't build maps; or because they assume nonlocal observations, such as those available in preexisting maps or global coordinate systems, including active landmark beacons and geo-locating satellites. We propose that robust navigation and mapping systems for large-scale space can be developed by adhering to a natural, four-level semantic hierarchy of descriptions for representation, planning, and execution of plans in large-scale space. The four levels are sensorimotor interaction, procedural behaviors, topological mapping, and metric mapping. Effective systems represent the environment, relative to sensors, at all four levels and formulate robust system behavior by moving flexibly between representational levels at run time. We demonstrate our claims in three implemented models: Tour, the Qualnav system simulator, and the NX robot.

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. Third, I examine how the frame of reference is determined for all three cases. Fourth, I look at ambiguities in the use of prepositions and how they can be resolved. 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.

MIT Press.

In Ronald Brachman and Hector Levesque, editors, Readings in Knowledge.’ Representation, pages 467-486. Morgan Kaufmann,

in D Michie (ed.), Expert Systems in the Micro-Electronic Age, pp. 242-270, Edinburgh: Edinburgh University Press