The Complexity of Reasoning about Spatial Congruence

In the recent literature of Artificial Intelligence, an intensive research effort has been spent, for various algebras of qualitative relations used in the representation of temporal and spatial knowledge, on the problem of classifying the computational complexity of reasoning problems for subsets of algebras. The main purpose of these researches is to describe a restricted set of maximal tractable subalgebras, ideally in an exhaustive fashion with respect to the hosting algebras. In this paper we introduce a novel algebra for reasoning about Spatial Congruence, show that the satisfiability problem in the spatial algebra MC-4 is NP-complete, and present a complete classification of tractability in the algebra, based on the individuation of three maximal tractable subclasses, one containing the basic relations. The three algebras are formed by 14, 10 and 9 relations out of 16 which form the full algebra

A Generic Library of Problem Solving Methods for Scheduling Applications

In this thesis we propose a generic library of scheduling problem-solving methods. As a first approximation, scheduling can be defined as an assignment of jobs and activities to resources and time ranges in accordance with a number of constraints and requirements. In some cases optimisation criteria may also be included in the problem specification. Although, several attempts have been made in the past at developing the libraries of scheduling problem-solvers, these only provide limited coverage. Many lack generality, as they subscribe to a particular scheduling domain. Others simply implement a particular problem-solving technique, which may be applicable only to a subset of the space of scheduling problems. In addition, most of these libraries fail to provide the required degree of depth and precision, which is needed both to obtain a formal account of scheduling problem solving and to provide effective support for development of scheduling applications by reuse. Our library subscribes to the Task-Method-Domain-Application (TMDA) knowledge modelling framework, which provides a structured organisation for the different components of the library. In line with the organisation proposed by TMDA, we first developed a generic scheduling task ontology, which formalises the space of scheduling problems independently of any particular application domain, or problem solving method. Then we constructed a task-specific, but domain independent model of scheduling problem-solving, which generalises from the variety of approaches to scheduling problem-solving, which can be found in literature. The generic nature of this model was demonstrated by constructing seven methods for scheduling, as alternative specialisation of the model. Finally, we validated our library on a number of applications to demonstrate its generic nature and effective support for the analysis and development of scheduling applications

Norbert Wiener and the growth of negative feedback in scientific explanation : with a proposed research program of "cybernetic analysis"

Negative feedback has become ubiquitous in science both as a technique and as a conceptual tool. As a technique, negative feedback has a long history; devices based in its use were made in antiquity. It has only been during the last century, however, that rigorous quantitiative methods have become associated with the applications of negative feedback. These methods originated in communications engineering and during the World War II period spread rapidly to other areas of science where further applications were soon made. During this process of dissemination negative feedback was transformed into a powerful conceptual tool, of general application, having to do with the organization of behavior. The central figure responsible for both the dissemination and transformation of negative feedback was the American mathematician, Norbert Wiener, who, as a child prodigy, had developed graduate level proficiency in science, mathematics and philosophy before he was twenty. Wiener's multidisciplinary background and interests were critically important in allowing him to interact with professionals in many different fields and thereby to disseminate the feedback ideas. Wiener and two colleagues were the authors of the 1943 paper, "Behavior, Purpose and Teleology," which stimulated a number of interdisciplinary meetings. These meetings were important in spreading the feedback concepts to the different disciplines. Participating in these meetings were, among others, Gregory Bateson, Wolfgang Miler, Margaret Mead, Warren S. McCulloch, F. S. C. Northrop, John von Neumann and Wiener. The successful assimilation of feedback by the various disciplines in spite of the problems associated with modern discipline specialization provides a lesson in how these problems may be overcome. In the case of feedback, the climate for its assimilation was made considerably more receptive by concurrent developments in computer science and neurophysiology which mutually reinforced the robotic view. The role of negative feedback in scientific research and the significance of this role have not yet been fully identified. Such an identification must be made in order to evaluate the historical events which led to the assimilation of negative feedback. I attempt to define the role of negative feedback in scientific research in terms of a program called "cybernetic analysis." This program develops the behavioral and functional roles of negative feedback in terms of "adaptive goal-directed behavior"; such behavior occurs when a system can maintain a certain state or tend toward a certain state even while being disturbed by external influences. This behavior is exhibited both by organisms and by mechanical devices controlled by negative feedback. Until now the idea that systems could be directed toward an end has been unacceptable because goal-directedness has been associated with the outdated notions of teleology and final cause. The ability of negative feedback to account for goal-directedness mechanistically not only challenges the view that organisms alone can exhibit such behavior, but also stands to revise the scientific view of goaldirectedness in general. With the new legitimacy of both adaptive and non-adaptive goal-directedness, the path is opened for more effective analysis of scientific problems. Despite the great value of Wiener's Cybernetics in focusing attention on the many new robotic developments of the World War II period, it tended to obscure many of the critical points made in the earlier (1943) paper with regard to the role of negative feedback in scientific explanation. The term "cybernetics" came to be a great source of confusion because of Wiener's initial presentation, a presentation which mirrored many of the earlier events in the interdisciplinary meetings which led to the writing of the work. It is suggested here that the term "cybernetic analysis" be used to designate that type of problem analysis which utilizes the hypothesis of a negative feedback mechanism to account for adaptive goaldirected behavior. The use of the term "cybernetics" in this manner will not only succinctly identify one of the great unnamed developments in science, but give the word renewed meaning in terms of the literal roots from which Wiener first derived it

Third Conference on Artificial Intelligence for Space Applications, part 1

The application of artificial intelligence to spacecraft and aerospace systems is discussed. Expert systems, robotics, space station automation, fault diagnostics, parallel processing, knowledge representation, scheduling, man-machine interfaces and neural nets are among the topics discussed