Showing papers on "Representation (systemics) published in 1988"

A stochastic map for uncertain spatial relationships

Abstract: In this paper we will describe a representation for spatial relationships which makes explicit their inherent uncertainty. We will show ways to manipulate them to obtain estimates of relationships and associated uncertainties not explicitly given, and show how decisions to sense or act can be made a priori based on those estimates. We will show how new constraint information, usually obtained by measurement, can be used to update the world model of relationships consistently, and in some situations, optimally. The framework we describe relies only on well-known state estimation methods.

Object Oriented Systems Analysis: Modeling the World in Data

Abstract: 1. Why Information Modeling? 2. Basic Ideas. 3. Objects. 4. Attributes. 5. Relationships. 6. Constructions Involving Many Objects. 7. Representation of the Informal Method. 8. Techniques. 9. The Role of the Information Model in System Development. Appendix A: Tape Robot Information Model. Appendix B: Tables and Columns: A Model for Shared Real-time Data. References.

Representing monotone operators by convex functions

Abstract: Vl e transform the representation of monotone operators due to Krauss to get a representation of monotone operators in terms of the subdifferentials of convex functions on the product of the space and its duat The convex functions representing maximal monotone operators satisfY a minimality condition.

The Primacy of Experience and the Politics of Method

Abstract: Knowledge is rooted in experience and requires a form for its representation. Since all forms of representation constrain what can be represented, they can only partially represent what we know. Forms of representation not only constrain representation, they limit what we seek. As a result, socialization in method is a process that shapes what we can know and influences what we value. At base it is a political undertaking. This article addresses the politics of method and its effects on the character of educational research.

Designing documentation to compensate for delocalized plans

Abstract: Conceptual representation methods play a significant role in facilitating the software process. Recent studies explore and clarify the use of these representations and their impact on progress.

The Science of Design: Creating the Artificial

Abstract: This chapter contains sections titled: The Logic of Design: Fixed Alternatives, Paradoxes of Imperative Logic, Reduction to Declarative Logic, Computing the Optimum, Finding Satisfactory Actions, The Logic of Design: Finding Alternatives, Means-Ends Analysis, The Logic of Search, Design as Resource Allocation, An Example from Highway Design, Schemes for Guiding Search, The Shape of the Design: Hierarchy, The Generator-Test Cycle, Process as a Determinant of Style, Representation of the Design, Problem Solving as Change in Representation, Spatial Representation, The Taxonomy of Representation, Summary—Topics in The Theory of Design, Role of Design in the Life of the Mind

Representation of Mechanical Behavior in the Presence of Changing Internal Structure

Abstract: The paper is concerned with the representation of the relationship that exists, for a given material and temperature and for small deformations, between histories of applied stress and the observed strain and the accompanying changes in internal structure of the material. Emphasis is given to creep damage in metals as a vehicle for illustration of the main ideas introduced in the paper. In particular, the role played by irreducible even rank tensors in the representation of internal structure is discussed and clarified. The restrictions placed by thermodynamics on constitutive equations are considered and the use of potentials in these equations is examined and criticized.

“Knowing” vs “seeing”. problems of the plane representation of space geometry figures

Abstract: There is necessarily a loss of information when moving from a geometrical object to its drawing, but pupils (even sixth graders) frequently have the illusion that they can, thanks to a drawing sufficiently sophisticated and close to the object, make a representation of it in which there is no ambiguity at all.

Categorical representation of facial expressions by 7-month-old infants.

Abstract: Categorical perception, demonstrated as reduced discrimination of within-category relative to between-category differences in stimuli, has been found in a variety of perceptual domains in adults. To examine the development of categorical perception in the domain of facial expression processing, we used behavioral and event-related potential (ERP) methods to assess discrimination of within-category (happy-happy) and between-category (happy-sad) differences in facial expressions in 7-month-old infants. Data from a visual paired-comparison test and recordings of attention-sensitive ERPs showed no discrimination of facial expressions in the within-category condition whereas reliable discrimination was observed in the between-category condition. The results also showed that face-sensitive ERPs over occipital-temporal scalp (P400) were attenuated in the within-category condition relative to the between-category condition, suggesting a potential neural basis for the reduced within-category sensitivity. Together, these results suggest that the neural systems underlying categorical representation of facial expressions emerge during the early stages of postnatal development, before acquisition of language.

Large hierarchical object recognition using libraries of parameterized model sub-parts

Abstract: A description is given of the development of a model-based vision system that utilizes hierarchies of both object structure and object scale. The focus of the research is to use these hierarchies to achieve robust recognition based on effective organization and indexing schemes for model libraries. The goal of the system is to recognize parameterized instances of nonrigid model objects contained in a large knowledge base, despite the presence of noise and occlusion. The approach presented is to develop an object shape representation that incorporates a component subpart hierarchy, to allow for efficient and correct indexing into an automatically generated model library as well as for relative parametrization among subparts, and a scale hierarchy, to allow for a general to specific recognition procedure. The implemented system uses a representation based on significant contour curvature changes and recognition engine based on geometric constraints of feature properties. Examples of the system's performance are given, followed by an analysis of the results. >

A compositional approach to superimposition

Abstract: A general definition of the notion of superimposition is presented. We show that previous constructions under the same name can be seen as special cases of our definition. We consider several properties of superimposition definable in our terms, notably the nonfreezing property. We also consider a syntactic representation of our construct in CSP

Construction of the octree approximating a three-dimensional object by using multiple views

Abstract: A fast, efficient, algorithm that processes polyhedral cones from views of an object to produce an octree representation of the object is proposed. A polyhedral cone defined by both a viewpoint and a polygonal contour of the object in the image for each view always contains the object. Thus the common region of the cones for multiple views is considered to be an approximating one of the object. The octree representation controls all cubic regions in three-dimensional space as a set of nodes with a hierarchical description in positioning, and therefore is suitable for registration of the common region. The computational complexity of the algorithm is directly proportional to the common region surface area and exponentially proportional to the finest resolution level of the octree. The calculation time of the algorithm is determined for illustrative examples of three-dimensional objects. >

Representation of Three‐Dimensional Space in the Vestibular, Oculomotor, and Visual Systems

Abstract: Anatomists have long been fascinated by the arrangement of the semicircular canals, especially as there are only minor variations in size and orientation over a wide variety of species. Every skull that survives, still has the arrangement of the bony part of the labyrinths even long after all traces of its living contents have vanished. The art and technique of preserving not only the bony but also the membranous part of the labyrinths is presented in Gray's The Labyrinths of Animals (1907-1908)' in which more than 70 plates of stereoscopic photographs document the exact three-dimensional anatomy of the membranous labyrinths of various species (FIG. 1). In the first monograph about the vestibular system, Fundamentals of the Theory of Motion Sensation (1875)* Ernst Mach considered several aspects of vestibular physiology that have only recently been explored again. One is multisensory interaction, the other, how direction is coded within the sense of motion. FIGURE 2 shows his schematic drawing of the canals and their spatial arrangement. Physiology in the last century relied mostly on behavioral studies after selective lesions. In 1830 Flourens3 wrote about performing selective canal lesions in pigeons. He accurately described the instability of head movements in the plane of the lesioned canals, but gave very little thought to its interpretation. Experimental work on the labyrinths reached a climax with the techniques of Ewald (1892); who invented and skillfully performed the technique of canal plugging. As shown in FIGURE 3, the idea is to block any fluid movement or pressure build-up across the cupula during angular acceleration without interfering with the hair cells or the afferent nerve. When this is done successfully, the animals do not exhibit spontaneous or pathological nystagmus. Only after single-neuron recordings posed new questions and required new interpretations were some of the above-mentioned techniques virtually reinvented to explore pathophysiological mechanisms. Money and Scott5 reintroduced canalplugging as an experimental tool, and Simpson6 took up the art of creating labyrinthine casts (FIG. 4). Measurements of exact canal configurations and effective muscle pulling directions exist only for a few animals7 FIGURE 5 shows such measurements, using the rabbit as a lateral-eyed animal and the cat as a frontal-eyed animal.' One immediately sees that canals and muscles are approximately aligned, but that their orientations are by no means identical. It is important to note that such deviations are not just the outcome of statistical variations, but are systematic. As a result, if the vestibulo-ocular

Levels of representation in verbal number production

Abstract: ABSTRACT This article reports a single case study of a brain-damaged subject who presented with impaired performance on tasks involving production of verbal numbers (i.e., numbers in the form of words, such as eighty-six). Lexical errors occurred in spoken production but not in written production. Syntactic errors, however, occurred in both production modes. This pattern of performance provides empirical support for assumptions about the componential structure of the normal number processing system.

A hierarchical boundary model for solid object representation

Abstract: A new hierarchical model for solid object representation is described. This model, called a hierarchical face adjacency hypergraph (HFAH), is based on a relational description of the object boundary, called a face adjacency hypergraph (FAH), which considers faces as the primary topological entities defining the object boundary. The HFAH consists of a hierarchy of FAHs describing the decomposition of the boundary of an object into form features. In this paper the HFAH is described together with its internal encoding structure. Two basic transformations, called refinement and abstraction, are defined on the hierarchical model; these allow effective and efficient modifications of the hierarchical boundary model.