Showing papers on "Representation (systemics) published in 1979"

Multiple representations of the body within the primary somatosensory cortex of primates.

Abstract: Microelectrode mapping experiments indicate that the classical primary somatosensory cortex of monkeys consists of as many as four separate body representations rather than just one. Two complete body surface representations occupy cortical fields 3b and 1. In addition, area 2 contains an orderly representation of predominantly "deep" body tissues. Area 3a may constitute a fourth representation.

The internal representation of solid shape with respect to vision

Abstract: It is argued that the internal model of any object must take the form of a function, such that for any intended action the resulting reafference is predictable. This function can be derived explicitly for the case of visual perception of rigid bodies by ambulant observers. The function depends on physical causation, not physiology; consequently, one can make a priori statements about possible internal models. A posteriori it seems likely that the orientation sensitive units described by Hubel and Wiesel constitute a physiological substrate subserving the extraction of the invariants of this function. The function is used to define a measure for the visual complexity of solid shape. Relations with Gestalt theories of perception are discussed.

Associative Networks: The Representation and Use of Knowledge by Computers

Abstract: Upon opening this book and leafing through the pages, one gets the impression of an important compendium. The fourteen articles provide good coverage of semantic networks and related systems for representing knowledge. Their average length of 33 pages is long enough to give each author reasonable scope, yet short enough to permit a variety of viewpoints to be expressed in a single volume. The editor should be commended for his efforts in putting together a wellorganized book instead of just another collection of unrelated papers.

The Delegate Theory of Representation

Abstract: The delegate theory of representation posits that legislators ought to reflect purposively the preferences of their constituents. We show that this form of representation does take place on salient issues when the theory's two fundamental conditions are fulfilled simultaneously. First, legislators must think of themselves as delegates. Second, constituencies must provide consistent cues regarding district preferences to their representatives. The absence of either or both conditions seriously disrupts delegated representation.

On representation and approximation of nonlinear systems: Part II: Discrete time

Abstract: In a discrete-time framework any nonlinear system can be approximated with arbitrarily small error by a Volterra series and also by a “sandwich” system.

An examination of a frame-structured representation system

Abstract: The Unit Package is an interactive knowledge representation system with representations for individuals, classes, indefinite individuals, and abstractions. Links between the nodes are structured with explicit definitional roles, types of inheritance, defaults, and various data formats. This paper presents the general ideas of the Unit Package and compares it with other current knowledge representation languages. The Unit Package was created for a hierarchical planning application, and is now in use by several AI projects.

A procedural semantics for semantic networks

Abstract: In this chapter, we describe an approach to the representation of knowledge that formalizes traditional semantic network concepts within a procedural framework. The basic entities of the representation are classes and (binary) relations, and their semantics are provided by a small set of programs. Two organizational principles are offered by the representation: the IS-A and PART-OF hierarchies, which allow the specification of generalization and whole-part relationships, respectively. The concept of a metaclass is also introduced (i.e., a class of classes), and it is shown how it can be used to explain certain features of the representation within itself. Properties of classes are then classified as structural or assertional and it is demonstrated that each type must have different inheritance rules, which can be expressed quite simply in the representation. Finally, a representation for programs is proposed in terms of the IS-A and PART-OF hierarchies. The benefits of such an organization of programs and the relationship between the representation and others such as KRL and FRL are also discussed.

On the Structure of Knowledge - A Morphology of Metal Models in a Man-Machine System Context,

Abstract: : The report is a working paper which describes an illustrates different forms of mental representations of the functional properties of a physical system as found in a man-machine system context. The outlines of a morphology of such models are discussed in terms of different levels of abstraction related to physical form; physical function; functional structure; abstract function; and functional meaning or purpose. The distinction between deterministic quantitative models based on variables and relations, and causal, qualitative models based on objects or functions which have properties and interact by events, is discussed. The dependency of the different levels of abstraction upon representation of aspects of the material basis of the system versus aspects of human reasons for the existence of the system is described. Finally, the different strategies of humans to cope with complexity is briefly discussed in the context of the morphology. (Author)

Prepositional attitudes: Fregean representation and simulative reasoning

Abstract: This paper describes briefly a general notation that has been constructed for representing information about propositions! attitudes, and a method that is being developed for using this notation to reason about such Information. The notation is Fregean in spirit, and is based on McCarthy's first-order theory of individual concepts and propositions, extended to permit adequate representation of Iterated propositional attitudes, and with a semantically simpler representation of quantified propositions and "definite-description" concepts of Individuals. The notation provides a systematic and Intuitively motivated way of dealing with apparent failures of extensionality and quantification into Intentional constructions. The reasoning method is knowledge-based, and uses a program's own ordinary inferential apparatus to "simulate" the reasoning of other intelligent organisms. The method thus avoids any need for redundant re-representation of Information about propositions at higher levels in the hierarchy of concepts, and provides a natural approach to making realistic inferences about the propositions! attitudes of others.

Object Migration and Authentication

Abstract: When typed objects migrate in virtual memory, onto off-ine storage, or among the nodes of a network, the type managers must relinguish control over the object representation and state. In this paper we present a mechanism which allows a type manager to authenticate and reinstantiate migrated objects. This mechanism also solves some problems stemming from the hierarchical structure of the system itself. The mechanism is based on a combination of cryptographic techniques using (nondistributable) centralized, secret keys, and data redundancy which characterizes the object representation and state.

Steady turning of two-wheeled vehicles

Abstract: Steady turning of two-wheeled vehicles is examined in terms of a theory accommodating large lean angles and a realistic representation of wheel-roadway interaction. Quantitative and qualitative relationships between rider and vehicle behavior are explored in detail, and a parameter study is performed with a view to facilitating design. Paper No. 790187.

Internal representation of a process, fault diagnosis and fault correction

Abstract: This paper reports on an investigation into the relationship between the internal representation of a process on the one hand and on the other, control behaviour when diagnosing and correcting faults. The subjects were 87 process operator trainees, performing certain tasks in a simulated process control situation. Two modes of internal representation are distinguished: a more verbal or abstract mode of the functioning of the process (the mental model) and a more visual or concrete mode of the structure of the process (the mental image). It is concluded that the mental model probably plays an important role in fault correction and in the verification process in diagnosing faults, while the mental image seems to play an important role in the search for information in the process of diagnosis. Some implications for operator training are discussed.

On Behavioral Theories of Reference

Abstract: Efforts to bare the psychonomic nature of the semantic reference (representation) relation have been remarkably scanty; in fact, the only contemporary account developed with any care is the one proposed by Osgood. However, not even Osgood has looked deeply at the difficulties that beset any attempt to analyze reference in terms of common effects appropriately shared by a symbol and its significate.

Speech acts and multiple environments

Abstract: This brief paper outlines joint work that implies a view of the explication of Speech Acts different from those current in AI It is exploratory at present, but we intend that it should lead to programs as soon as possible We propose a system that engages in dialogue with a human user so as to discuss others and in doing so, interprets the appropriate communicative force of the user's utterances The three key features of the explication of communicative force presented are: 1 multiple environments: the ability to interpret an expression or a description relative to some particular knowledge, eg relative to the beliefs of one person about another It is a generalization of the computer science approach to expression evaluation, using the notion of an environment to fix the interpretation of names occurring in the expression 2 dual knowledge representation: an "experiential" representation is used to memorize sentences or other episodes (exemplified by pseudo-tests, or PTs), while a frame-type representation is used to memorize knowledge needed more generally for reasoning 3 a least effort principle of understanding: considered to be a language universal, which requires (a) that the system maintain as much representation as possible in the frame-like forms, rather than in PTs, and (b) that the system maintain a highly redundant representation in the PTs, achieved by a process we call percolation of belief

Digital system for changing the rate of recorded speech

Abstract: Representation of a speech signal by its short-time Fourier transform and the application of this representation to the problem of time compression and expansion of speech are presented. A time-frequency representation for linear time-varying systems is applied to a model for speech production to formulate a quasi-stationary representation for the speech waveform. This representation has the property that simple time scaling of the parameters of the representation corresponds to changing the rate of the speech. Given a real speech signal, short-time Fourier analysis provides a technique for estimating and modifying these parameters. The results of the theoretical analysis are used to design a high-quality speech rate-change system which are simulated on a general-purpose digital mini-computer.