A general treatment of dynamic integrity constraints

This paper introduces a general, set-theoretic model for expressing dynamic integrity constraints, i.e., integrity constraints on the state changes that are allowed in a given state space. In a managerial context, such dynamic integrity constraints can be seen as representations of “real world” constraints and business rules. This topic has important practical applications in many business areas. The notions of (direct) transition, reversible and irreversible transition, transition relation, and consistency of a transition relation will be introduced. The expected link with Kripke models (for modal and temporal logics) is also made explicit. Several practical examples of dynamic integrity constraints will illustrate the applicability of the theory. Some important subclasses of dynamic integrity constraints in a database context will be identified, e.g., various forms of cumulativity (which can be regarded as “transitional” inclusion dependencies concerning two different “points in time”), non-decreasing values, integrity constraints on initial and final values, life cycles, changing life cycles, and transition and constant dependencies. Several formal properties of these dependencies will be derived. For instance, it turns out that functional dependencies can be considered as “degenerated” transition dependencies. Also, the distinction between primary keys and alternate keys is reexamined, from a dynamic point of view.     

A Game Theoretic Approach to the Analysis of Dynamic Networks

A model of dynamic networks is introduced which incorporates three kinds of network changes: deletion of nodes (by faults or sabotage), restoration of nodes (by actions of “repair”), and creation of nodes (by actions that extend the network). The antagonism between the operations of deletion and restoration resp. creation is modelled by a game between the two agents “Destructor” and “Constructor”. In this framework of dynamic model-checking, we consider as specifications (“winning conditions” for Constructor) elementary requirements on connectivity of those networks which are reachable from some initial given network. We show some basic results on the (un-)decidability and hardness of dynamic model-checking problems.     

Personalization of internet telephony services for presence with SIP and extended CPL

This paper discusses issues of personalization of presence services in the context of Internet Telephony. Such services take into consideration the willingness and ability of a user to communicate in a network, as well as possibly other factors such as time, address, etc. Via a three-layer service architecture for communications in the session initiation protocol (SIP) standard, presence system basic services and personalized services (personal policies) are clearly separated and discussed. To enrich presence related services, presence information is illustratively extended from the well known “online” and “offline” indicators to a much broader meaning that includes “location”, “lineStatus”, “role”, “availability”, etc. Based on this, the call processing language (CPL) is extended in order to describe presence related personalized services for both call processing systems and presence systems using information such as a person’s presence status, time, address, language, or any of their combinations. A web-based system is designed and implemented to simulate these advanced services. In the implementation, personal policies are programmed by end users via a graphic user interface (GUI) and are automatically translated into extended CPL. The simulation system clearly displays when, where and what CPL policies should be used for the provision of personalized presence services and call processing services. Policy conflicts are also addressed by setting policy priorities in the system.     

A distributed approach for fault detection and diagnosis based on Time Petri Nets

This paper proposes an algorithm for the model based design of a distributed protocol for fault detection and diagnosis for very large systems. The overall process is modeled as different Time Petri Net (TPN) models (each one modeling a local process) that interact with each other via guarded transitions that becomes enabled only when certain conditions (expressed as predicates over the marking of some places) are satisfied (the guard is true). In order to use this broad class of time DES models for fault detection and diagnosis we derive in this paper the timing analysis of the TPN models with guarded transitions. In this paper we also extend the modeling capability of the faults calling some transitions faulty when operations they represent take more or less time than a prescribed time interval corresponding to their normal execution. We consider here that different local agents receive local observation as well as messages from neighboring agents. Each agent estimates the state of the part of the overall process for which it has model and from which it observes events by reconciling observations with model based predictions. We design algorithms that use limited information exchange between agents and that can quickly decide “questions” about “whether and where a fault occurred?” and “whether or not some components of the local processes have operated correctly?”. The algorithms we derive allow each local agent to generate a preliminary diagnosis prior to any communication and we show that after communicating the agents we design recover the global diagnosis that a centralized agent would have derived. The algorithms are component oriented leading to efficiency in computation.     

Sketching space

In this paper, we present a sketch modelling system which we call Stilton. The program resembles a desktop VRML browser, allowing a user to navigate a three-dimensional model in a perspective projection, or panoramic photographs, which the program maps onto the scene as a “floor” and “walls”. We place an imaginary two-dimensional drawing plane in front of the user, and any geometric information that user sketches onto this plane may be reconstructed to form solid objects through an optimisation process. We show how the system can be used to reconstruct geometry from panoramic images, or to add new objects to an existing model. While panoramic imaging can greatly assist with some aspects of site familiarisation and qualitative assessment of a site, without the addition of some foreground geometry they offer only limited utility in a design context. Therefore, we suggest that the system may be of use in “just-in-time” CAD recovery of complex environments, such as shop floors, or construction sites, by recovering objects through sketched overlays, where other methods such as automatic line-retrieval may be impossible. The result of using the system in this manner is the “sketching of space” — sketching out a volume around the user — and once the geometry has been recovered, the designer is free to quickly sketch design ideas into the newly constructed context, or analyse the space around them. Although end-user trials have not, as yet, been undertaken we believe that this implementation may afford a user-interface that is both accessible and robust, and that the rapid growth of pen-computing devices will further stimulate activity in this area.     

A survey of socially interactive robots

This paper reviews “socially interactive robots”: robots for which social human–robot interaction is important. We begin by discussing the context for socially interactive robots, emphasizing the relationship to other research fields and the different forms of “social robots”. We then present a taxonomy of design methods and system components used to build socially interactive robots. Finally, we describe the impact of these robots on humans and discuss open issues. An expanded version of this paper, which contains a survey and taxonomy of current applications, is available as a technical report [T. Fong, I. Nourbakhsh, K. Dautenhahn, A survey of socially interactive robots: concepts, design and applications, Technical Report No. CMU-RI-TR-02-29, Robotics Institute, Carnegie Mellon University, 2002].     

Expert systems in the context of multi-brain systems

In this article, we postulate the possibility of building a four-brain like expert system. For this purpose we have taken ideas from Minsky’s “Society of Mind” some concepts from Brooks and Stein’s “Brains for Bodies” project, and some mechanisms from neurophysiology. In our search for conceptualization of a minimum multi-brain like system oriented to expert systems, we found that: (a) expert systems with blackboard architecture can be seen as primitive topological approaches to multi-brain systems, (b)in our multi-brain like expert systems conception, as in many other expert systems, we feel that we have to impose our external language as their internal language and our external symbols as their internal symbols. These are the kind of entities discussed by philosophers as “What is it like to be a Bat?”. In this context our conception is still a “Batman”. True-cognitive expert systems might be produced in the future if the matters are self constructed internal languages, and its post-hoc knowledge, and (c) in the scope of multi-brain systems, expert systems are not an engineering subject of artificial intelligence (AI) but a substantive subject that goes from philosophical to neurophysiological aspects.     

New Branches, Old Roots: A Study of Methods and Techniques in Web/Hypermedia Systems Design

Despite claims in the literature that “traditional” methods and techniques are inadequate and poorly matched to the demands of the Web design context, the findings from a field survey of Web/hypermedia systems designers in Ireland indicate quite the contrary. in general, the notion of “method” in the traditional sense seems to have been largely displaced by hybrid aggregations of techniques and other method fragments - selected on the basis of usefulness and purposefully blended within an overarching framework of an in-house development process.     

What a histogram can really tell the classifier

This paper presents a simple and efficient clustering technique based on the partitioning of the data histogram. The clustering technique was developed in the context of a study of possible unsupervized classification procedures for multispectral earth imagery. The ultimate goal was on-board data compression, the algorithmic production of thematic maps.

The incoming raw spectral data is first reduced to its two principal (Karhunen-Loêve) components, the histogram of which is then partitioned into natural classes on the sole weight of evidence of the global statistics of the imagery. During the course of the study, it became clear that some connection existed between the proposed philosophy and professor Thom's novel theory of “catastrophes”.⁽¹⁾ A simple metric is added to the histogram topology. The metric uses both Shannon's and Fisher's notions of self information. In the domain of definition of the histogram, zones corresponding to the natural classes become separated by a no man's land, an inter-class zone. Under the same formulation, the metric is “Euclidean” on the class zone, “non-Euclidean”, i.e. “Lorentz” on the inter-class zone. This methodology and the underlying philosophy were tested in practice, and encouraging results were obtained.     

Bane or Boon? What the CEO Really Thinks of MIS

To answer the question, “What do CEOs think about information systems? ” first step back and ask, “What do CEOs normally think about? ”Effective CEOs spend almost all of their time thinking about problems and opportunities, and the information systems department that presents either is sure to get the CEO's attention.     

Retrieval of movie scenes by semantic matrix and automatic feature weight update

A new semantic-based video scene retrieval method is proposed in this paper. Twelve low-level features extracted from a video clip are represented in a genetic chromosome and target videos that user has in mind are retrieved by the interactive genetic algorithm through the feedback iteration. In this procedure, high-level semantic relevance between retrieved videos is accumulated with so-called semantic relevance matrix and semantic frequency matrix for each iteration, and they are combined with an automatic feature weight update scheme to retrieve more target videos at the next iteration. Experiments over 300 movie scene clips extracted from latest well-known movies, showed an user satisfaction of 0.71 at the fourth iteration for eight queries such as “gloominess”, “happiness”, “quietness”, “action”, “conversation”, “explosion”, “war”, and “car chase”.     

On the almost-sure sample stability of systems with randomly time-varying delays

In a large class of multi-loop control systems, many feedback loops are “closed” through a time-shared digital computer, by means of algorithms which require information from sources which are sampled at a rate which is not synchronized with the sampling of the individual “plants”. This mis-synchronization, coupled with variations in the computer's task load caused by “interrupts”, results in a randomly time-varying delay in the closing of the various feedback loops. Consequently, the dynamics of each controlled “plant” in such a system may be modeled by means of a stochastic delay-differential equation. This paper presents some new research results concerning the sample stability, as opposed to statistical, or ensemble stability, of linear stochastic delay-differential equations.     

Color enhancement of highly correlated images. I. Decorrelation and HSI contrast stretches

Conventional enhancements for the color display of multispectral images are based on independent contrast modifications or “stretches” of three input images. This approach is not effective if the image channels are highly correlated or if the image histograms are strongly bimodal or more complex. Any of several procedures that tend to “stretch” color saturation while leaving hue unchanged may better utilize the full range of colors for the display of image information. Two conceptually different enhancements are discussed: the “decorrelation stretch”, based on principal-component (PC) analysis, and the “stretch” of “hue”-“saturation”-intensity (HSI) transformed data. The PC transformation is scene-dependent, but the HSI transformation is invariant. Examples of images enhanced by conventional linear stretches, decorrelation stretch, and by stretches of HSI transformed data are compared. Schematic variation diagrams or two- and three-dimensional histograms are used to illustrate the “decorrelation stretch” method and the effect of the different enhancements.     

“Chaotic relaxation” in concurrently asynchronous neural networks

In this paper we analyze a fundamental issue which directly impacts the scalability of current theoretical neural network models to applicative embodiments, in both software as well as hardware. This pertains to the inherent and unavoidable concurrent asynchronicity of emerging fine-grained computational ensembles and the consequent chaotic manifestations in the absence of proper conditioning. The latter concern is particularly significant since the computational inertia of neural networks in general and our dynamical learning formalisms manifests itself substantially, only in massively parallel hardward—optical, VLSI or opto-electronic. We introduce a mathematical framework for systematically reconditioning additive-type models and derive a neuro-operator, based on the chaotic relaxation paradigm whose resulting dynamics are neither “concurrently” synchronous nor “sequentially” asynchronous. Necessary and sufficient conditions guaranteeing concurrent asynchronous convergence are established in terms of contracting operators. Lyapunov exponents are also computed to characterize the network dynamics and to ensure that throughput-limiting “emergent computational chaos” behavior in models reconditioned with concurrently asynchronous algorithms was eliminated.     

Information requirements of the quality assurance system

The rapid growth in the use of computers in Egypt since 1963 has led to significant changes in the information which is available for decision making and control. This information expansion has taken place against a background in which the information requirements of quality assurance systems were poorly defined. The result has been an “overabundance of irrelevant information”, and no corresponding improvement in the quality of products and services.

Most of the computer applications in the field of quality assurance deal with particular problems, specific organizations, or just guidelines for developing an information system.

On certain level of details, a general model of the quality assurance system could be defined. A corresponding general model of information system for quality assurance is proposed. The model is used for identifying the information requirements of the general quality assurance system and integrating the available applications in the field.     

Permitting updates through views of data bases

Providing different views (logical images of the structure of a data base) to various users creates the problem of determining how update operations expressed in terms of the views should affect the stored form of the data base. For data bases with a relational organization, we indicate the effects of a wide range of update operations on views. We conclude that some operations must be prohibited in order to assure harmonious interactions among data base users, but that many other operations can be allowed even though the structure of the view may differ substantially from the actual structure of the data base. We consider views not only as “windows” through which to see a data base in a particular way, but also as “shades” to conceal and protect information, and as “screens” to intercept any update operations that could leave the stored form of the data base in an unacceptable state.     

Visual surveillance using deformable models of vehicles

This paper presents recent developments to a vision-based traffic surveillance system which relies extensively on the use of geometrical and scene context. Firstly, a highly parametrised 3-D model is reported, able to adopt the shape of a wide variety of different classes of vehicle (e.g. cars, vans, buses etc.), and its subsequent specialisation to a generic car class which accounts for commonly encountered types of car (including saloon, batchback and estate cars). Sample data collected from video images, by means of an interactive tool, have been subjected to principal component analysis (PCA) to define a deformable model having 6 degrees of freedom.

Secondly, a new pose refinement technique using “active” models is described, able to recover both the pose of a rigid object, and the structure of a deformable model; an assessment of its performance is examined in comparison with previously reported “passive” model-based techniques in the context of traffic surveillance. The new method is more stable, and requires fewer iterations, especially when the number of free parameters increases, but shows somewhat poorer convergence.

Typical applications for this work include robot surveillance and navigation tasks.