Computational and qualitative aspects of evolution of curves driven by curvature and external force

We propose a direct method for solving the evolution of plane curves satisfying the geometric equation v=(x,k,) where v is the normal velocity, k and are the curvature and tangential angle of a plane curve R² at a point x. We derive and analyze the governing system of partial differential equations for the curvature, tangential angle, local length and position vector of an evolving family of plane curves. The governing equations include a nontrivial tangential velocity functional yielding uniform redistribution of grid points along the evolving family of curves preventing thus numerically computed solutions from forming various instabilities. We also propose a full space-time discretization of the governing system of equations and study its experimental order of convergence. Several computational examples of evolution of plane curves driven by curvature and external force as well as the geodesic curvatures driven evolution of curves on various complex surfaces are presented in this paper.     

Tight bounds for oblivious routing in the hypercube

We prove that in anyN-node communication network with maximum degreed, any deterministic oblivious algorithm for routing an arbitrary permutation requires (N/d) parallel communication steps in the worst case. This is an improvement upon the (N/d ^3/2) bound obtained by Borodin and Hopcroft. For theN-node hypercube, in particular, we show a matching upper bound by exhibiting a deterministic oblivious algorithm that routes any permutation in (N/logN) steps. The best previously known upper bound was (N). Our algorithm may be practical for smallN (up to about 2¹⁴ nodes).C. Kaklamanis was supported in part by NSF Grant NSF-CCR-87-04513. T. Tsantilas was supported in part by NSF Grants NSF-DCR-86-00379 and NSF-CCR-89-02500.     

Software engineering programmes are not computer science programmes

Programmes in Software Engineering have become a source of contention in many universities. Some Computer Science departments, many of which have used that phrase to describe individual courses for decades, claim software engineering as part of their discipline. However, Engineering faculties claim Software Engineering as a new speciality in the family of engineering disciplines. This paper discusses the differences between traditional computer science programmes and most engineering programmes and argues that we need programmes that follow the traditional engineering approach to professional education and educate engineers whose speciality within engineering is software construction. One such programme is described.     

Axiomatic semantics of R-schemas and verification of graphic programs

We propose an approach to verification of programs in a graphic language in the programming R-technology and introduce an axiomatic semantics of R-schemas and of graphic Pascal. We justify the advantages of graphic representation of programs for correctness proving and describe a support system for this approach under RAFOS and MS-DOS.Translated from Kibernetika, No. 1, pp. 21–27, January–February, 1990.     

An operational model for structuring the requirements generation process

Product quality is directly related to how well that product meets the customers needs and intents. Therefore, the ability to capture customer requirements correctly and succinctly is paramount. Unfortunately, within most software development frameworks requirements elicitation, recording and evaluation are some of the more ill-defined and least structured activities. To help address such inadequacies, we propose a requirements generation model (RGM) that (a) decomposes the conventional requirements analysis phase into sub-phases which focus and refine requirement generation activities, (b) bounds and structures those activities to promote a more effective generation process, and (c) implements a monitoring methodology to assist in detecting deviations from well-defined procedures intended to support the generation of requirements that meet the customers intent. The RGM incorporates lessons learned from a preliminary study that concentrated on identifying where and how miscommunication and requirements omission occur. An industry study (also reported in this paper) attests to the effectiveness of the RGM. The results of that study indicate that the RGM helps (a) reduce the late discovery of requirements, (b) reduce the slippage in milestone completion dates, and (c) increase customer and management satisfaction levels.     

Is a GigaLIP Fast Enough?

The capability of large, data-intensive expert systems is determined not only by the cleverness and expertise of their knowledge manipulation algorithms and methods but also by the fundamental speeds of the computer systems upon which they are implemented. To date, logical inferences per second (LIPS) is used as the power metric of the knowledge processing capacity of an expert system implementation. We show why this simplistic metric is misleading. We relate the power metrics for conventional computer systems to LIPS and demonstrate wide discrepancies. We review the power of today's largest conventional mainframes, such as the IBM 3090/400 and the Cray Research Cray-2 and forecast the expected power of mainframes and specialized processors in the coming decade.     

A Micro corona motor fabricated by a SU-8 built-on X-ray mask

A micro corona motor was fabricated using a membraneless built-on X-ray mask. Sharp stator electrodes of this motor ionize air molecules and ionized charges transfer onto the rotor surface, resulting in rotating rotor motions by Coulomb forces. For good performance, the stators electrodes should be wide (axial) and have sharp tips. Therefore, X-ray lithography was adopted for precise, high aspect ratio characteristics. To avoid the fabrication difficulty of a membrane X-ray mask, a built-on X-ray mask (conformal mask) technique was employed with negative toned SU-8 photoresist. SU-8 features X-ray fabrication compatibility, X-ray transparency and a large range of thickness. This technique may be suitable for fast fabrication of prototypes or very tall structures, which can be largely affected by printing gaps. For the X-ray built-on mask, 20 m SU-8 was patterned and 8 m gold absorber was electroplated on top of the 300 m PMMA resist. Tests showed good quality pattern transfer from the SU-8 pattern and smooth sidewalls.The authors would like to thank the National Science Foundation, Grant DMI-0115527, Manufacturing Machines and Equipment Program, Division of Design, Manufacture, and Industrial Innovation, and Atoz CompuNet Ltd. for support for this work. We also acknowledge partial support from Center for Nano and Molecular Science and Technology and Welch foundation in The University of Texas at Austin.     

What if computers could think?

The question whether or not computers can think was first asked in print by Alan Turing in his seminal 1950 article. In order to avoid defining what a computer is or what thinking is, Turing resorts to the imitation game which is a test that allows us to determine whether or not a machine can think. That is, if an interrogator is unable to tell whether responses to his questions come from a human being or from a machine, the machine is imitating a human being so well that it has to be acknowledged that these responses result from its thinking. However, then as now, it is not an indisputable claim that machines could think, and an unceasing stream of papers discussing the validity of the test proves this point. There are many arguments in favour of, as well as against, the claims borne by the test, and Turing himself discusses some of them. In his view, there are mice possible objections to the concept of a thinking machine, which he eventually dismisses as weak, irrelevant, or plain false. However, as he admits, he can present no very convincing arguments of a positive nature to support my views. If I had I should not have taken such pains to point out the fallacies in contrary views.     

A criterion for a-stability of linear multistep integration formulae

Summary Two easy-to-check conditions are given which, together, are sufficient and almost necessary forA-stability of linear multistep integration formulae. As an example, these conditions are applied to the two-parameter family of all two-step methods which are at least second-order accurate.

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Zusammenfassung Es werden zwei leicht nachprüfbare Bedingungen hergeleitet, welche fürA-Stabilität von linearen Mehrschrittverfahren hinreichend und fast notwendig sind. Als Beispiel werden diese Bedingungen auf die zweiparametrige Klasse aller Zweischrittverfahren von mindestens zweiter Ordnung angewendet.

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With 1 Figure     

Partitioned data objects in distributed databases

In many distributed databases locality of reference is crucial to achieve acceptable performance. However, the purpose of data distribution is to spread the data among several remote sites. One way to solve this contradiction is to use partitioned data techniques. Instead of accessing the entire data, a site works on a fraction that is made locally available, thereby increasing the site's autonomy. We present a theory of partitioned data that formalizes the concept and establishes the basis to develop a correctness criterion and a concurrency control protocol for partitioned databases. Set-serializability is proposed as a correctness criterion and we suggest an implementation that integrates partitioned and non-partitioned data. To complete this study, the policies required in a real implementation are also analyzed. Recommended by: Hector Garcia-Molina     

The impact of artificial intelligence on leisure

Two views of AI in leisure and the work-place and two views of society are discussed. There is a conceptualisation of AI systems enhancing people in their work and leisure and another of AI automata which tends to degrade and replace human activity. Researchers tend to resolve into Optimists who work within a micro-sociological view and see AI systems as inevitable and beneficent. Others are Pessimists who adopt a macro-sociological view and see AI in its automata role and deliterious social consequences. These polarised perspectives must be integrated as only enhancing AI is socially acceptable.     

Computing spanning line segments in three dimensions

A set of spanning line segments in a polyhedronP preserves the property of intersection; that is, a plane intersectsP if and only if it also intersects . This paper gives a linear time algorithm for constructing for a polyhedron withN extreme vertices. IfN is odd, the algorithm is optimal in yielding [N/2] + 1 spanning line segments. IfN is even, it gives (N/2) + 1, which is optimal in some cases and nearly optimal in others.     

Regions-of-Interest and Spatial Layout for Content-Based Image Retrieval

To date most content-based image retrieval (CBIR) techniques rely on global attributes such as color or texture histograms which tend to ignore the spatial composition of the image. In this paper, we present an alternative image retrieval system based on the principle that it is the user who is most qualified to specify the query content and not the computer. With our system, the user can select multiple regions-of-interest and can specify the relevance of their spatial layout in the retrieval process. We also derive similarity bounds on histogram distances for pruning the database search. This experimental system was found to be superior to global indexing techniques as measured by statistical sampling of multiple users' satisfaction ratings.     

A bidirectional shortest-path algorithm with good average-case behavior

The two-terminal shortest-path problem asks for the shortest directed path from a specified nodes to a specified noded in a complete directed graphG onn nodes, where each edge has a nonnegative length. We show that if the length of each edge is chosen independently from the exponential distribution, and adjacency lists at each node are sorted by length, then a priority-queue implementation of Dijkstra's unidirectional search algorithm has the expected running time (n logn). We present a bidirectional search algorithm that has expected running time (n logn). These results are generalized to apply to a wide class of edge-length distributions, and to sparse graphs. If adjacency lists are not sorted, bidirectional search has the expected running time (an) on graphs of average degreea, as compared with (an) for unidirectional search.     

A Philosophical Approach to the Concept of Data Model: Is a Data Model, in Fact, a Model?

The design of the database is crucial to the process of designing almost any Information System (IS) and involves two clearly identifiable key concepts: schema and data model, the latter allowing us to define the former. Nevertheless, the term model is commonly applied indistinctly to both, the confusion arising from the fact that in Software Engineering (SE), unlike in formal or empirical sciences, the notion of model has a double meaning of which we are not always aware. If we take our idea of model directly from empirical sciences, then the schema of a database would actually be a model, whereas the data model would be a set of tools allowing us to define such a schema.The present paper discusses the meaning of model in the area of Software Engineering from a philosophical point of view, an important topic for the confusion arising directly affects other debates where model is a key concept. We would also suggest that the need for a philosophical discussion on the concept of data model is a further argument in favour of institutionalizing a new area of knowledge, which could be called: Philosophy of Engineering.     

A market-driven approach to teaching software components engineering

The emergence of software component standards and tools for creating software components is leading to an increasing number of software component developers. Traditional software engineering education, however, emphasizes methods for developing large software packages. It is not clear whether such methods are appropriate for developing components. New techniques may be needed to teach the skills necessary for component development. We identify two skills software developers need to successfully develop components, which are not emphasized in traditional software engineering education: (a) uncovering multiple-customer domain semantics; and (b) making explicit multiple-customer framework semantics. Both skills are multiple constraint satisfaction problems. We further argue that training students to produce and market components in a simulated software components marketplace – rather than the more conventional classroom teaching + component homework assignments/projects – is an effective way of teaching such skills. We then describe an environment we created called SofTrade that simulates a components market and allows students to acquire the necessary skills. We provide a detailed case study of how a student component-producer team used market feedback to determine domain and framework semantics. We end by discussing the importance of market-driven approaches for teaching software components engineering and how such approaches fit into existing software engineering curricula.     

A Web‐based multi‐agent system for interpreting medical images

A difficult problem in medical image interpretation is that for every image type such as xray and every body organ such as heart, there exist specific solutions that do not allow for generalization. Just collecting all the specific solutions will not achieve the vision of a computerized physician. To address this problem, we develop an intelligent agent approach based on the concept of active fusion and agentoriented programming. The advantage of agentoriented programming is that it combines the benefits of objectoriented programming and expert system. Following this approach, we develop a Webbased multiagent system for interpreting medical images. The system is composed of two major types of intelligent agents: radiologist agents and patient representative agents. A radiologist agent decomposes the image interpretation task into smaller subtasks, uses multiple agents to solve the subtasks, and combines the solutions to the subtasks intelligently to solve the image interpretation problem. A patient representative agent takes questions from the user (usually a patient) through a Webbased interface, asks for multiple opinions from radiologist agents in interpreting a given set of images, and then integrates the opinions for the user. In addition, a patient representative agent can answer questions based on the information in a medical information database. To maximize the satisfaction that patients receive, the patient representative agents must be as informative and timely as communicating with a human. With an efficient pseudonatural language processing, a knowledge base in XML, and user communication through Microsoft Agent, the patient representative agents can answer questions effectively.     

Deterministic sequential functions

The simple rational partial functions accepted by generalized sequential machines are shown to coincide with the compositions _P ^–1 , where _P consists of the prefix codings. The rational functions accepted by generalized sequential machines are proved to coincide with the compositions _P ^–1 , where is the family of endmarkers and is the family of removals of endmarkers. (The compositions are read from left to right). We also show that _P ^–1 is the family of the subsequential functions.This work was partially supported by the Esprit Basic Research Action Working Group No. 3166 ASMICS, the CNRS and the Academy of Finland     

The role of “craft language” in learning “Waza”

The role of craft language in the process of teaching (learning) Waza (skill) will be discussed from the perspective of human intelligence.It may be said that the ultimate goal of learning Waza in any Japanese traditional performance is not the perfect reproduction of the teaching (learning) process of Waza. In fact, a special metaphorical language (craft language) is used, which has the effect of encouraging the learner to activate his creative imagination. It is through this activity that the he learns his own habitus (Kata).It is suggested that, in considering the difference of function between natural human intelligence and artificial intelligence, attention should be paid to the imaginative activity of the learner as being an essential factor for mastering Kata.This article is a modified English version of Chapter 5 of my bookWaza kara shiru (Learning from Skill), Tokyo University Press, 1987, pp. 93–105.