The 14th Overture Workshop: Towards Analytical Tool Chains

This report contains the proceedings from the 14th Overture workshop organized in connection with the Formal Methods 2016 symposium. This includes nine papers describing different technological progress in relation to the Overture/VDM tool support and its connection with other tools such as Crescendo, Symphony, INTO-CPS, TASTE and ViennaTalk

Utilizando CORBA para distribuir aplicaciones intensivas en cálculo

Actualmente se están utilizando supercomputadores para resolver problemas intensivos en cálculo tales como las previsiones meteorológicas, el aprendizaje de redes neuronales artificiales o incluso aplicaciones lúdicas como el ajedrez. El uso de esta tecnología queda limitado a las grandes corporaciones con medios financieros suficientes como para abordar la adquisición de tales ordenadores. La distribución del cálculo entre varios ordenadores es una solución más barata para aquellos casos en los que la aplicación es susceptible de ser distribuida. De hecho, es la única solución para muchas empresas que no pueden adquirir supercomputadores y que sin embargo soportan aplicaciones que precisan de mucha potencia de cálculo (por ejemplo, el análisis de imágenes). En este artículo mostraremos cómo utilizando un middelware, CORBA (Common Object Request Broker Architecture), y una implementación concreta de este, DST (Distributed Smalltalk), es posible distribuir una aplicación entre varios ordenadores de una manera elegante y escalable y cómo el trabajo cooperativo de varios ordenadores disminuye significativamente el tiempo total de cómputo. Creemos que esta forma de distribución puede solucionar muchos de los problemas de tiempos de ejecución con los que se enfrentan actualmente las empresas de desarrollo softwar

1957-2007: 50 Years of Higher Order Programming Languages

Fifty years ago one of the greatest breakthroughs in computer programming and in the history of computers happened – the appearance of FORTRAN, the first higher-order programming language. From that time until now hundreds of programming languages were invented, different programming paradigms were defined, all with the main goal to make computer programming easier and closer to as many people as possible. Many battles were fought among scientists as well as among developers around concepts of programming, programming languages and paradigms. It can be said that programming paradigms and programming languages were very often a trigger for many changes and improvements in computer science as well as in computer industry. Definitely, computer programming is one of the cornerstones of computer science. Today there are many tools that give a help in the process of programming, but there is still a programming tasks that can be solved only manually. Therefore, programming is still one of the most creative parts of interaction with computers. Programmers should chose programming language in accordance to task they have to solve, but very often, they chose it in accordance to their personal preferences, their beliefs and many other subjective reasons. Nevertheless, the market of programming languages can be merciless to languages as history was merciless to some people, even whole nations. Programming languages and developers get born, live and die leaving more or less tracks and successors, and not always the best survives. The history of programming languages is closely connected to the history of computers and computer science itself. Every single thing from one of them has its reflexions onto the other. This paper gives a short overview of last fifty years of computer programming and computer programming languages, but also gives many ideas that influenced other aspects of computer science. Particularly, programming paradigms are described, their intentions and goals, as well as the most of the significant languages of all paradigms

Entwicklung eines verteilbaren und kooperativ nutzbaren objektorientierten CAAD-Produktmodellierkerns

Der Fokus des Projektes liegt auf einer besseren Unterstützung der kooperativen Aspekte im Bauwerksentwurf und der Anwendung von ComponentWare-Techniken in der Architektur des Entwurfssystems. Es muß festgestellt werden, daß die Kooperation der Beteiligten im Entwurfsprozeß von Bauwerken durch die heute praktizierten Datenaustauschverfahren nicht oder nur unbefriedigend unterstützt wird und das keine Lösung dieses Problems durch die Weiterentwicklung von filebasierten Datenaustauschformaten zu erwarten ist. Im Rahmen des Projektes wird mit einer CORBA-Umgebung für Smalltalk-80 ein verteilbares Objektsystem realisiert. Als Architektur des Systems wurde eine hybride Herangehensweise gewählt, bei der allgemeine Informationen auf einem zentralen Server verwaltet werden und die eigentlichen Projektinformationen bei Bedarf repliziert werden. Wie allgemein in GroupWare - orientierten Systemen notwendig, müssen effektive Mechanismen der Nebenläufigkeitskontrolle und zur Sperrung bestimmter Modellbereiche realisiert werden. Wichtig ist für kooperative Entwurfssysteme die Systemunterstützung der Beseitigung der Folgen von kollidierenden Entwurfsintensionen durch die Bearbeiter. Dazu werden unter anderem Remote-Pointer-Mechanismen realisiert. In Abhängigkeit von der Rolle eines Bearbeiters werden diesem Sichten auf des Objektmodell (Partialmodelle) zugeordnet. Es werden Mechanismen zur Autorisierung des Zugriffs auf Partialmodelle implementiert, zu diesem Zweck erfolgt eine Nutzerauthentifizierung. Beziehungen zwischen Partialmodellen werden durch eine spezielle Relation im Objektsystem abgebildet. Die Konzeption des Objektsystems lehnt sich an die PREPLAN-Philosophie an. Das impliziert die Unterstützung von Entwurfshandlungen sowohl in Bottom-Up- als auch in Top-Down - Richtung. Benutzer können das Objektsystem um eigene Klassen erweitern bzw. existierende Klassen modifizieren und Attribute mit Defaultwerten belegen, um das System inkrementell mit Domänenwissen anreichern zu können. Von großer Bedeutung für kooperative Entwurfssysteme sind eine Versionsverwaltung und die Bereitstellung von Undo - und Redo - Mechanismen. Es ist möglich, multimediale Daten im Objektmodell abzulegen und diese in Abhängigkeit von ihrem Format wiederzugeben bzw. zu bearbeiten. Das beschriebene System befindet sich derzeit in der Implementierung

Logic programming in the context of multiparadigm programming: the Oz experience

Oz is a multiparadigm language that supports logic programming as one of its major paradigms. A multiparadigm language is designed to support different programming paradigms (logic, functional, constraint, object-oriented, sequential, concurrent, etc.) with equal ease. This article has two goals: to give a tutorial of logic programming in Oz and to show how logic programming fits naturally into the wider context of multiparadigm programming. Our experience shows that there are two classes of problems, which we call algorithmic and search problems, for which logic programming can help formulate practical solutions. Algorithmic problems have known efficient algorithms. Search problems do not have known efficient algorithms but can be solved with search. The Oz support for logic programming targets these two problem classes specifically, using the concepts needed for each. This is in contrast to the Prolog approach, which targets both classes with one set of concepts, which results in less than optimal support for each class. To explain the essential difference between algorithmic and search programs, we define the Oz execution model. This model subsumes both concurrent logic programming (committed-choice-style) and search-based logic programming (Prolog-style). Instead of Horn clause syntax, Oz has a simple, fully compositional, higher-order syntax that accommodates the abilities of the language. We conclude with lessons learned from this work, a brief history of Oz, and many entry points into the Oz literature.Comment: 48 pages, to appear in the journal "Theory and Practice of Logic Programming

Agent Based Modeling in Land-Use and Land-Cover Change Studies

Agent based models (ABM) for land use and cover change (LUCC) holds the promise to provide new insight into the processes and patterns of the human and biophysical interactions in ways that have never been explored. Advances in computer technology make it possible to run almost infinite numbers of simulations with multiple heterogeneously shaped actors that reciprocally interact via vertical and horizontal power lines on various levels. Based upon an extensive literature review the basic components for such exercises are explored and discussed. This resulted in a systematic representation of these components consisting of: (1) Spatial static input data, (2) Actor and Actor-group static input data, (3) Spatial dynamic input, (4) Actor and Actor-group dynamic input data, (5) the model with the rules describing the rules, (6) Spatial static output, (7) Actor and Actor-group static output, (8) Dynamic output of Actor behaviour changes, (9) Dynamic output of actor-group behavioural changes, (10) Dynamic output of spatial patterns, (11) Dynamic output of temporal patterns. This representation proves to be epistemologically useful in the analysis of the relationships between the ABM LUCC components. In this paper, this representation is also used to enumerate the strengths and limitations of agent based modelling in LUCC

Computer-aided investigation of interaction mediated by an AR-enabled wearable interface

Dierker A. Computer-aided investigation of interaction mediated by an AR-enabled wearable interface. Bielefeld: Universitätsbibliothek Bielefeld; 2012.This thesis provides an approach on facilitating the analysis of nonverbal behaviour during human-human interaction. Thereby, much of the work that researchers do starting with experiment control, data acquisition, tagging and finally the analysis of the data is alleviated. For this, software and hardware techniques are used as sensor technology, machine learning, object tracking, data processing, visualisation and Augmented Reality. These are combined into an Augmented-Reality-enabled Interception Interface (ARbInI), a modular wearable interface for two users. The interface mediates the users’ interaction thereby intercepting and influencing it. The ARbInI interface consists of two identical setups of sensors and displays, which are mutually coupled. Combining cameras and microphones with sensors, the system offers to record rich multimodal interaction cues in an efficient way. The recorded data can be analysed online and offline for interaction features (e. g. head gestures in head movements, objects in joint attention, speech times) using integrated machine-learning approaches. The classified features can be tagged in the data. For a detailed analysis, the recorded multimodal data is transferred automatically into file bundles loadable in a standard annotation tool where the data can be further tagged by hand. For statistic analyses of the complete multimodal corpus, a toolbox for use in a standard statistics program allows to directly import the corpus and to automate the analysis of multimodal and complex relationships between arbitrary data types. When using the optional multimodal Augmented Reality techniques integrated into ARbInI, the camera records exactly what the participant can see and nothing more or less. The following additional advantages can be used during the experiment: (a) the experiment can be controlled by using the auditory or visual displays thereby ensuring controlled experimental conditions, (b) the experiment can be disturbed, thus offering to investigate how problems in interaction are discovered and solved, and (c) the experiment can be enhanced by interactively comprising the behaviour of the user thereby offering to investigate how users cope with novel interaction channels. This thesis introduces criteria for the design of scenarios in which interaction analysis can benefit from the experimentation interface and presents a set of scenarios. These scenarios are applied in several empirical studies thereby collecting multimodal corpora that particularly include head gestures. The capabilities of computer-aided interaction analysis for the investigation of speech, visual attention and head movements are illustrated on this empirical data. The effects of the head-mounted display (HMD) are evaluated thoroughly in two studies. The results show that the HMD users need more head movements to achieve the same shift of gaze direction and perform less head gestures with slower velocity and fewer repetitions compared to non-HMD users. From this, a reduced willingness to perform head movements if not necessary can be concluded. Moreover, compensation strategies are established like leaning backwards to enlarge the field of view, and increasing the number of utterances or changing the reference to objects to compensate for the absence of mutual eye contact. Two studies investigate the interaction while actively inducing misunderstandings. The participants here use compensation strategies like multiple verification questions and arbitrary gaze movements. Additionally, an enhancement method that highlights the visual attention of the interaction partner is evaluated in a search task. The results show a significantly shorter reaction time and fewer errors