The rationale of powertype-based metamodelling to underpin software development methodologies

Metamodelling provides a way of modelling the rules underpinning not only modelling languages such as UML but also processes. In the context of object-oriented development, we evaluate the conceptual framework used to reason about metamodelling from the different perspectives of methodologist, method engineer and software developer. We propose the use of clabjets and powertype patterns as a solution to avoid the present inconsistencies in the use of a strict metamodelling multi-level hierarchy and demonstrate their efficacy in providing a solid and improved framework for OO-based process (and product) metamodelling. Copyright © 2005, Australian Computer Society, Inc

A foundation for multi-level modelling

Multi-level modelling allows types and instances to be mixed in the same model, however there are several proposals for how meta- models can support this. This paper proposes a meta-circular basis for meta-modelling and shows how it supports two leading approaches to multi-level modelling

Internal transitions of negatively charged magnetoexcitons in quantum dots

We report calculations of oscillator strengths for the far infrared absorption of light by the excitonic complexes Xn- (the excess charge, n, ranging from one to four) confined in quantum dots. The magnetic field is varied in an interval which corresponds to ``filling factors'' between 2 and 3/5. Electron-hole interaction effects are seen in the deviations of the peak positions from the Kohn lines, and in the spreading of the oscillator strengths over a few final states. Transition densities are used as an additional tool to characterize the absorption peaks.Comment: Presented as a poster in the Third Stig Lundqvist Conference on Advancing Frontiers of Condensed Matter Physics: Fundamental Interactions and Excitations in Confined Systems, Trieste, August 11 - 1

Towards an interoperable metamodel suite: size assessment as one input

In recent years, many metamodels have been introduced in the software engi- neering literature and standards. These metamodels vary in their focus across, for example, process, product, organizational and measurement aspects of software development and have typically been developed independently of each other with shared concepts being only accidental. There is thus an increasing concern in the standards communities that possible conicts of structure and semantics between these various metamodels will hinder their widespread adoption. The complexity of these metamodels has also increased significantly and is another barrier in their appreciation. This complexity is compounded when more than one metamodel is used in the lifecycle of a software project. Therefore there is a need to have interoperable metamodels. As a first step towards engendering interoperability and/or possible mergers between metamodels, we examine the size and complexity of various meta- models. To do this, we have used the Rossi and Brinkkemper metrics-based approach to evaluate the size and complexity of several standard metamodels including UML 2.3, BPMN 2.0, ODM, SMM and OSM. The size and complexity of these metamodels is also compared with the previous version of UML, BPMN and Activity diagrams. The comparatively large sizes of BPMN 2.0 and UML 2.3 suggest that future integration with these metamodels might be more difficult than with the other metamodels under study (especially ODM, SSM and OSM)

Comparison of method chunks and method fragments for situational method engineering

Two main candidates for the atomic element to be used in Situational Method Engineering (SME) have been proposed: the “method fragment ” and the “method chunk”. These are examined here in terms of their conceptual integrity and in terms of how they may be used in method construction. Also, parallels are drawn between the two approaches. Secondly, the idea of differentiating an interface from a body has been proposed for method chunks (but not for method fragments). This idea is examined and mappings are constructed between the interface and body concepts of method chunks and the concepts used to describe method fragments. The new ISO/IEC 24744 standard metamodel is used as a conceptual framework to perform these mappings

Comparison of |Q|=1 and |Q|=2 gauge-field configurations on the lattice four-torus

It is known that exactly self-dual gauge-field configurations with topological charge |Q|=1 cannot exist on the untwisted continuum 4-torus. We explore the manifestation of this remarkable fact on the lattice 4-torus for SU(3) using advanced techniques for controlling lattice discretization errors, extending earlier work of De Forcrand et. al. for SU(2). We identify three distinct signals for the instability of |Q|=1 configurations, and show that these manifest themselves early in the cooling process, long before the would-be instanton has shrunk to a size comparable to the lattice discretization threshold. These signals do not appear for our |Q|=2 configurations. This indicates that these signals reflect the truly global nature of the instability, rather than local discretization effects. Monte-Carlo generated SU(3) gauge field configurations are cooled to the self-dual limit using an O(a^4)-improved gauge action chosen to have small but positive O(a^6) errors. This choice prevents lattice discretization errors from destroying instantons provided their size exceeds the dislocation threshold of the cooling algorithm. Lattice discretization errors are evaluated by comparing the O(a^4)-improved gauge-field action with an O(a^4)-improved action constructed from the square of an O(a^4)-improved lattice field-strength tensor, thus having different O(a^6) discretization errors. The number of action-density peaks, the instanton size and the topological charge of configurations is monitored. We observe a fluctuation in the total topological charge of |Q|=1 configurations, and demonstrate that the onset of this unusual behavior corresponds with the disappearance of multiple-peaks in the action density. At the same time discretization errors are minimal.Comment: 12 pages, 9 figures, submitted to Phys. Rev.

An ontology for ISO software engineering standards: 1) Creating the infrastructure

Software engineering standards developed under the auspices of ISO/IEC JTC1's SC7 have been identified as employing terms whose definitions vary significantly between standards. This led to a request in 2012 to investigate the creation of an ontological infrastructure that aims to be a single coherent underpinning for all SC7 standards, present and future. Here, we develop that necessary infrastructure prior to its adoption by SC7 and its implementation (likely 2014). The proposal described here requires, firstly, the identification of a single comprehensive set of definitions, the definitional elements ontology (DEO). For the scope of an individual standard, only a subset of these definitional elements will be needed. Once configured, this definitional subset creates a configured definitional ontology or CDO. Both the DEO and the CDO are essentially foundational ontologies from which a domain-specific ontology known as a SDO or standard domain ontology can be created. Consequently, all such SDOs are conformant to a CDO and hence to the single DEO thus ensuring that all standards use the same ontological base. Standards developed in this fashion will therefore be not only of a higher quality but also, importantly, interoperable. © 2013 Elsevier B.V. All rights reserved

Improving agile software development by the application of method engineering practices

Despite the vast attention and wide acceptance of the newly engineered agile methods for software development, those methods are seldom linked to the goals of software process improvement (SPI), an approach that aims to provide support for significant improvement of both the quality of those methods as well as the resultant software products. In this paper, we propose an extension to agile methods by adding extra characteristics in order for agile methods to better support SPI. We explain how agile methods can gain those extra attributes through the application of a method engineering approach along with our new tool (4-DAT) that assists method engineers and managers in selecting the most appropriate method fragments for their needed agile methods. Finally, we summarize a number of industrial case studies carried out over several years in order to test and improve the efficiency of our theory of adding SPI to an agile methodological approach

Few-anyon systems in a parabolic dot

The energy levels of two and three anyons in a two-dimensional parabolic quantum dot and a perpendicular magnetic field are computed as power series in 1/|J|, where J is the angular momentum. The particles interact repulsively through a coulombic (1/r) potential. In the two-anyon problem, the reached accuracy is better than one part in 10^5. For three anyons, we study the combined effects of anyon statistics and coulomb repulsion in the ``linear'' anyonic states.Comment: LaTeX, 6 pages, 4 postscript figure