System operation contracts were introduced by C. Larman as an application of the notion of Design by Contract (DbC) to the description of high-level system operations derived from requirements. A system operation contract specifies an operation in terms of changes induced in the domain. In the Responsibility Driven Development (RDD) process proposed by Larman, operation contracts play an important role in identifying and assigning systems' responsibilities, and help construct a sound design in later phases. Larman's notation for operation contracts is textual. In this thesis, we propose an alternative visual notation for operation contracts. As part of the process for the definition of this visual notation, we extended and clarified some informal aspects of Larman's notation in order to better accurately capture important aspects of system operations. Our extension allows the specification of data constraints, alternatives, and the temporal dimension of created domain objects, in addition to the description of changes in the state and associations of domain objects. The syntax of the visual notation for operation contracts aims to be cognitively effective and to reuse available UML notation. New visual elements were introduced only in the absence of corresponding elements in the UML. Elements reused from the UML are slightly modified to enhance their cognitive effectiveness. The introduced elements, on the other hand, are designed with the goal of not conflicting with the general theme of the UML. We used The Physics of Notations as a general guide and evaluation criteria. The Physics of Notations is a leading evaluation and design theory for visual models in software engineering. We propose a prototype tool (ViOpContract) that implements the proposed visual notation for operation contracts. ViOpContract is an Eclipse plug-in tool that helps to draw and manage visual operation contracts. The tool provides the capability to generate contracts in textual form from visual contracts.

Resources Events Agents (REA) ontology is a profound business modeling ontology that was developed to define the architecture of accounting information systems. Nevertheless, REA did not manage to get the same attention as other business modeling ontologies. One reason of such abandon is the absence of a meaningful visual notation for the ontology, which has resulted in an abstruse ontology to non-academic audience. Another reason for this abandon is the fact that REA does not have a standard formal representation. This has resulted in a humble amount of researches which have focused on defining meta-models of the ontology while neglecting the wider purpose of REA-based information systems development. Consequently, the ontology was deviated away from its original purpose, and rather used in business schools. To solve the aforementioned issues, this research presents a Model Driven Development (MDD) technique in the form of a REA-based Domain Specific Visual Language (DSVL) that is implemented within a modeling and code generation editor. This effort was taken in order to answer the question of “How would a REA-DSVL based tool make the REA ontology implementable in the domain of information systems development?” In order to answer the research question, a design science methodology (DSRM) was implemented as the structure of this research. The DSRM was chosen because this research aims to develop three main artifacts. These are; a meta-model of REA, a visual notation of REA, and a REA-DSVL-based modeling and code generation tool. The first phase of the DSRM was to identify the problems which were mentioned earlier, followed by the requirements identification phase which drew the outline of the; meta-model, the visual notation, and the tool. After that, the development phase was conducted in order to develop the aforementioned artifacts. The editor was then demonstrated using a case study of a local company in Stockholm-Sweden. Finally, the resulted artifacts were evaluated based on the collected requirements and the results from the case study. Based on the analyses of the artifacts and the case study, this research was concluded with the result that a REA-based DSVL tool can help in boosting the planning and analysis phases of the software development lifecycle (SDLC). This is achieved by automating some of the conventional software planning and design tasks, which would lead to more accurate systems’ designs; thus, minimizing the time of the planning and design phases. And it can be achieved by abstracting the direct logic of REA through providing functionalities that help users from different backgrounds (academic and professional) to embrace a business modeling editor rather than an ontology; thus, attracting a wider users base for implementing REA.

There are three main results in this dissertation. The first result is the construction of an abstract visual space for rational numbers mod1, based on the visual primitives, colour, and rational radial direction. Mathematics is performed in this visual notation by defining increasingly refined visual objects from these primitives. In particular, the existence of the Farey tree enumeration of rational numbers mod1 is identified in the texture of a two-dimensional animation. ¶ The second result is a new enumeration of the rational numbers mod1, obtained, and expressed, in abstract visual space, as the visual object coset waves of coset fans on the torus. Its geometry is shown to encode a countably infinite tree structure, whose branches are cosets, nZ+m, where n, m (and k) are integers. These cosets are in geometrical 1-1 correspondence with sequences kn+m, (of denominators) of rational numbers, and with visual subobjects of the torus called coset fans. ¶ The third result is an enumeration in time of the visual hierarchy of the discrete buds of the Mandelbrot boundary by coset waves of coset fans. It is constructed by embedding the circular Farey tree geometrically into the empty internal region of the Mandelbrot set. In particular, coset fans attached to points of the (internal) binary tree index countably infinite sequences of buds on the (external) Mandelbrot boundary.