this paper I shall make a case for a dynamic semiotics. I list a set of phenomena that are difficult to understand in standard theories, and suggest a model borrowed from theories of complex dynamic systems. Since such theories rely on processes of self-organization that often defy analytical treatment, I use small computational models for assessing the empirical consequences of the theories.

Defect reports generated for faults found during testing provide a rich source of information regarding problematic phrases used in requirements documents. These reports indicate that faults often derive from instances of ambiguous, incorrect or otherwise deficient language. In this paper, we report on a method combining elements of linguistic theory and information retrieval to guide the discovery of problematic phrases throughout a requirements specification, using defect reports and correction requests generated during testing to seed our detection process. We found that phrases known from these materials to be problematic have occurrence properties in requirements documents that both allow the direction of resources to prioritize their correction, and generate insights characterizing more general locations of difficulty within the requirements. Our findings lead to some recommendations for more efficiently and effectively managing certain natural language issues in the creation and maintenance of requirements specifications. 1.

Partial Reductive Paraphrase (PRP) is a method for constructing explications, a specific kind of definition, for use in requirements documents. Explications avoid common weaknesses of definitions produced by other methods and encourage effective representation of the information most critical to the application domain at hand, allowing better understanding on the part of requirements users. This paper introduces PRP and demonstrates how it is used to construct explications of concepts and present them for accessibility to users. PRP explications are provided for concepts drawn from industrial requirements documents and are then evaluated relative to analogous definitions produced by other methods. The PRP explications are shown to be free of specific faults that otherwise result. Finally, means by which PRP can be integrated into the requirements process are addressed. 1.

this paper is that past failures and countermeasures are imbedded in present-day work arrangements, communication, and artifacts. These phenomena are reified versions of past labor (Latour 1994). A synchronic structural analysis must therefore be supplemented with a diachronic narrative analysis of errors and countermeasures.

Achieving validity in a software artifact depends critically on the ability of developers to understand the intentions of stakeholders. Miscommunication of domain-specific concepts can result in severe consequences, especially for safety-critical systems. Many development processes thus advocate the presence of a glossary to record the meanings of project-critical terms. However, limited guidance exists for the construction of good definitions that adequately communicate what particular domain-specific words and phrases mean. In this work, we offer a taxonomy of weaknesses in definitions, and propose a method for constructing better ones. We then analyze concepts specific to the domain of left ventricular assist devices (LVADs), a type of heart pump. We compare publicly available definitions to those we have constructed with our method, with respect to the weaknesses outlined. It is shown that our method produces higher-quality definitions more likely to allow correct interpretation by developers not expert in cardiac therapy terminology. 1.

Availability is a system performance parameter which provides insight into the probability that an item or system will be available to be committed to a specified requirement. Depending on the application, availability can be defined to include reliability, maintainability and logistic support information. For fleet management purposes, the ability to quantify availability in terms of all of its contributing elements is essential. This paper provides a discussion on a steady state operational availability model which can be used to assist the Canadian Air Force in its aircraft fleet management requirements. The availability model embodies scheduled and unscheduled maintenance and allows for impact analysis using in-service maintenance data. The model is sensitive to fleet size, aircraft flying rate, frequency of downing events, aircraft maintainability, scheduled inspection frequency, and scheduled inspection duration. The predictive capability of this availability model is currently providing the Canadian Air Force with a more sophisticated maintenance analysis decision support capability. In order for this paper to be available for general distribution, it must be unclassified. As a result, the case studies presented do not reveal the actual operational availability of any Canadian Air Force fleet. However, the level of detail provided is more than adequate to illustrate the case studies and give insight into