5 Assessing the Constrained Expression Toolset

constrained expression analysis of real-time software." Submitted for publication. Available as Toward broad applicability of analysis methods for distributed software systems ," ACM Trans. 37 our experiments. This research involves improvements in the toolset to enhance its performance and make it easier and more convenient to use, and extensions to the constrained expression formalism and the analysis techniques automated by the toolset to expand the range of questions it can answer and concurrent systems it can analyze. We are working on improvements or extensions to every component of the toolset. Many of these modiications are aimed at more fully automating the analysis of systems with large numbers of identical tasks described previously. Others are intended to improve the inequality solving component of the toolset, rst by improving the heuristics used in our current version of IMINOS and later by replacing IMINOS with a special-purpose integer linear programming system that can exploit the special structure found in the inequality systems that our tools generate. Still others will make the behavior generator more eecient and more helpful in cases where IMINOS nds spurious solutions. Our work on extending the constrained expression formalism and analysis techniques will allow the toolset to be used with a wider range of problems and queries. Among the topics we are investigating are methods for directly handling more complex queries, such as \Can event a occur between events b and c?", ways to express innnite behaviors so that questions of fairness and starvation can be addressed, and ways to modularize the constrained expression representations of systems and their analysis. We have also recently developed and begun experimenting with an extension of the constrained expression analysis techniques that can be used to assess the timing properties of concurrent systems, and have extended the toolset to implement this technique. Details of this approach to constrained expression analysis of real-time systems and an example of its application can be found in 23]. Based on the results of the experiments conducted with the current version of the toolset and the improvements to be expected in the near future, we believe that the constrained expression approach can serve as a foundation for practical tools for developers of concurrent software. 36 inequalities that do not correspond to traces of CEDL systems. The approach of 26] is to use the T-invariants rst to detect and remove certain \inconsis-tency" deadlocks, and then to guide the construction …