Software Library for Teaching Applications of Binary Decision Diagrams in Reliability Analysis

Reliability belongs to key characteristics of most technical, as well as, non-technical systems. Therefore, its evaluation should be one of the principal skills of graduates of technically oriented study programs, such as mechanical engineering, electrical engineering, computer engineering, or informatics. However, analysis of system reliability is a challenging task, especially in case of systems composed of many components. Main issues in this case are efficient representation of the system and fast computation of basic reliability characteristics, such as availability of the system or importance of the system components. The first issue can be solved by using special data structures and the second one by implementation of existing algorithms using these data structures. A Binary Decision Diagram (BDD) is one of the most prospective data structures that can be used for this purpose. It is a graph structure that allows representing Boolean functions in an efficient way. In reliability analysis, it can be used to represent structure of the system. However, manipulation with bigger BDDs and their application in computation of basic reliability indices usually requires good computer support in a form of specific software tool. The core of such a software tool should be a software library implementing operations that allows fast manipulation with BDDs. In this paper, we present one such library. The library is primarily intended for the development of software tools for reliability analysis of complex systems based on BDDs, and it will also be used as a support tool within practical classes of a course on reliability engineering that is taught at the Faculty of Management Science and Informatics of University of Zilina.