AbstractÐThis paper examines and proposes an approach to writing software specifications, based on research in systems theory, cognitive psychology, and human-machine interaction. The goal is to provide specifications that support human problem solving and the tasks that humans must perform in software development and evolution. A type of specification, called intent specifications, is constructed upon this underlying foundation. Index TermsÐRequirements, requirements specification, safety-critical software, software evolution, human-centered specifications, means-ends hierarchy, cognitive engineering.

A limiting factor in the industrial acceptance of formal specifications is their readability, particularly for large, complex engineering systems. We hypothesize that multiple visualizations generated from a common model will improve the requirements creation, reviewing and understanding process. Visual representations, when effective, provide cognitive support by highlighting the most relevant interactions and aspects of a specification for a particular use. In this paper, we propose a taxonomy and some preliminary principles for designing visual representations of formal specifications. The taxonomy and principles are illustrated by sample visualizations we created while trying to understand a formal specification of the MD-11 Flight Management System.

Abstract. ProB is an animator and model checker for the B method. It also allows to visualise the state space of a B machine in graphical way. This is often very useful and allows users to quickly spot whether the machine behaves as expected. However, for larger state spaces the visualisation quickly becomes difficult to grasp by users (and the computation of the graph layout takes considerable time). In this paper we present two relatively simple algorithms to often considerably reduce the complexity of the graphs, while still keeping relevant information. This makes it possible to visualise much larger state spaces and gives the user immediate feedback about the overall behaviour of a machine. The algorithms have been implemented within the ProB toolset and we highlight their potential on several examples. We also conduct a thorough experimentation of the algorithm on 47 B machines and analyse the results.