We describe an approach to user interface design based on ideas from social science, narratology (the theory of stories), cognitive science, and a new area called algebraic semiotics. Social analysis helps to identify certain roles for users with their associated requirements, and suggests ways to make proofs more understandable, while algebraic semiotics, which combines semiotics with algebraic specification, provides rigorous theories for interface functionality and for a certain technical notion of quality. We apply these techniques to designing user interfaces for a distributed cooperative theorem proving system, whose main component is a website generation and proof assistance tool called Kumo. This interface integrates formal proving, proof browsing, animation, informal explanation, and online background tutorials, drawing on a richer than usual notion of proof. Experience with using the interface is reported, and some conclusions are drawn.

: We describe some tools to support distributed cooperative design and validation of software systems. Workers at different sites can collaborate on tasks including specification, refinement, validation, verification, and documentation. A distributed database supports alternative and incomplete activities, and can be read using any web browser; remote proof execution, animation, and informal explanation are supported, and results are broadcast by a protocol that prevents inconsistencies. The Kumo tool assists with validations and generates documentation websites. A range of formality is supported, from full mechanical proofs to informal "back of envelope" arguments, using a fuzzy logic for confidence levels. Some conclusions drawn from experiments are reported. 1 Introduction Software engineering is very difficult. Typical projects have multiple workers, often at multiple sites with different schedules; then it is difficult to share information and coordinate tasks; documentation may...