Tools for Distributed Cooperative Design and Validation

We describe some tools to support distributed cooperative design and validation of software systems. Workers at di erent sites can collaborate on tasks including speci cation, re nement, validation, veri cation, 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 con dence levels. Some conclusions drawn from experiments are reported.