Introductory paper: Scalability aspects of validation

This special section is devoted to a selection of papers that appeared originally in the Proceedings of TACAS 2001, the 7th International Conference on Tools and Algorithms for the Construction and Analysis of Systems [1] which took place in Genova, Italy in April 2001 as a constituent event of the European joint conferences on theory and Practice of Software. All papers present approaches, tools and algorithms that aim at extending the scope of formal techniques (coverage of systems specifications, data structures, size, and their trade-offs) for validation, verification, and testing of software systems. They are by no means a complete account of the numerous ways in which real software and software systems may become subject to rigorous investigation, but they provide an interesting sampling of novel approaches towards scalability of formal methods-based validation.