Preface by the section editor

Abstract.

Preliminary versions of the papers of this special section originally appeared in the proceedings of the 6th edition of the conference “Tools and Algorithms for the Construction and Analysis of Systems” (Tacas) held in Berlin early April 2000 as a constituent event of the European joint conferences on Theory and Practice of Software. All papers present tools relevant in the context of systems validation. The first three focus on extensions or particular applications of model-checking techniques, whereas the fourth is about integration of design tools with validation tools, in particular theorem provers and model-checkers.