Computer Aided Verification : 12th International Conference CAV 2000 Chicago IL USA July 15 19 2000. Proceedings This book constitutes the refereed proceedings of the 12th International Conference on Computer Aided Verification CAV 2000 held in Chicago IL USA in July 2000.The 35 revised full papers presented together with 9 tool papers were carefully reviewed and selected from 91 submissions. The papers address all current aspects of the theory and practice of formal methods for hardware and software verification. Emphasis is given to verification algorithms methods and tools and their implementation