Computer Science Logic : 13th International Workshop CSL’99 8th Annual Conference of the EACSL Madrid Spain September 20–25 1999 Proceedings This book constitutes the refereed proceedings of the 13th Annual International Conference on Computer Science Logic CSL 99 held under the sponsorship of EACSL in Madrid Spain in September 1999. The 34 revised full papers presented together with five invited contributions were carefully reviewed and sleected from a total of 91 submissions. The papers are organized in sections on descriptive complexity; verification; temporal logic; lambda calculus and linear logic; logic programming modal logic and description logic; logic and complexity; lambda calculus and type theory; linear logic mu calculus and concurrency; and specification and data refinement