This book constitutes the refereed proceedings of the 9th International Conference on Theoretical Computer Science, ICTCS 2005, held at the Certosa di Pontignano, Siena, Italy, in October 2005.
The 29 revised full papers presented together with an invited paper and abstracts of 2 invited talks were carefully reviewed and selected from 83 submissions. The papers address all current issues in theoretical computer science and focus especially on analysis and design of algorithms, computability, computational complexity, cryptography, formal languages and automata, foundations of programming languages and program analysis, natural computing paradigms (quantum computing, bioinformatics), program specification and verification, term rewriting, theory of logical design and layout, type theory, security, and symbolic and algebraic computation.