STOC SPAA ICALP 2001: Christos H. Papadimitriou: Algorithms, games, and the internet. Boris A. Trakhtenbrot: Automata, circuits and hybrids: facets of continuous time. Ahmed Bouajjani: Languages, Rewriting Systems, and Verification of Infinite-State Systems. Martin Große-Rhode: Integrating Semantics for Object-Oriented System Models. Mogens Nielsen: Modelling with Partial Orders - Why and Why Not? Ingo Wegener: Theoretical Aspects of Evolutionary Algorithms. Uriel Feige: Reflections on the PCP theorem and its consequences. (Godel Award Lecture) Andrew C. C. Yao: Some Perspectives on Computational Complexity. (Turing Award Lecture)