Table of contents : Introduction to the theory of complexity and approximation algorithms....Pages 5-28 Introduction to randomized algorithms....Pages 29-39 Derandomization....Pages 41-61 Proof checking and non-approximability....Pages 63-82 Proving the PCP-Theorem....Pages 83-160 Parallel repetition of MIP(2,1) systems....Pages 161-177 Bounds for approximating MaxLinEq3-2 and MaxEkSat....Pages 179-211 Deriving non-approximability results by reductions....Pages 213-233 Optimal non-approximability of MaxClique....Pages 235-248 The hardness of approximating set cover....Pages 249-262 Semidefinite programming and its applications to approximation algorithms....Pages 263-298 Dense instances of hard optimization problems....Pages 299-311 Polynomial time approximation schemes for geometric optimization problems in euclidean metric spaces....Pages 313-323