Miklós Ajtai Worst-Case Complexity, Average-Case Complexity and Lattice Problems Doc.Math.J.DMV Extra Volume ICM III (1998) 421-428 Abstract 2 k, dvi.gz 16 k, dvi 37 k, ps.gz 57 k. Joan Feigenbaum Games, Complexity Classes, and Approximation Algorithms Doc.Math.J.DMV Extra Volume ICM III (1998) 429-439 Abstract 2 k, dvi.gz 21 k, dvi 49 k, ps.gz 61 k. Johan Håstad On Approximating NP-Hard Optimization Problems Doc.Math.J.DMV Extra Volume ICM III (1998) 441-450 Abstract 2 k, dvi.gz 21 k, dvi 47 k, ps.gz 75 k. Toniann Pitassi Unsolvable Systems of Equations and Proof Complexity Doc.Math.J.DMV Extra Volume ICM III (1998) 451-460 Abstract 2 k, dvi.gz 20 k, dvi 46 k, ps.gz 74 k. Madhu Sudan Probabilistic Verification of Proofs Doc.Math.J.DMV Extra Volume ICM III (1998) 461-470 Abstract 2 k, dvi.gz 23 k, dvi 52 k, ps.gz 79 k. Artur Andrzejak and Emo Welzl Halving Point Sets Doc.Math.J.DMV Extra Volume ICM III (1998) 471-478 Abstract 2 k, dvi.gz 16 k, dvi 34 k, ps.gz 65 k. This manuscript may contain graphics, therefore the dvi files may be incomplete.