From July 25-August 6, 1966 a Summer School on Local Fields was held in Driebergen (the Netherlands), organized by the Netherlands Universities Foundation for International Cooperation (NUFFIC) with financial support from NATO. The scientific organizing Committl!e consisted ofF. VANDER BLIJ, A. H. M. LEVELT, A. F. MaNNA, J. P. MuRRE and T. A. SPRINGER. The Summer School was attended by approximately 80 mathematicians from various countries. The contributions collected in the present book are all based on the talks given at the Summer School. It is hoped that the book will serve the same purpose as the Summer School: to provide an introduction to current research in Local Fields and related topics. July 1967 T. A. SPRINGER Contents ARnN, M. and B. MAZUR: Homotopy of Varieties in the Etale Topology 1 BAss, H: The Congruence Subgroup Problem 16 BRUHAT, F. et J. TITs: Groupes algebriques simples sur un corps local . 23 CASSELS, J. W. S. : Elliptic Curves over Local Fields 37 DwoRK, B. : On the Rationality of Zeta Functions and L-Series 40 MaNNA, A. F. : Linear Topological Spaces over Non-Archimedean Valued Fields . 56 NERON, A. : Modeles minimaux des espaces principaux homo genes sur les courbes elliptiques 66 RAYNAUD, M. : Passage au quotient par une relation d'equivalence plate . 78 REMMERT, R. : Algebraische Aspekte in der nichtarchimedischen Analysis . 86 SERRE, J. -P. : Sur les groupes de Galois attaches aux groupes p-divisibles . 118 SWINNERTON-DYER, P. : The Conjectures of Birch and Swinnerton- Dyer, and of Tate . 132 TATE, J. T.