COSMOLOGICAL MODELS Cargèse Lectures 1998 -- 1 Basic relations -- 2 1 + 3 covariant description and equations -- 3 Tetrad description -- 4 FLRW universes and observational relations -- 5 Solutions with symmetries -- 6 Bianchi universes (s = 3) -- 7 Almost-FLRW universes -- 8 CBR anisotropies -- 9 Conclusion and open issues -- Topology of the Universe: Theory and Observation -- 1 Introduction -- 2 A Brief History of Cosmological Topology -- 3 Mathematical background -- 4 Topology and Cosmology -- 5 Observational methods, candidates and constraints -- 6 Conclusion -- Symmetries in General Relativity and Beyond -- 1 Introduction -- 2 Spaces and manifolds -- 3 Connections on a manifold -- 4 Relativity and the Poincaré group -- 5 Extending -- 6 Conclusion -- Gravitational Lenses -- 1 Introduction -- 2 Physical mechanisms -- 3 The case of a point-like mass distribution -- 4 Gravitational lenses in Cosmology -- 5 Galaxy clusters as gravitational lenses -- 6 The weak lensing regime -- 7 The weak lensing as a probe of the Large-Scale Structures -- Cosmological Applications of Gravitational Lensing -- 1 Introduction -- 2 Some important quantities and properties -- 3 Academic examples -- 4 Astrophysical examples -- 5 Conclusion and future prospects -- Measurement of Cosmological Parameters Using Type Ia Supernovae -- 1 Which cosmological parameters - How ? -- 2 Type Ia SNe are excellent cosmological tools -- 3 Detection/Follow-up of distant SNe -- 4 Recent results on Ho, QM and QA from SNe Ia -- 5 The (near) future -- Primordial Nucleosynthesis -- 1 Introduction -- 2 Theory -- 3 Abundances -- 4 Chemical evolution -- 5 Likelihood analysis -- 6 Constraints from BBN -- 7 Summary -- Searches For Dark Matter -- 1 Introduction -- 2 Wimps -- 3 Axions -- 4 Neutrinos -- 5 Machos -- Temperature Anisotropies of the Cosmic Microwave Background -- 1 Introduction -- 2 Temperature fluctuations of the CAM -- 3 Angular power spectrum of the primary anisotropies -- 4 The Sunyaev-Zel'dovich effect -- 5 In homogeneous re-ionisation -- Primordial Galaxies: From Local Hii Galaxies to High Redshift Galaxies -- 1 Introduction -- 2 The HII galaxies -- 3 The early IUE observations and interpretations -- 4 HST observations -- 5 The role of the velocity structure of the ISM -- 6 The evolution of superbubbles in extended HI halos -- 7 Discussion -- Active Galactic Nuclei -- 1 Short Historic, Basic Properties -- 2 Physical Properties -- 3 Statistics -- 4 AGN and Cosmology -- 5 Prospects -- 6 Bibliography -- Cosmic Velocity Fields -- 1 Introduction -- 2 Friedmann models and horizons -- 3 The Sunyaev-Zeldovich effect -- 4 Statistics and Fourier analysis -- 5 Newtonian fluid equations -- 6 Method and data -- 7 Reconstruction of velocity fields.