Inhaltsangabe1. Introduction to Linear Elliptic Problems.- 1.1. The Lax-Milgram theorem.- 1.2. Elementary notions on Sobolev spaces.- 1.3. Applications to linear elliptic problems.- 2. Some Model Techniques.- 2.1. The case of lateral Dirichlet boundary conditions on a rectangle.- 2.2. The case of lateral Neumann boundary conditions on a rectangle.- 2.3. The case of lateral Dirichlet boundary conditions revisited.- 2.4. A different point of view.- Open problems.- 3. A General Asymptotic Theory for Linear Elliptic Problems.- 3.1. A general convergence result in H1 (S24,).- 3.2. A sharper rate of convergence.- 3.3. Convergence in higher Sobolev spaces.- Open problems.- 4. Nonlinear Elliptic Problems.- 4.1. Variational inequalities.- 4.2. Quasilinear elliptic problems.- 4.3. Strongly nonlinear problems.- Open problems.- 5. Asymptotic Behaviour of some Nonlinear Elliptic Problems.- 5.1. The case of variational inequalities.- 5.2. The case of quasilinear problems.- Open problems.- 6. Elliptic Systems.- 6.1. Some inequalities.- 6.2. Existence results for linear elliptic systems.- 6.3. Nonlinear elliptic systems.- Open problems.- 7. Asymptotic Behaviour of Elliptic Systems.- 7.1. The case of linear elliptic systems satisfying the Legendre condition.- 7.2. The system of elasticity.- Open problems.- 8. Parabolic Equations.- 8.1. Functional spaces for parabolic problems.- 8.2. Linear parabolic problems.- 8.3. Nonlinear parabolic problems.- 9. Asymptotic Behaviour of Parabolic Problems.- 9.1. The linear case.- 9.2. A nonlinear case.- Open problems.- Concluding Remark.