Variational formulation and piece-wise linear finite element approximations
of Poisson's problem. Dirichlet and Neumann boundary conditions and
Poincaré's and Friedrichs's inequalities. A word about linear elasticity.
Condition numbers of finite element matrices and the preconditioned conjugate
Domains and subdomains. Subdomain matrices as building blocks for domain
decomposition methods and the related Schur complements. The two-subdomain