In this paper,we study the exact boundary and observability of the wave equation with some of the variables are discreted.It mainly studies the following two kinds of cir-cumstances. The first case is the equation with λ≤λ*, λ*=(N-2)/4and the time discretization.Then we study the equation Wether the total energy of solutions can be estimated uniformly in terms of the energy concentrated on the boundary as the net-spacing hâ†'0.In this article the introduction describes the problem where it came from, equation of time discretization, two or three chapter of well-posedness, observability and control-lability, in the fifth chapter, study on the one-dimensional case observability. |