We define, for the trace of solution of vibrating plates equation, norms with initial conditions in no regular spaces. Then, we give the corresponding exact controllability results.

Siano $A$, $B$ sottoinsiemi convessi, chiusi e limitati di uno spazio normato $X$, con le frontiere $frA$, $frB$. Dimostriamo che $h(A,B)=h(frA,frB)$, dove $h$ è la metrica di Hausdorff tra sottoinsiemi chiusi di $X$. Studiamo inoltre la continuità e la semicontinuità superiore ed inferiore di una multifunzione di tipo «frontiera».

We analyze the problem of switching controls for control systems endowed with different actuators. The goal is to control the dynamics of the system by switching from an actuator to the other in a systematic way so that, in each instant of time, only one actuator is active. We first address a finite-dimensional model and show that, under suitable rank conditions, switching control strategies exist and can be built in a systematic way. To do this we introduce a new variational principle building...