Non-smooth unobservable states in control problem for the wave equation in ${\mathbb{R}}^3$ (corrected)

M. I. Belishev, A. F. Vakulenko

The paper deals with a dynamical system \begin{align*} &u_{tt}-Δu=0, \qquad (x,t) \in {\mathbb R}^3 \times (-\infty,0) \\ &u \mid_{|x|<-t} =0 , \qquad t<0\\ &\lim_{s \to \infty} su…