On Attainable Set and Controllability for Abstract Control Problem with   Unbounded Input Operator
  For linear evolution control system described by $\dot{x}=Ax(t)+Bu(t),x(0)=x_{0}$ ($A$ generates a strongly continuous semigroup ${S(t)}_{t\ge 0}$ in a Banach space $X$; $B$ is a linear unbounded operator), the attainable set $K(t)$ is studied. Conditions of the independence of $t$ for its closure $\bar{K(t)}$ are established. Controllability conditions for some classes of evolution systems are obtained. 
B. Shklyar (Department of Science, Center for Technological Education,   Holon, Israel)