Abstract:
It is proved that there exists a bounded holomorphic operator-function $z\mapsto F(z)$, $|z|<1$, with compact values (in a separable Hilbert space) and such that its boundary values $F(\zeta)$, $|\zeta|=1$, are compact on one (given) arc of the circle and not compact on the other. The corresponding example is constructed with the help of vectorial Hankel operators.