We consider the unitary group U of complex, separable, infinitedimensional Hilbert space as a discrete group. It is proved that, wheneverUacts by isometries on a metric space, every orbit is bounded. Equivalently, U is not the union of a countable chain of proper subgroups, and whenever E U generates U, it does so by words of a fixed finite length.
© 2001-2024 Fundación Dialnet · Todos los derechos reservados