  The anharmonic vibrator and rotor regions in nuclei are investigated in the
framework of the interacting boson model using an ensemble of random one- and
two-body interactions. We find a predominance of L(P)=0(+) ground states, as
well as strong evidence for the occurrence of both vibrational and rotational
band structures. This remarkable result suggests that such band structures
represent a far more general (robust) property of the collective model space
than is generally thought.
