1. Dipartimento di Matematica e Geoscienze , Università di Trieste , Trieste , Italy brundu@units.it;3. Dipartimento di Matematica e Geoscienze , Università di Trieste , Trieste , Italy
Abstract:
We classify the singularities of a surface ruled by conics: they are rational double points of type An or Dn. This is proved by showing that they arise from a precise series of blow-ups of a suitable surface geometrically ruled by conics. We determine also the family of such surfaces which are birational models of a given surface ruled by conics and obtained in a “minimal way” from it.