BLT-sets : a model for flocks in odd characteristic
Maska Law (Università di Roma ``La Sapienza'')

In this talk we will discuss a model for flocks of the quadratic cone over fields of odd characteristic, provided by the notion of a BLT-set. A BLT-set is a set of q+1 points of the nonsingular parabolic quadric Q(4,q), q odd, such that the polar line of any triple of points of the set is exterior to the quadric. From any point of a BLT-set, one can construct a flock of the quadratic cone, and so BLT-sets provide a more general setting in which to study such flocks.