A combinatorial characterization of parabolic quadrics
Mauro Zannetti · Journal of Discrete Mathematical Sciences and Cryptography · 2009
In this paper we prove that, in PG(3, q), q odd, a (q 2 + q +1)-set of type ((n − 1)q + 1, nq + 1, (n + 1)q + 1)2, 1 ≤ n ≤ q, and type (a, b, c, d)1, with , such that any external line is contained in exactly one ((n − 1)q + 1)-secant plane is a parabolic quadric.