Baer subset of projective plane

Definition
A closed subset of a projective plane is termed a Baer subset if it satisfies the following two additional conditions:


 * Every point in the projective plane is incident with a line in the closed subset
 * Every line in the projcetive plane is incident with a point in the closed subset

Stronger properties

 * Baer subplane of projective plane
 * Maximal nonplanar closed subset of projective plane

Weaker properties

 * Maximal closed subset of projective plane
 * Closed subset of projective plane