  We show that the automorphisms of the flag space associated with a
3-dimensional projective space can be characterized as bijections preserving a
certain binary relation on the set of flags in both directions. From this we
derive that there are no other automorphisms of the flag space than those
coming from collineations and dualities of the underlying projective space.
Further, for a commutative ground field, we discuss the corresponding flag
variety and characterize its group of automorphic collineations.

Algebraic Geometry;Representation Theory