1.1 Projective spaces and spreads. A projective space is a geometry consisting of a set of points and a set of lines, where each line is a subset of the point set, such that the following axioms hold: • Any two points are on exactly one line. • Let A, B, C, D be four distinct points no three of which are collinear. If the lines AB and CD intersect each other, then the lines AD and BC also inter...