finite classical polar spaces can be summarised by the following table, where is the dimension of the underlying projective space and is the rank of the polar space. The number of points in a is denoted by and it is equal to . When is equal to , we get a generalized quadrangle. Classification Jacques Tits proved that a finite polar space of rank at least three, is always isomorphic with one of the three types of classical polar spaces given above. This leaves open only the problem of classifying the finite generalized quadrangles. References . Families of sets Projective geometry