Finite affine planes in projective spaces

Finite linear spaces and projective planes

In 1948, De Bruijn and Erdös proved that a finite linear space on v points has at least v lines, with equality occurring if and only if the space is either a near-pencil (all points but one collinear) or a projective plane . In this paper, we study finite linear spaces which are not near-pencils . We obtain a lower bound for the number of lines (as a function of the number of points) for such l...

Affine and projective planes

Characterizations of Finite Projective and Affine Spaces

THEOREM 1. A finite incidence structure is isomorphic to the design of points and hyperplanes of a finite projective or affine space of dimension greater than or equal to 4 if and only if there are positive integers v, k, and y, with ju > 1 and (/A — l)(v — k) 7* (k — ju) such that the following assumptions hold. (I) Every block is on k points, and every two intersecting blocks are on p. common...

Berlekamp's Switching Game on Finite Projective and Affine Planes

We adapt Berlekamp’s light bulb switching game to finite projective plans and finite affine planes, then find the worst arrangement of lit bulbs for planes of even and odd orders. The results are then extended from the planes to spaces of higher dimension. 1 Berlekamp’s Switching Game The original game is simple enough. 100 light bulbs arranged in 10 rows and 10 columns. Each column and row has...

Affine Spaces within Projective Spaces

We endow the set of complements of a fixed subspace of a projective space with the structure of an affine space, and show that certain lines of such an affine space are affine reguli or cones over affine reguli. Moreover, we apply our concepts to the problem of describing dual spreads. We do not assume that the projective space is finitedimensional or pappian. Mathematics Subject Classification...