Oriented Rank Three Matroids and Projective Planes

Oriented Rank Three Matroids and Projective Planes

Quite recently, GOODMAN, POLLACK, WENGER and ZAMFIRESCU [7], [8] have proven two conjectures by GRÜNBAUM right, showing that any arrangement of pseudolines in the plane can be embedded into a flat projective plane and that there exists a universal topological projective plane in which every arrangement of pseudolines is stretchable. By FOLKMAN and LAWRENCE's theorem [6], this plane contains eve...

Transitive projective planes and 2-rank

Suppose that a group G acts transitively on the points of a nonDesarguesian plane, P. We prove first that the Sylow 2-subgroups of G are cyclic or generalized quaternion. We also prove that P must admit an odd order automorphism group which acts transitively on the set of points of P. 1 MSC(2000): 20B25, 51A35.

Rank-Three Matroids are Rayleigh

A Rayleigh matroid is one which satisfies a set of inequalities analogous to the Rayleigh monotonicity property of linear resistive electrical networks. We show that every matroid of rank three satisfies these inequalities.

Area-minimizing Projective Planes in Three-manifolds

Affine and projective planes