Ha Henny Wilbrink

Near polygons and Fischer spaces

In this paper we exploit the relations between near polygons with lines of size 3 and Fischer spaces to classify near hexagons with quads and with lines of size three. We also construct some infinite families of near polygons.

A note on planar difference sets

It is proven that if G is an abelian regular automorphism group of a projective plane of order n and if p is a prime dividing n exactly once, then a certain identity holds in the group algebra Fp|G|. As a corollary we obtain that n = p if p = 2 or 3.

Hermitian unitals are code words

We show that a unital PG(2, q2) is Hermitian if and only if it is in the code generated by the lines of PG(2, q2). This implies the truth of a conjecture made by Assmus and Key.

Alternative proof of Sine's theorem on the size of a regular polygon in R n with the e ∞ -metric

It is shown that a regular polygon inRn with the (2n)n-metric has at most (2n)n vertices.

Some 2–ranks

Abstract We compute the dimension of some of the binary codes associated with the unitial U (3, q ), the generalized quadrangle U (4, q ) and its dual O 6 − ( q ) for odd q .

A class of graphs containing the polar spaces

We consider finite graphs with the property that there exists a constant e such that for every maximal clique M and vertex x not in M, x is adjacent to exactly e vertices in M. It is shown that these graphs have a highly geometric structure which in many ways resembles that of the polar spaces.

Characterization of complete exterior sets of conics

AbstractLet ε be a set ofn

Blocking sets in translation planes

frac{{q + 1}}{2}