COVERS OF GENERALIZED QUADRANGLES

Characterizations of Generalized Quadrangles by Generalized Homologies

Let S= (P, B, I) be a generalized quadrangle of order (s, t). For X, y E P, X+ y. let X(x, y) be the group of all collineations of S fixing x and y linewise. If ZE (4 YJL> then the set of all points incident with the line xz (resp. y;) is denoted by z(resp. 3. The generalized quadrangle S = (P, B, I) is said to be (x, y)-transitive, x+ y, if X(x, y) is transitive on each set Z{x, z} and jZ’-{ y...

Finite Generalized Quadrangles

Foundations of elation generalized quadrangles

In these notes we are interested in the following fundamental question: “Given a thick generalized quadrangle S(x) with elation point (respectively center of transitivity) x , when does the set of all elations about x form a group?”. It was the general belief for a long time that this is usually the case. However, the goal of these notes is to show that this belief is wrong. To that end, we wil...

Authentication codes from generalized quadrangles

Authentication codes were introduced by Simmons in [3]. Many combinatorial structures can be used to construct authentication codes, and interesting combinatorial bounds can be obtained, see e.g. [7], [8] and [9]. We investigate authentication codes arising from generalized quadrangles (GQs), which was first done in [1]. The use of intricated techniques and constructions from the theory of GQs ...

Probabilistic constructions in generalized quadrangles

We study random constructions in incidence structures, and illustrate our techniques by means of a well-studied example from finite geometry. A maximal partial ovoid of a generalized quadrangle is a maximal set of points no two of which are collinear. The problem of determining the smallest size of a maximal partial ovoid in quadrangles has been extensively studied in the literature. In general...