Notes on elation generalized quadrangles

Let S be a finite generalized quadrangle of order (s, t), s, t > 1. An "elation about a point p" of S is an automorphism fixing p linewise and fixing no point which is not collinear with p. An elation that generates a cyclic group of elations is called a "standard elation". One of the problems already considered in Payne and Thas (Finite Generalized Quadrangles (1984)) is to determine just when the set of elations about the point (infinity) is a group. The purpose of this paper is to provide an example where this is not the case, and then to show that for a flock generalized quadrangle the usual group of elations about (infinity) is the complete set of standard elations about (infinity). (C) 2003 Elsevier Ltd. All rights reserved.