Moufang Polygons

Spherical buildings are certain combinatorial simplicial complexes intro­ duced, at first in the language of "incidence geometries," to provide a sys­ tematic geometric interpretation of the exceptional complex Lie groups. (The definition of a building in terms of chamber systems and definitions of the various related notions used in this introduction such as "thick," "residue," "rank," "spherical," etc. are given in Chapter 39. ) Via the notion of a BN-pair, the theory turned out to apply to si