Geometries, the principle of duality, and algebraic groups

Jacques Tits gave a general recipe for producing an abstract geometry from a semisimple algebraic group. This expository paper describes a uniform method for giving a concrete realization of Tits's geometry and works through several examples. We also give a criterion for recognizing the automorphism of the geometry induced by an automorphism of the group. The E6 geometry is studied in depth.

(This paper has appeared in Expositiones Mathematicae, vol. 24, No. 3 (2006) 195-234)


M. Carr < mpcarr@umich.edu >

S. Garibaldi < skip@member.ams.org >