Buildings governed by twisted Bruhat orders

Abstract

This paper introduces the notion of a twisted building associated to a Coxeter system and an initial section of a reflection order. These are pairs of buildings and a map between them which depends on a twisted Bruhat order. It is proved that projection maps exist between components and that the common apartment property holds for a suitable notion of an apartment, generalising what is known for twin buildings. Several well-known examples are given, including a family of twisted buildings associated to an affine building and its façades.