Buildings
Alexandre V Borovik, Israel M. Gelfand, Neil L. White · Birkhäuser Boston eBooks · 2003
We begin this chapter with a return to basics and look at the underlying combinatorics of the Gaussian elimination procedure. This classical routine involves permutation of rows and columns of a matrix. The rules these permutations obey are extremely simple; when axiomatized in group-theoretic terms, they become what are known as axioms for a BN -pair (or a Tits system ) and very quickly lead to Coxeter groups appearing on the scene.