... Proof Recall first that every root is either a positive sum of simple roots or a negativesum and not both since they re linearly independent If fi 2 Delta is not ff then it is not a multiple of ff and therefore contains some othersimple root with a positive coefficient When we reflect using rff it doesn...
.ps...://math.berkeley.edu/~allenk/courses/spr02/261b/notes/Weylchambers5.ps
