%0 Journal Article %T Sequences of reflection functors and the preprojective component of a valued quiver %A Mark Kleiner %A Helene R. Tyler %J Mathematics %D 2006 %I arXiv %X This paper concerns preprojective representations of a finite connected valued quiver without oriented cycles. For each such representation, an explicit formula in terms of the geometry of the quiver gives a unique, up to a certain equivalence, shortest (+)-admissible sequence such that the corresponding composition of reflection functors annihilates the representation. The set of equivalence classes of the above sequences is a partially ordered set that contains a great deal of information about the preprojective component of the Auslander-Reiten quiver. The results apply to the study of reduced words in the Weyl group associated to an indecomposable symmetrizable generalized Cartan matrix. %U http://arxiv.org/abs/math/0608175v1