Copyright © The Author 2007. Published by Oxford University Press.
Admissible Sequences, Preprojective Representations of Quivers, and Reduced Words in the Weyl Group of a Kac-Moody Algebra
Department of Mathematics, Syracuse University, Syracuse, 13244-1150, Newyork
Correspondence: Correspondence to be sent to: Mark Kleiner, Department of Mathematics, Syracuse University, Syracuse, 13244-1150, New York. e-mail: mkleiner{at}syr.edu
This article studies connections between the preprojective representations of a finite connected valued quiver without oriented cycles, the (+)-admissible sequences of vertices, and the Weyl group. For each preprojective representation, a shortest (+)-admissible sequence annihilating the representation is unique up to a certain equivalence. A (+)-admissible sequence is the shortest sequence annihilating some preprojective representation if and only if the product of simple reflections associated to the vertices of the sequence is a reduced word in the Weyl group. These statements have the following application that strengthens known results of Howlett and FominZelevinsky. For any fixed Coxeter element of the Weyl group associated to an indecomposable symmetrizable generalized Cartan matrix, the group is infinite if and only if the powers of the element are reduced words.
Dedicated to the memory of Andrei Vladimirovich Roiter
Communicated by Toshiyuki Kobayashi
References
- Bernstein I. N., Gelfand I. M., Ponomarev V. A. Coxeter Functors and Gabriel's Theorem. Uspekhi Matematicheskikh Nauk (1973) 28:1933. Transl. Russ. Math. Serv. 28 (1973): 17-32.
- Auslander M., Reiten I., Smalø S. O. Representation Theory of Artin Algebras (1994) vol. 36. New York: Cambridge University Press. Cambridge Studies in Advanced Mathematics.
- Kleiner M., Tyler H. R. Admissible Sequences and the Preprojective Component of a Quiver. Advances in Mathematics (2005) 192(no. 2):376402.[CrossRef][Web of Science]
- Bourbaki N. Elements of Mathematics (Berlin) (2002) Berlin: Springer-Verlag. 1300. Lie Groups and Lie Algebras. Chapters 4-6 translated from the 1968 French original by Andrew Pressley.
- Kac V. G. Infinite-Dimensional Lie Algebras (1990) 3rd ed. Cambridge: Cambridge University Press.
- Howlett R. B. Coxeter Groups and M-Matrices. Bulletin of the London Mathematical Society (1982) 14(no. 2):137141.
[Free Full Text] - Fomin S., Zelevinsky A. Cluster Algebras IV: Coefficients. Compositio Mathematica (2007) 143(no. 1):112164.[CrossRef][Web of Science]
- Dlab V., Ringel C. M. Indecomposable Representations of Graphs and Algebras. Memoirs of the American Mathematical Society (1976) 6(no. 173):157.
- Kleiner M., Tyler H. R. Sequences of Reflection Functors and the Preprojective Component of a Valued Quiver. (2006) Preprint arXiv:math.RT/0608175.
- Krammer D. The Conjugacy Problem of Coxeter Groups. (1994) Ph. D. Thesis, Universiteit Utrecht, Available at "http://www.maths.warwick.ac.uk/
daan/. - Speyer D. E. Reduced Powers of Coxeter Elements. unpublished manuscript.
- Reading N. Clusters, Coxeter-Sortable Elements and Noncrossing Partitions. Transactions of the American Mathematical Society (2005) Preprint arXiv:math.CO/0507186.
- Fomin S., Zelevinsky A. Y-Systems and Generalized Associahedra. Annals of Mathematics (2) (2003) 158(no. 3):9771018.[Web of Science]
- Marsh R., Reineke M., Zelevinsky A. Generalized Associahedra via Quiver Representations. Transactions of the American Mathematical Society (2003) 355(no. 10):41714186.[CrossRef][Web of Science]
- McCammond J. Noncrossing Partitions in Surprising Locations. American Mathematical Monthly (2006) 113:598610.[Web of Science]
- Ringel C. M. Tame Algebras and Integral Quadratic Forms (1984) vol. 1099. Berlin: Springer-Verlag. Lecture Notes in Mathematics.
- Dlab V., Ringel C. M. On Algebras of Finite Representation Type. Journal of Algebra (1975) 33:306394.[CrossRef][Web of Science]
- Ringel C. M. Greens theorem on Hall Algebras, Representation Theory of Algebras and Related Topics (Mexico City, 1994). In: CMS Conference Proceedings (1996) vol. 19. Providence, RI: American Mathematical Society. 185245.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||