Cluster algebra structures and semicanonical bases for unipotent groups

By C. Geiss, Bernard Leclerc, J. Schröer. 2007

98 citations recorded by the source corpus.

Let Q be a finite quiver without oriented cycles, and let $\Lambda$ be the associated preprojective algebra. To each terminal representation M of Q (these are certain preinjective representations), we attach a natural subcategory $C_M$ of $mod(\Lambda)$. We show that $C_M$ is a Frobenius category,and that its stable category is a Calabi-Yau category of dimension 2. Then we develop a theory of mutations of maximal rigid objects of $C_M$, analogous to the mutations of clusters in Fomin and Zelevinsky's theory of cluster algebras. We show that $C_M$ yields a categorification of a cluster algebra $A(C_M)$, which is not acyclic in general. We give a realization of $A(C_M)$ as a subalgebra of the graded dual of the enveloping algebra $U(\n)$, where $\n$ is a maximal nilpotent subalgebra of the symmetric Kac-Moody Lie algebra $\g$ associated to the quiver Q. Let $S^*$ be the dual of Lusztig's semicanonical basis $S$ of $U(\n)$. We show that all cluster monomials of $A(C_M)$ belong to $S^*$, and that $S^* \cap A(C_M)$ is a basis of $A(C_M)$. Next, we prove that $A(C_M)$ is naturally isomorphic to the coordinate ring of the finite-dimensional unipotent subgroup $N(w)$ of the Kac-Moody group $G$ attached to $\g$. Here w = w(M) is the adaptable element of the Weyl group of $\g$ which we associate to each terminal representation M of Q. Moreover, we show that the cluster algebra obtained from $A(C_M)$ by formally inverting the generators of the coefficient ring is isomorphic to the coordinate ring of the unipotent cell $N^w := N \cap (B_-wB_-)$ of G. We obtain a corresponding dual semicanonical basis of this coorindate ring.

Subfields: Algebra and Number Theory, Geometry and Topology, Mathematical Physics

View Paper: https://www.semanticscholar.org/paper/ac114da69e88e96d5993e1e74ed27472903832c5

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In Algebra and Number Theory

  1. B. Keller
  2. Osamu Iyama
  3. I. Reiten
  4. Bernard Leclerc
  5. C. Geiss
  6. J. Schröer
  7. K. Yamagata
  8. Andrzej Skowronski

In Geometry and Topology

  1. B. Keller
  2. Osamu Iyama
  3. Bernard Leclerc
  4. I. Reiten
  5. C. Geiss
  6. J. Schröer
  7. K. Yamagata
  8. Andrzej Skowronski

In Mathematical Physics

  1. Osamu Iyama
  2. B. Keller
  3. Bernard Leclerc
  4. I. Reiten
  5. C. Geiss
  6. J. Schröer
  7. Philipp Lampe
  8. Aslak Bakke Buan

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