Abstract

Cluster automorphisms have been shown to have links to the mapping class groups of surfaces, maximal green sequences and to exchange graph automorphisms for skew-symmetric cluster algebras. In this paper we generalise these results to the skew-symmetrizable case by introducing a marking on the exchange graph. Many skew-symmetrizable matrices unfold to skew-symmetric matrices and we consider how cluster automorphisms behave under this unfolding with applications to coverings of orbifolds by surfaces.

Highlights

  • Cluster algebras were introduced by Fomin and Zelevinsky in [14], and have since found applications across many types of mathematics

  • Cluster algebras were shown to be closely related to triangulations of surfaces by Fomin, Shapiro and Thurston in [13], where a quiver is constructed from a given triangulation and quiver mutations correspond to flipping an edge in the triangulation

  • A skew-symmetrizable matrix associated to a good orbifold with order 2 orbifold points can be unfolded to a skew-symmetric matrix associated to a surface which covers the orbifold. In this case we show that automorphisms of the marked exchange graph induce automorphisms of the unfolded exchange graph

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Summary

Introduction

Cluster algebras were introduced by Fomin and Zelevinsky in [14], and have since found applications across many types of mathematics. In the same paper Fomin and Zelevinsky defined the exchange graph of a cluster algebra to better visualise the combinatorics of the mutation class These graphs proved a useful tool in their classification of finite-type cluster algebras in [15] where these algebras were shown to correspond to Dynkin diagrams. The cluster automorphisms of any cluster algebra generated by mutationfinite skew-symmetrizable matrices can be studied using just the combinatorial properties of its marked exchange graph. We finish the paper with a conjecture generalising a result of Brustle and Qiu linking the tagged mapping class group of a surface with the cluster automorphisms of the corresponding surface cluster algebra.

Mutations
Exchange graphs
Cluster automorphisms
Examples
Generalising automorphisms to skew-symmetrizable case
Marked exchange graph
Geodesic loops
Exchange graph automorphism effects on diagrams and matrices
Unfoldings
Mapping class groups
Unfoldings and covering maps
Full Text
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