479 research outputs found
Friezes with coefficients
For a cluster algebra over of geometric type, we
define a of to be a -algebra
homomorphism from to that takes positive integer
values on all cluster variables and all frozen variables. We present some basic
facts on friezes, including frieze testing criteria, the notion of
when is finitely generated, and
pullbacks of friezes under certain -algebra homomorphisms. For
cluster algebras with acyclic seeds, we introduce and we give a sufficient condition for frieze patterns to be
equivalent to friezes. For the special cases when has an acyclic
seed with either trivial coefficients, principal coefficients, or what we call
the (named after A. Berenstein, S. Fomin, and A.
Zelevinsky), we identify frieze points of both geometrically as
certain positive integral points in explicitly described affine varieties and
Lie theoretically (in the finite case) in terms of reduced double Bruhat cells
and generalized minors on the associated semi-simple Lie groups.Comment: 47 page
Tropical patterns from the Fock-Goncharov pairing and Ringel's conjectures
We study tropical friezes and cluster-additive functions associated to
symmetrizable generalized Cartan matrices in the framework of Fock-Goncharov
duality in cluster algebras. As a special case, we generalize and prove two
conjectures of C. M. Ringel on cluster-additive functions for arbitrary Cartan
matrices of finite type
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