A cluster algebra is a commutative algebra whose structure is decided by a skew
symmetrizable matrix or a valued quiver. When a skew symmetrizable matrix is invariant
under an action of a finite group and this action is
admissible, the
folded cluster algebra
is obtained from the original one. Any cluster algebra of nonsimply laced affine type
can be obtained by folding a cluster algebra of simply laced affine type with a specific
-action.
In this paper, we study the combinatorial properties of quivers in the cluster
algebra of affine type. We prove that for any quiver of simply laced affine type,
-invariance and
-admissibility
are equivalent. This leads us to prove that the set of
-invariant
seeds forms the folded cluster pattern.
Keywords
cluster patterns of affine type, folding, invariance,
admissibility