Generators of rank 2 cluster algebras of affine types via linearization of seed mutations

Abstract: From the viewpoint of integrable systems on algebraic curves, we discuss linearization of birational maps arising from the seed mutations of types $A^{(1)}_1$ and $A^{(2)}_2$, which enables us to construct the set of all cluster variables generating the corresponding cluster algebras. These birational maps respectively induce discrete integrable systems on algebraic curves referred to as the types of the seed mutations from which they are arising. The invariant curve of type $A^{(1)}_1$ is a conic, while the one of type $A^{(2)}_2$ is a singular quartic curve. By applying the blowing-up of the singular quartic curve, the discrete integrable system of type $A^{(2)}_2$ on the singular curve is transformed into the one on the conic, the invariant curve of type $A^{(1)}_1$. We show that the both discrete integrable systems of types $A^{(1)}_1$ and $A^{(2)}_2$ commute with each other on the conic, the common invariant curve. We moreover show that these integrable systems are simultaneously linearized by means of the conserved quantities and their general solutions are respectively obtained. By using the general solutions, we construct the sets of all cluster variables generating the cluster algebras of types $A^{(1)}_1$ and $A^{(2)}_2$, respectively.