A Module-Theoretic Interpretation of Schiffler's Expansion Formula

摘要

We give a module-theoretic interpretation of Schiffler's expansion formula which is defined combinatorially in terms of complete (Γ, γ)-paths in order to get the expansion of the cluster variables in the cluster algebra of a marked surface (S, M). Based on the geometric description of the indecomposable objects of the cluster category of the marked surface (S, M), we show the coincidence of Schiffler-Thomas' expansion formula and the cluster character defined by Palu.