Abstract: Terwilliger algebra is an important tool for characterizing the local structure of distance-regular graphs, but there are few researches on characterizing the structure of general graphs by the Terwilliger algebra. In this paper, the Terwilliger algebras of a fan graph is studied. Firstly, it is proved that Terwilliger algebras keep isomorphism under the action of automorphism group on graph and the automorphism group of the fan graph is given. Secondly, the structure of irreducible modules for each of Terwilliger algebras of the fan graphs is determined. As a result, a necessary and sufficient condition for the isomorphism between the Terwilliger algebra for a fixed vertex and the centralizer algebra of stabilizer of the automorphism group of the fan graph is obtained.
Keywords: Terwilliger algebra; fan graph; centralizer algebra; irreducible module