“…In particular, we will associate a cluster algebra to any bordered surface with marked points, following work of Fock and Goncharov [8], Gekhtman, Shapiro, and Vainshtein [20], and Fomin, Shapiro, and Thurston [11]. This construction provides a natural generalization of the type A cluster algebra from Section 2.2, and realizes the lambda lengths (also called Penner coordinates) on the decorated Teichmüller space associated to a cusped surface, which Penner had defined in 1987 [39].…”