Let t(G) denote the number of spanning trees of a graph G. A chain of two
connected vertices u, v(dG(u), dG(v) ≥ 3) in G, denoted by Lk, is defined as a
path of G and dG(p) = 2 for all p ∈ V (Lk) − {u, v}, where k is the length of the
path. In this paper, we investigate the relationship between t(G) and Lk of a
graph G. In particular, the relationship between t(G) and Lk of τ-optimal graph
G is considered.