On the Connectivity of Token Graphs of Trees

Let k and n be integers such that 1 <= k <= n - 1, and let G be a simple graph of order n. The k-token graph F-k(G) of G is the graph whose vertices are the k-subsets of V (G), where two vertices are adjacent in F-k(G) whenever their symmetric difference is an edge of G. In this paper we show that if G is a tree, then the connectivity of F-k(G) is equal to the minimum degree of F-k(G).