The phrase "minimum spanning tree" is a shortened form of the phrase "minimum-weight spanning tree." We are not, for example, minimizing the number of edges in T, since all spanning trees have exactly |V| - 1 edges by Theorem 5.2.
In this chapter, we shall examine two algorithms for solving the minimum-spanning-tree problem: Kruskal's algorithm and Prim's algorithm. Each can easily be made to run in time O(E lg V) using ordinary binary heaps. By using Fibonacci heaps, Prim's algorithm can be sped up to run in time O(E + V lg V), which is an improvement if |V| is much smaller than |E| .