StreakPeaked· Practice

ExamsGATETechnical

Let `w` be the minimum weight among all edge weights in an undirected connected graph. Let `e` be a specific edge of weight `w`. Which of the following is false?

  1. There is a minimum spanning tree containing `e`.
  2. If `e` is not in a minimum spanning tree `T`, then in the cycle formed by adding `e` to `T`, all edges have the same weight.
  3. Every minimum spanning tree has an edge of weight `w`.
  4. `e` is present in every minimum spanning tree.

Correct answer: `e` is present in every minimum spanning tree.

Solution

A minimum-weight edge belongs to at least one minimum spanning tree by the cut property. However, it need not appear in every MST if there are multiple minimum-weight edges or alternative equal-weight choices. Therefore, the statement claiming it is present in every MST is false.

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