How Does Unique Edge Weighting Guarantee a Singular Minimum Spanning Tree?

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In summary, to prove that a weighted graph with unique edge weights has only one minimum spanning tree, one can use a contradiction by assuming there are two minimum spanning trees of equal weight and considering the edge that is in one tree but not the other. Alternatively, Kruskal's Algorithm can be used, as it creates a unique sequence of edges with increasing costs, resulting in a unique minimum spanning tree for the graph.
  • #1
find_the_fun
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Prove that if a weighted graph has unique weights on each edge that there is only 1 minimum spanning tree. Do I need to use an algorithm such as Prim's to show this or do I use properties of weighted graphs?
 
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Try contradiction. Assume you have two MST's of equal weight. Consider what happens with an edge that's in one MST but not the other (there must be at least one such edge if the MST's are not the same).
 
  • #3
Kruskal's Algorithm can be used here as follows:

If edge costs are all distinct then running Kruskal's Algorithm on this graph G(say) creates only a unique sequence of (n-1) edges with edge costs in increasing order. Hence G has a unique minimum spanning tree.
 

Related to How Does Unique Edge Weighting Guarantee a Singular Minimum Spanning Tree?

1. What is a weighted graph?

A weighted graph is a type of graph where each edge has a numerical value associated with it, known as a weight. This weight represents the cost or distance between two vertices in the graph.

2. How do you represent a weighted graph?

A weighted graph can be represented using an adjacency matrix or an adjacency list. In an adjacency matrix, the weights are stored in a matrix format where rows and columns represent the vertices. In an adjacency list, the weights are stored as a list of edges and their corresponding weights.

3. What is the purpose of using weights in a graph?

The weights in a graph can represent various real-world scenarios, such as the cost of traveling between cities or the distance between two locations. They can also be used in algorithms to find the shortest path or minimum spanning tree in a graph.

4. How do you find the shortest path in a weighted graph?

To find the shortest path in a weighted graph, you can use algorithms such as Dijkstra's algorithm or the Bellman-Ford algorithm. These algorithms take into account the weights of the edges and find the shortest path between two vertices in the graph.

5. Can a weighted graph have negative weights?

Yes, a weighted graph can have negative weights. However, it can cause issues with certain algorithms, such as Dijkstra's algorithm, as it assumes all edge weights are positive. In such cases, other algorithms like the Bellman-Ford algorithm can be used instead.

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