Let G=(V,E) be an undirected graph. Prove that if all its edge weights are distinct, then it has a unique minimum spanning tree

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Here, we get undirected graph G. Given here to prove non - negative real edge weights, and presume that even if you calculated a minimal spanning tree of G and the short distance for that kind of node, it accepts particular nodesV.

Step by step solution

01

Two alternative shortest path trees

If most of the parameters associated in such an undirected graph disagree, the graph has a single minimal spanning tree.

• Assume there are two alternative shortest path trees inside of an undirected graph, including such T1andT2.

• Let e1seems to be the minimal side weight which relates to a few of the trees, for example. e1T1.

• Including the side role="math" localid="1658904910955" e1into the tree T2making of cycle. The cycle includes the edge of role="math" localid="1658904901130" e2in tree T2, any one is bigger than e1.

• This seems to be an inconsistency for which an indifference curve has two distinct minimum spanning trees.

02

Proof of theoem.

Using the cut property, find the minimal spanning tree based on the graph's topology and edge weight order.

The minimal side value is already on the lowest spanning tree for each and every cut.

• Since all of the respect to the weights inside a graph are different, then all of the cuts are unique.

• If all of the edge weights in a graph are the same, the outcome may be unclear.

If all the edge weights of a graph are distinct, the smallest spanning tree is unique.

For example:

Consider the undirected graph G = (V, E) is given below:

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Most popular questions from this chapter

Question: Suppose the symbols a,b,c,d,e occur with frequencies 12,14,18,116,116,respectively.

(a) What is the Huffman encoding of the alphabet?

(b) If this encoding is applied to a file consisting of1,000,1000 characters with the given frequencies, what is the length of the encoded file in bits?

Show that if an undirected graph with n vertices has k connected components, then it has at least n - k edges.

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However, words like fire!, help!, and run! are short not because they are frequent, but perhaps because time is precious in situations where they are used.

To make things theoretical, suppose we have a file composed of m different words, with frequencies f1,...,fm. Suppose also that for the ithword, the cost per bit of encoding is ci. Thus, if we find a prefix-free code where the ithword has a codeword of length Ii, then the total cost of the encoding will be localid="1659078764835" fi·ci·li.

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Sometimes we want light spanning trees with certain special properties. Here’s an example.

Input: Undirected graph G=(V,E) ; edge weights we; subset of vertices UV

Output: The lightest spanning tree in which the nodes of U are leaves (there might be other leaves in this tree as well).

(The answer isn’t necessarily a minimum spanning tree.)

Give an algorithm for this problem which runs in O(ElogV) time. (Hint: When you remove nodes Ufrom the optimal solution, what is left?)

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