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minimum weighted path length (Definition)

Given a list of weights, $ W := \left\{ w_1, w_2, \dots, w_n \right\}$, the minimum weighted path length is the minimum of the weighted path length of all extended binary trees that have $ n$ external nodes with weights taken from $ W$. There may be multiple possible trees that give this minimum path length, and quite often finding this tree is more important than determining the path length.

Example

Let $ W := \left\{ 1, 2, 3, 3, 4 \right\}$. The minimum weighted path length is $ 29$. A tree that gives this weighted path length is shown below.

\includegraphics{tree.10}

Applications

Constructing a tree of minimum weighted path length for a given set of weights has several applications, particularly dealing with optimization problems. A simple and elegant algorithm for constructing such a tree is Huffman's algorithm. Such a tree can give the most optimal algorithm for merging $ n$ sorted sequences (optimal merge). It can also provide a means of compressing data (Huffman coding), as well as lead to optimal searches.




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See Also: weighted path length, extended binary tree, Huffman's algorithm, Huffman coding

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Cross-references: Huffman coding, sequences, Huffman's algorithm, algorithm, simple, applications, path length, trees, multiple, external nodes, extended binary trees, weighted path length, weights
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This is version 3 of minimum weighted path length, born on 2002-03-08, modified 2004-01-22.
Object id is 2779, canonical name is MinimumWeightedPathLength.
Accessed 6039 times total.

Classification:
AMS MSC05C05 (Combinatorics :: Graph theory :: Trees)

Pending Errata and Addenda
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how were the weights sum-ed ? by nayana on 2004-06-01 09:44:32

I refer to this "minimum weighted path length " article. Though the leaves have been added to form the next higher level of weights..how was 3(Left tree weight) & 3(Right tree weight) => 9. 9 & 7 => 29 arrived at ?
could that be clarified ?
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