# lec23 - Click to edit Master subtitle style 2/7/11 Sundar...

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Unformatted text preview: Click to edit Master subtitle style 2/7/11 Sundar B. CS C341 / I S C361 Data Structures & Algorithms Algorithm Design Techniques Dynamic Programming- Examples- Matrix-Chain Multiplication- Sequence Alignment 11 2/7/11 Sundar B. 2/7/11 Sundar B. Example – Matrix-Chain Multiplication Consider the following expression: M1 * M2 * M3 where Mj is a matrix of dimensions pj-1 * pj for j = 1 to 3 Matrix Multiplication is associative i.e. (M1 * M2 ) * M3 = M1 * (M2 * M3) Exercise: Prove this. Hint: Use Induction. Then the above expression can be evaluated either as (M1 * M2 )* M3 2/7/11 22 Sundar B. 2/7/11 Sundar B. Example – Matrix-Chain Multiplication Consider the following generalized expression: M1 * M2 * … * Mn where Mj is a matrix of dimensions pj-1 * pj for j = 1 to n Problem: Given the above expression, how do we minimize the number of scalar multiplications? This depends on the way the expression is parenthesized (which determines the order of evaluation) Definition: 2/7/11 33 Sundar B. 2/7/11 Sundar B. Example – McM - Brute Force Solution Algorithm BF_MCM: Find all possible parenthesizations For each possible parenthesization, count the scalar multiplications required....
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## This note was uploaded on 02/07/2011 for the course CS 123 taught by Professor Murali during the Spring '11 term at Birla Institute of Technology & Science, Pilani - Hyderabad.

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lec23 - Click to edit Master subtitle style 2/7/11 Sundar...

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