The Decomposition Algorithm

Getting Started: Decomposition Algorithm

This example illustrates how you can use the decomposition algorithm to solve a simple mixed integer linear program. Suppose you want to solve the following problem:

StartLayout 1st Row 1st Column maximize 2nd Column x 11 3rd Column plus 4th Column 2 x 21 5th Column plus 6th Column x 31 7th Column Blank 8th Column Blank 9th Column plus 10th Column x 22 11th Column plus 12th Column x 32 2nd Row 1st Column subject to 2nd Column x 11 3rd Column Blank 4th Column Blank 5th Column Blank 6th Column Blank 7th Column plus 8th Column x 12 9th Column Blank 10th Column Blank 11th Column Blank 12th Column Blank 13th Column greater-than-or-equal-to 14th Column 1 15th Column left-parenthesis m right-parenthesis 3rd Row 1st Column Blank 2nd Column 5 x 11 3rd Column plus 4th Column 7 x 21 5th Column plus 6th Column 4 x 31 7th Column Blank 8th Column Blank 9th Column Blank 10th Column Blank 11th Column Blank 12th Column Blank 13th Column less-than-or-equal-to 14th Column 11 15th Column left-parenthesis s 1 right-parenthesis 4th Row 1st Column Blank 2nd Column Blank 3rd Column Blank 4th Column Blank 5th Column Blank 6th Column Blank 7th Column Blank 8th Column x 12 9th Column plus 10th Column 2 x 22 11th Column plus 12th Column x 32 13th Column less-than-or-equal-to 14th Column 2 15th Column left-parenthesis s 2 right-parenthesis 5th Row 1st Column Blank 2nd Column Blank 3rd Column Blank 4th Column Blank 5th Column Blank 6th Column Blank 7th Column Blank 8th Column Blank 9th Column Blank 10th Column Blank 11th Column Blank 12th Column x Subscript i j 13th Column element-of 14th Column StartSet 0 comma 1 EndSet 15th Column i element-of StartSet 1 comma 2 comma 3 EndSet comma j element-of StartSet 1 comma 2 EndSet EndLayout

It is obvious from the structure of the problem that if constraint m is removed, then the remaining constraints s1 and s2 decompose into two independent subproblems. The next two sections describe how to solve this MILP by using the decomposition algorithm in the OPTMODEL procedure and OPTMILP procedure, respectively.

Last updated: April 14, 2021