The MOSEK Python optimizer API manual Version 7.0 (Revision 141)

Optimizer API for Python - Documentation - Mosek Optimizer API for Python - Documentation - Mosek

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154 CHAPTER 11. THE OPTIMIZERS FOR CONTINUOUS PROBLEMS

Chapter 12 The optimizers for mixed-integer problems A problem is a mixed-integer optimization problem when one or more of the variables are constrained to be integer valued. MOSEK contains two optimizers for mixed integer problems that is capable for solving mixed-integer • linear, • quadratic and quadratically constrained, and • conic problems. Readers unfamiliar with integer optimization are recommended to consult some relevant literature, e.g. the book [16] by Wolsey. 12.1 Some concepts and facts related to mixed-integer optimization It is important to understand that in a worst-case scenario, the time required to solve integer optimization problems grows exponentially with the size of the problem. For instance, assume that a problem contains n binary variables, then the time required to solve the problem in the worst case may be proportional to 2 n . The value of 2 n is huge even for moderate values of n . In practice this implies that the focus should be on computing a near optimal solution quickly rather than at locating an optimal solution. Even if the problem is only solved approximately, it is important to know how far the approximate solution is from an optimal one. In order to say something about the goodness of an approximate solution then the concept of a relaxation is important. 155

Chapter 12<br />

<strong>The</strong> <strong>optimizer</strong>s for mixed-integer<br />

problems<br />

A problem is a mixed-integer optimization problem when one or more of the variables are constrained<br />

to be integer valued. <strong>MOSEK</strong> contains two <strong>optimizer</strong>s for mixed integer problems that is capable for<br />

solving mixed-integer<br />

• linear,<br />

• quadratic and quadratically constrained, and<br />

• conic<br />

problems.<br />

Readers unfamiliar with integer optimization are recommended to consult some relevant literature,<br />

e.g. the book [16] by Wolsey.<br />

12.1 Some concepts and facts related to mixed-integer optimization<br />

It is important to understand that in a worst-case scenario, the time required to solve integer optimization<br />

problems grows exponentially with the size of the problem. For instance, assume that a problem<br />

contains n binary variables, then the time required to solve the problem in the worst case may be<br />

proportional to 2 n . <strong>The</strong> value of 2 n is huge even for moderate values of n .<br />

In practice this implies that the focus should be on computing a near optimal solution quickly rather<br />

than at locating an optimal solution. Even if the problem is only solved approximately, it is important<br />

to know how far the approximate solution is from an optimal one. In order to say something about<br />

the goodness of an approximate solution then the concept of a relaxation is important.<br />

155

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