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The MOSEK command line tool Version 7.0 (Revision 141)

The MOSEK command line tool. Version 7.0 ... - Documentation

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6.5. TERMINATION CRITERION 53<br />

<strong>The</strong> following parameters can be used to control the effort made by the integer optimizer to find an<br />

initial feasible solution.<br />

• MSK IPAR MIO HEURISTIC LEVEL: Controls how sophisticated and computationally expensive a<br />

heuristic to employ.<br />

• MSK DPAR MIO HEURISTIC TIME: <strong>The</strong> minimum amount of time to spend in the heuristic search.<br />

• MSK IPAR MIO FEASPUMP LEVEL: Controls how aggressively the feasibility pump heuristic is used.<br />

6.4.3 <strong>The</strong> optimization phase<br />

This phase solves the problem using the branch and cut algorithm.<br />

6.5 Termination criterion<br />

In general, it is time consuming to find an exact feasible and optimal solution to an integer optimization<br />

problem, though in many practical cases it may be possible to find a sufficiently good solution. <strong>The</strong>refore,<br />

the mixed-integer optimizer employs a relaxed feasibility and optimality criterion to determine<br />

when a satisfactory solution is located.<br />

A candidate solution that is feasible to the continuous relaxation is said to be an integer feasible<br />

solution if the criterion<br />

is satisfied.<br />

min(|x j | − ⌊x j ⌋, ⌈x j ⌉ − |x j |) ≤ max(δ 1 , δ 2 |x j |) ∀j ∈ J<br />

Whenever the integer optimizer locates an integer feasible solution it will check if the criterion<br />

¯z − z ≤ max(δ 3 , δ 4 max(1, |¯z| ))<br />

is satisfied. If this is the case, the integer optimizer terminates and reports the integer feasible solution<br />

as an optimal solution. Please note that z is a valid lower bound determined by the integer optimizer<br />

during the solution process, i.e.<br />

z ≤ z ∗ .<br />

<strong>The</strong> lower bound z normally increases during the solution process.<br />

6.5.1 Relaxed termination<br />

If an optimal solution cannot be located within a reasonable time, it may be advantageous to employ<br />

a relaxed termination criterion after some time. Whenever the integer optimizer locates an integer feasible<br />

solution and has spent at least the number of seconds defined by the MSK DPAR MIO DISABLE TERM TIME<br />

parameter on solving the problem, it will check whether the criterion

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