Presolve Remove Duplicate Variables

Type

Selection

Range

The settings listed below

Default

On

This option controls whether the AIMMS Presolver should remove duplicate variables. If two variables in a mathematical program have the same coefficient in the objective function(s) and in each constraint, then one of the variables is redundant and can be removed. Possible values are:

  • On

  • Off

For example, suppose that the variables \(X\) and \(Y\) have the same coefficient in every constraint of the mathematical program and the bounds are as follows:

\[\begin{split}-\infty \leq X \leq \infty \\ 0 \leq Y \leq \infty\end{split}\]

In this case, it is possible to fix the variable \(Y = 0\), and remove it.

Note

  • Only duplicate variables are removed for which both upper bounds (or both lower bounds) are infinite.

  • Only duplicate linear variables are removed.

  • This option has only an effect when solving a nonlinear model and the option Nonlinear Presolve is switched on, or when solving a linear, quadratic or quadratically-constrained model and the option Linear Presolve is switched on, or if the function GMP::Instance::CreatePresolved is used.

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