Creating a Constraint

Description

To create a new constraint in the Model Tree:

  1. Select the position in a Declaration Section where the new constraint should be inserted

  2. From the Edit menu select Insert – Constraint img_def_Identifier_Constraint_bmp

  3. Enter a name for the new constraint (if you are creating a multi-dimensional constraint, you can type the indices of each dimension as well)

  4. Press <Enter> to create the new constraint (or press <Esc> to abort the operation)

The newly created constraint is not yet ready for use, because you should at least specify the definition of a constraint via its attributes. To modify the attributes of the newly created constraint:

  • Press <Enter> or double click on the constraint node.

The most commonly used attributes of a constraint are discussed below.

  • INDEX DOMAIN : The INDEX DOMAIN attribute should be specified in order to declare indexed constraints. The img_def_Wizard_button_bmp wizard will display the Set Dependency Tree of your model and allows you to select one or more indices.

  • UNIT : The UNIT attribute is used to specify the unit in which the constraint’s RHS value is measured. By specifying a unit, AIMMS is able to perform automatic unit conversions and unit consistency checks. The img_def_Wizard_button_bmp wizard will let you select a unit and quantity from the list made up from your model quantities and units together with the information in the AIMMS SI unit base.

  • PROPERTY : The PROPERTY attribute should be used to specify additional properties. Note that in order to retrieve sensitivity information from the solver, the ShadowPrices , RightHandSideRange , or ShadowPriceRange property should be explicitly set. The img_def_Wizard_button_bmp wizard will let you specify the properties through a selection of radio buttons and check boxes.

  • DEFINITION : The DEFINITION attribute is mandatory and should contain the constraint formulation containing two or three expressions separated by one of the relational operators = , <= , or >= .

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