Creating a Horizon

Description

To create a new horizon in the Model Tree:

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

  2. From the Edit menu select Insert – Other (or press the <Insert> key)

  3. In the dialog box select img_def_Identifier_Horizon_bmp Horizon and press OK

  4. Enter a name for the new horizon

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

The newly created horizon is not yet ready for use, because you should at least specify some mandatory attributes. To modify the attributes of the newly created horizon:

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

The most commonly used attributes of a horizon identifier are discussed below.

  • SUBSET OF: The SUBSET OF attribute should be specified in order to declare a subset. The img_def_Wizard_button_bmp wizard will display the Set Dependency Tree of your model and allows you to select one or more sets.

  • INDEX: The INDEX attribute is the place to declare indices in the current horizon. The img_def_Wizard_button_bmp wizard allows you to declare new index, delete or rename an existing index or move an index to another set.

  • PARAMETER: The PARAMETER attribute is like the INDEX attribute except that it allows you to declare scalar element parameters (instead of indices) in the current horizon.

  • DEFINITION: The DEFINITION attribute is mandatory and should be used to determine the ordering of the periods in the horizon.

  • CURRENT PERIOD: The CURRENT PERIOD attribute is used to specify the first period of the planning interval. The CURRENT PERIOD attribute together with the INTERVAL LENGTH attribute determine the generation of constraints and variables in your model. The img_def_Wizard_button_bmp wizard will display an Identifier Selection Dialog box containing all element parameters that are defined over the current horizon.

  • INTERVAL LENGTH: The INTERVAL LENGTH attribute is used to specify the number of periods that should be considered during the model generation. If not specified, all periods from the current period onward are part of the planning interval.

Remark

A horizon is a special kind of set. When variables and constraints are indexed over a horizon, AIMMS automatically restricts the generation of these constraints and variables to periods within the planning interval.

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