Identifier Declarations

Identifier types

Identifiers are the unique names through which you can refer to entities in your model. The most common identifier types in AIMMS are:

  • set-used for indexing parameters and variables,

  • parameter-for (multidimensional) data storage,

  • variable and arc-entities of constraints that must be determined,

  • constraint and node-relationships between variables or arcs, usually in the form of (in)equalities,

  • mathematical program-an objective and a collection of constraints, and

  • procedure and function-code segments to initiate execution.

Declaration forms

The declarations of all identifiers, procedures and functions within an AIMMS application can be provided by means of a uniform attribute notation. For every node within the model tree you can view and change the value of these attributes through a graphical declaration form. This form will show all the attributes that are associated with a particular identifier type, along with their values for the identifier at hand.

Notation used in this manual

In this manual we have chosen to use a textual style representation of all model declarations, which closely resembles the graphical representation in the model tree. In view of the large number of declarations in this manual, we found that a purely graphical presentation in the text was visually distracting. In contrast, the adopted textual representation is succinct and integrates well with the surrounding text.

The Text and Comment attributes

With every declaration in a model you can associate a Text and a Comment attribute. The Comment attribute is aimed at the modeler, and can be used to describe the contents of a particular node in the model tree, or make remarks that are relevant for later reference. The Text attribute is intended for use in the graphical user interface and reporting. It can contain a single line description of the identifier at hand. Many objects in the AIMMS user interface allow you to display this text along with the identifier value(s).

Predefined identifiers

Not only does an AIMMS model consist of sets, parameters and variables that have been defined by you, and thus are specific for your application, AIMMS also provides a number of predefined system identifiers. These identifiers characterize either

In most cases these identifiers are read-only, and get their value based on the declarations and settings of your model.

Section identifiers

The structuring sections in your model tree are also considered as AIMMS identifiers. The blanks in a section description are replaced by underscores to form a legal AIMMS identifier name. The identifier thus formed is a subset of AllIdentifiers. This subset contains all the model identifiers that have been declared underneath the associated node. You can conveniently use such sets in, for instance, the EMPTY statement to clean a entire group of identifiers in a single statement, or to construct your own subsets of AllIdentifiers using the set operations available in AIMMS.