This attribute is used to set the allowable degradation for objective when doing hierarchical multi-objective optimization. You set using the ObjNumber parameter.
Hierarchical multi-objective MIP optimization will optimize for the
different objectives in the model one at a time, in priority order.
If it achieves objective value when it optimizes for this
objective, then subsequent steps are allowed to degrade this value by
Objective degradations are handled differently for multi-objective LP
models. For LP models, solution quality for higher-priority objectives is
maintained by fixing some variables to their values in previous
optimal solutions. These fixings are decided using variable reduced
costs. The value of the
ObjNAbsTol parameter indicates the
amount by which a fixed variable's reduced cost is allowed to violate
The value of the related ObjNRelTol
attribute is ignored.
The default absolute tolerance for an objective is 0.
The number of objectives in the model can be queried (or modified) using the NumObj attribute.
Please refer to the discussion of Multiple Objectives for more information on the use of alternative objectives.
For examples of how to query or modify attributes, refer to our Attribute Examples.