OPTANO.Modeling 2.0.0.286

• • MathNet.Symbolics (= 0.11.0)

http://docs.optano.com/modeling/current/changelog.html

Version 2.0.0 has been tested to comply with dotnet standard 2.0.



• Breaking Change: Removed  and replaced it with @OPTANO.Modeling.Optimization.Implication
o The reasoning behind this is that we tried to create a more intuitive API. Since a  basically was a "backwards implication", and the constructor required a @OPTANO.Modeling.Optimization.Not-constraint, the final effect was not apparent.
o The new @OPTANO.Modeling.Optimization.Implication operator clearly states which constraint will be the @OPTANO.Modeling.Optimization.Implication.Premise and which one will be the @OPTANO.Modeling.Optimization.Implication.Premise.Conclusion.
• Breaking Change: The signature of @OPTANO.Modeling.Optimization.GenericVariableCollection{T} was changed.
o The DebugNameGenerator delegate's signature was changed to (index) => string.
 Previously: (index) => StringBuilder
o Initially, we tried to enforce the usage of @System.Text.StringBuilder in order to prevent the user specifying names with long chains of string + string + ...
o With the introduction of short names, this style will not affect performance in a productive environment.
o We'd still suggest using either string.Format(), string interpolation, or expressions like 'new @System.Text.StringBuilder().Append() ... Append().ToString().
• Improvement: Better handling of BigM
o BigM is required during the transformation of @OPTANO.Modeling.Optimization.OperatorExpressions, such as @OPTANO.Modeling.Optimization.Abs to 'linear expressions'.
 User can provide an optional BigM when such a @OPTANO.Modeling.Optimization.OperatorExpression is created.
o New implementation for the automatic derivation of a BigM
 When @OPTANO.Modeling.Optimization.Variables have finite bounds, the maximum row sum is computed and used as BigM
 Only when this fails, the user-provided BigM is used.
 If user does not provide a finite BigM, an @System.InvalidOperationException is thrown.
• Improvement: Centralized name-cleansing and unified behavior among different types (Variable, Constraint, Objective, VariableCollection, @OPTANO.Modeling.Optimization.OperatorConstraint)
o Also, Constraint and Objective now use the same counter for the base64 suffixes
o This prevents duplicate name issues when exporting a model to MPS.
• Improvement: Operator '==' now creates a nicer Constraint for 'Variable x == double c'
o Old: 0 <= x - c < 0 (even if c = 0).
o New: c <= x < c
• Change: Configuration.CopySolutionToModel == true in default (was false)
• Change: @OPTANO.Modeling.Optimization.Expression.Evaluate now requires the passed values for the @OPTANO.Modeling.Optimization.Variables to be within the range of [LowerBound, @OPTANO.Modeling.Optimization.Variable.UpperBound].
• Fix: Gurobi ISV Keys have not been handled correctly
• Fix: Improved the stability of he LP- and MPS Reader/Writers. They are used for im-/export of models when a solver does not provide a native API.
• Fix: In some cases the ExpressionNormalizer threw a @System.Collections.Generic.KeyNotFoundException. Cases now are handled correctly.
• Fix: ModelTransformation
o @OPTANO.Modeling.Optimization.OperatorExpressions were not remove from the Model after they were transformed
o Some helper-constraints were not marked as helper and thus not removed from the Model even though RestoreUserModelAfterSolve was set to true.
o Normalizing all @OPTANO.Modeling.Optimization.Expressions before transforming them
 Can prevent issues while encountering @OPTANO.Modeling.Optimization.Times operators during derivation of BigM
o In a helper method BigM falsely was used, when working with a 'lower bound @OPTANO.Modeling.Optimization.Constraint'.
• Fix: @OPTANO.Modeling.Optimization.Model.RemoveConstraint now also looks for @OPTANO.Modeling.Optimization.OperatorConstraints
o Before, @OPTANO.Modeling.Optimization.OperatorConstraints could not be removed from the Model.
Please also take the changes of alpha01 und alpha02 into account, when upgrading from version 1.6.