Class SolverBase

The solver base class. This class provides functionality for the ModelTransformation that needs to be supported by all solver adapters.

Inheritance

System.Object

SolverBase

GenericSolverBase<T>

Inherited Members

System.Object.ToString()

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

Namespace: OPTANO.Modeling.Optimization

Assembly: Optimization.dll

Syntax

public abstract class SolverBase : ISolver, ICanSolve<Model, Solution>, IAbortable, IDisposable

Constructors

SolverBase(SolverConfiguration, NativeMultiObjectiveSupport, MinOperatorReplacement, MaxOperatorReplacement, FloorOperatorReplacement, CeilOperatorReplacement, AbsOperatorReplacement, NotConstraintReplacement, OrConstraintReplacement, ImplicationConstraintReplacement, SOSHandling, SOSHandling, SOSHandling, TriviallyFeasibleConstraintHandling)

Initializes a new instance of the SolverBase class. If any operator replacement has the value DoNotReplace, the SolverAdapter needs to handle that OperatorExpression type manually.

Declaration

protected SolverBase(SolverConfiguration config, NativeMultiObjectiveSupport nativeMultiObjectiveSupport = NativeMultiObjectiveSupport.Unsupported, MinOperatorReplacement minOperatorReplacement = MinOperatorReplacement.ReplaceWithDefaultMethod, MaxOperatorReplacement maxOperatorReplacement = MaxOperatorReplacement.ReplaceWithDefaultMethod, FloorOperatorReplacement floorOperatorReplacement = FloorOperatorReplacement.ReplaceWithDefaultMethod, CeilOperatorReplacement ceilOperatorReplacement = CeilOperatorReplacement.ReplaceWithDefaultMethod, AbsOperatorReplacement absOperatorReplacement = AbsOperatorReplacement.ReplaceWithDefaultMethod, NotConstraintReplacement notConstraintReplacement = NotConstraintReplacement.ReplaceWithDefaultMethod, OrConstraintReplacement orConstraintReplacement = OrConstraintReplacement.ReplaceWithDefaultMethod, ImplicationConstraintReplacement implicationConstraintReplacement = ImplicationConstraintReplacement.ReplaceWithDefaultMethod, SOSHandling sos1Handling = SOSHandling.Emulated, SOSHandling sos2Handling = SOSHandling.Emulated, SOSHandling sos3Handling = SOSHandling.Emulated, TriviallyFeasibleConstraintHandling trivialConstraintHandling = TriviallyFeasibleConstraintHandling.Native)

Parameters

Type	Name	Description
SolverConfiguration	config
NativeMultiObjectiveSupport	nativeMultiObjectiveSupport	The native support for multiobjective optimization.
MinOperatorReplacement	minOperatorReplacement	The desired MinOperatorReplacement method.
MaxOperatorReplacement	maxOperatorReplacement	The desired MaxOperatorReplacement method.
FloorOperatorReplacement	floorOperatorReplacement	The desired FloorOperatorReplacement method.
CeilOperatorReplacement	ceilOperatorReplacement	The desired CeilOperatorReplacement method.
AbsOperatorReplacement	absOperatorReplacement	The desired AbsOperatorReplacement method.
NotConstraintReplacement	notConstraintReplacement	The desired NotConstraintReplacement method.
OrConstraintReplacement	orConstraintReplacement	The desired OrConstraintReplacement method.
ImplicationConstraintReplacement	implicationConstraintReplacement	The desired OPTANO.Modeling.Optimization.SolverBase.ImplicationConstraintReplacement method.
SOSHandling	sos1Handling	The indicator whether SOS of type S1 should be handled by the solver adapter iteself (Native), or by the ModelTransformation (Emulated).
SOSHandling	sos2Handling	The indicator whether SOS of type S2 should be handled by the solver adapter iteself (Native), or by the ModelTransformation (Emulated).
SOSHandling	sos3Handling	The indicator whether SOS of type S3 should be handled by the solver adapter iteself (Native), or by the ModelTransformation (Emulated).
TriviallyFeasibleConstraintHandling	trivialConstraintHandling	If the solver cannot handle trivially feasible constraints, the user needs to make sure to remove them from the model before calling Solve(Model, Dictionary<Variable, Double>).

Fields

_busyLock

The busy lock object.

Declaration

protected readonly object _busyLock

Field Value

Type	Description
System.Object

CachedMergedObjectives

Declaration

protected Dictionary<int, Tuple<int, Objective>> CachedMergedObjectives

Field Value

Type	Description
System.Collections.Generic.Dictionary<System.Int32, System.Tuple<System.Int32, Objective>>

Properties

_model

Gets or sets the model that this GenericSolverBase<T> is working on.

Declaration

protected Model _model { get; set; }

Property Value

Type	Description
Model

Configuration

Gets or sets the configuration as SolverConfiguration. To get the solver specific {T}-configuration, cast the ISolver (or SolverBase) variable to GenericSolverBase<T>.

Declaration

public SolverConfiguration Configuration { get; set; }

Property Value

Type	Description
SolverConfiguration

Implements

ISolver.Configuration

CurrentModel

Gets the current Model.

Declaration

public Model CurrentModel { get; }

Property Value

Type	Description
Model

IsMultiHierachicalModel

Gets a value indicating whether model is multi hierachical.

Declaration

protected bool IsMultiHierachicalModel { get; }

Property Value

Type	Description
System.Boolean

Transformation

Gets the transformation helper.

Declaration

protected ModelTransformation Transformation { get; }

Property Value

Type	Description
ModelTransformation

TriviallyFeasibleConstraintHandling

Gets the support level for trivial feasible constraints, such as "c: 1 <= 2". If Unsupported, the user needs to remove all trivial constraints from the model before calling Solve(Model, Dictionary<Variable, Double>).

Declaration

public TriviallyFeasibleConstraintHandling TriviallyFeasibleConstraintHandling { get; }

Property Value

Type	Description
TriviallyFeasibleConstraintHandling

Methods

Abort()

Aborts the current optimization.

Declaration

public abstract void Abort()

Implements

IAbortable.Abort()

AddObjective(Objective)

Internal method to add an Objective to the current solver model. Should be called from the OPTANO.Modeling.Optimization.Solver.Interfaces.ICanManipulateANativeSolver.AddObjective(OPTANO.Modeling.Optimization.Objective) method. This method does not check whether the solver .

Declaration

protected abstract void AddObjective(Objective objective)

Parameters

Type	Name	Description
Objective	objective	The objective to add

BuildSolverModelAdapterSpecific(Int32)

This method needs to build the solver API's specific model from the current OPTANO Model. It is important to perform the whole work in this call, since benchmark statistics, such as required RAM, and time to build the model, are gathered during the execution of this method.

Declaration

protected abstract void BuildSolverModelAdapterSpecific(int prioLevel = 0)

Parameters

Type	Name	Description
System.Int32	prioLevel	The prio Level.

CanExportFile(FileInfo, ExportTime, Boolean)

Determines a value indicating whether this solver can export the current _model.

Declaration

protected virtual bool CanExportFile(FileInfo outputFile, ExportTime exportTime, bool printHints = false)

Parameters

Type	Name	Description
System.IO.FileInfo	outputFile	The file to export.
ExportTime	exportTime	Export before or after solve.
System.Boolean	printHints	True to print hints for the user, why his model is not exported.

Returns

Type	Description
System.Boolean	true, iff the _model can be handled by ExportFileSolverSpecific(FileInfo). Default check: ModelOutputFile != null && System.IO.Path.GetExtension(System.String)(ModelOutputFile.FullName) != System.String.Empty && !IsMultiHierachicalModel.

ClearLastModel()

Clears the last model.

Declaration

public abstract void ClearLastModel()

Implements

ISolver.ClearLastModel()

Dispose()

Declaration

public void Dispose()

Implements

System.IDisposable.Dispose()

DisposeCustom()

Disposes this solver instance. For solvers such as the GurobiSolver, the license that was used for the solver instance is freed when this method is called.

Declaration

protected virtual void DisposeCustom()

ExportFileSolverSpecific(FileInfo)

This method will be called right after (the first call of) BuildSolverModelAdapterSpecific(Int32) and should utilize the Solver-built in capabilities to export models in different file formats. By default this method only exports models as LP, using the LPExporter.

@Devs: Don't forget to check if IsMultiHierachicalModel and to return false for CanExportFile(FileInfo, ExportTime, Boolean), if your solver cannot export such a model correctly!

ExportFileSolverSpecific(FileInfo) and CanExportFile(FileInfo, ExportTime, Boolean) will only be called, if ModelOutputFile is not null.

Declaration

protected virtual void ExportFileSolverSpecific(FileInfo filteredFileToWrite)

Parameters

Type	Name	Description
System.IO.FileInfo	filteredFileToWrite

GetMergedObjectiveForPriorityLevel(Int32, Boolean)

Get the Objective for the given prioLevel. This can either be an unmodified objective, if there exists only 1 objective for the given prioLevel, or a merged objective, if there are more than 1 objective for the given prioLevel. The merged objective's Sense will be Minimize.

Declaration

protected Objective GetMergedObjectiveForPriorityLevel(int prioLevel, bool tryGetCached)

Parameters

Type	Name	Description
System.Int32	prioLevel	The priority level.
System.Boolean	tryGetCached	If value is true, the last computed Objective for the given prioLevel will be returned without recomputing it. Only use this if you know what your're doing.

Returns

Type	Description
Objective	The Objective.

GetRelevantObjectivesForPrioLevel(Int32)

Declaration

protected Objective[] GetRelevantObjectivesForPrioLevel(int prioLevel)

Parameters

Type	Name	Description
System.Int32	prioLevel

Returns

Type	Description
Objective[]

RebuildSolverModelAdapterSpecific(Int32)

This method should rebuild the required parts of the Model in the specific Solver-API when a resolve happens. By default, BuildSolverModelAdapterSpecific(Int32) is called, which means that the whole model will be rebuilt. For many solvers, this might not be the intended behavior, since they support warm starts (i.e. efficient resolves without rebuilding of the whole model). Make sure to override this method accordingly.

Declaration

protected virtual void RebuildSolverModelAdapterSpecific(int prioLevel = 0)

Parameters

Type	Name	Description
System.Int32	prioLevel	The priority level.

RemoveConstraint(String)

Internal method to remove a constraint from the current solver model. Should be called from the OPTANO.Modeling.Optimization.Solver.Interfaces.ICanManipulateANativeSolver.RemoveConstraint(System.String) method. This method does not check whether the solver .

Declaration

protected abstract void RemoveConstraint(string name)

Parameters

Type	Name	Description
System.String	name	The Name of the constraint to remove.

ResolveAdapterSpecific(Int32, IDictionary<Variable, Double>)

This method is called, if the passed Model reference of Solve(Model, Dictionary<Variable, Double>) equals the last solved CurrentModel in this solver instance. If your solver can benefit from, e.g., a warm start, override this method and implement the steps that are required to resolve a known Model. By default, this method will simply call SolveAdapterSpecific(Int32, IDictionary<Variable, Double>), i.e. you will not benefit from any warmstart capabilieties of your solver.

Declaration

protected virtual Solution ResolveAdapterSpecific(int prioLevel = 0, IDictionary<Variable, double> variableValues = null)

Parameters

Type	Name	Description
System.Int32	prioLevel	The priority level to resolve for.
System.Collections.Generic.IDictionary<Variable, System.Double>	variableValues	The start values.

Returns

Type	Description
Solution	The Solution.

RestoreModel(Solution)

Restores the model to the initial user input. I.e. all changes that were performed by TransformModel() are reverted.

Declaration

protected void RestoreModel(Solution solution)

Parameters

Type	Name	Description
Solution	solution	The solution.

SetBranchingDirectionAdapterSpecific()

If the solver adapter supports BranchingDirection, override this method and set the respective BranchingDirection. By default, a warning message will be printed, if BranchingDirection is set for at least one Variable in the current Model and the value will be ignored.

Declaration

protected virtual void SetBranchingDirectionAdapterSpecific()

SetBranchingPriorityAdapterSpecific()

If the solver adapter supports BranchingPriority, override this method and set the respective priorities. By default, a warning message will be printed, if BranchingPriority is set for at least one Variable in the current Model and the value will be ignored.

Declaration

protected virtual void SetBranchingPriorityAdapterSpecific()

SetConfigurationAdapterSpecific()

This method is called before every (re-)solve and should set all parameters from the adapter's Configuration in the respective solver.

Declaration

protected abstract void SetConfigurationAdapterSpecific()

SetMultiHierarchicalInterruptionCallback(SolverBase.InterruptMultiHierarchicalOptimization)

Sets the given callback with which the user can specify whether a multi hierarchical optimization should be interrupted.

Declaration

public void SetMultiHierarchicalInterruptionCallback(SolverBase.InterruptMultiHierarchicalOptimization callback)

Parameters

Type	Name	Description
SolverBase.InterruptMultiHierarchicalOptimization	callback	The callback delegate.

Implements

ISolver.SetMultiHierarchicalInterruptionCallback(SolverBase.InterruptMultiHierarchicalOptimization)

SetTimelimitAndGapForCurrentStage(Int32, TimeSpan, Double)

Declaration

protected virtual void SetTimelimitAndGapForCurrentStage(int prioLevel, TimeSpan timeoutForStage, double mipGapForStage)

Parameters

Type	Name	Description
System.Int32	prioLevel
System.TimeSpan	timeoutForStage
System.Double	mipGapForStage

Solve(Model, Dictionary<Variable, Double>)

Solves the specified model. This includes the TransformCurrentModel(), calling the SolveAdapterSpecific(Int32, IDictionary<Variable, Double>) solve-method OR the ResolveAdapterSpecific(Int32, IDictionary<Variable, Double>) solve-method, depending on the model. If your SolverAdapter can benefit from a Resolve make sure to override the ResolveAdapterSpecific(Int32, IDictionary<Variable, Double>) method to do that job. By default, the resolve-method reroutes to SolveAdapterSpecific(Int32, IDictionary<Variable, Double>). After a solution is obtained, the model can be restored, i.e. the changes that were performed by TransformCurrentModel() are reverted, if the user specifies this by setting RestoreUserModelAfterSolve to true.

If specified in CopySolutionToModel, the results of a solved Model will automatically be written in the OPTANO.Modeling's Variables.

Declaration

public virtual Solution Solve(Model model, Dictionary<Variable, double> variableValues = null)

Parameters

Type	Name	Description
Model	model	The Model to solve.
System.Collections.Generic.Dictionary<Variable, System.Double>	variableValues	The starting values to pass as initial solution.

Returns

Type	Description
Solution	The Solution. Before accessing the VariableValues, make sure that the Model is Feasible and the Solution is Feasible or Optimal.

Implements

ICanSolve<M, S>.Solve(M, Dictionary<Variable, Double>)

SolveAdapterSpecific(Int32, IDictionary<Variable, Double>)

This method should solve the CurrentModel, which is set in Solve(Model, Dictionary<Variable, Double>), before SolveAdapterSpecific(Int32, IDictionary<Variable, Double>) is called.

Declaration

protected abstract Solution SolveAdapterSpecific(int prioLevel = 0, IDictionary<Variable, double> variableValues = null)

Parameters

Type	Name	Description
System.Int32	prioLevel	The priority level to solve for.
System.Collections.Generic.IDictionary<Variable, System.Double>	variableValues	The variable values.

Returns

Type	Description
Solution	The Solution.

TransformModel()

Can transform the constraints of the model that contain OperatorExpressions as, e.g., Min into new expressions where these expressions are replaced by new variables and constraints. This means that in the model also some implicit variables marking new representing variables are set. Furthermore, the operator constraints can be translated into common Constraints, so that they can be handled by default MIP solvers. The resulting constraints will be added to the current model. Each individual operator (for expressions and constraints) can be controlled via the System.Enum properties in SolverBase.

Declaration

protected void TransformModel()

Extension Methods

ExtensionMethods.Clone<T>(T)

ExtensionMethods.ThrowIfArgumentIsNull<T>(T, String)

ReflectionHelper.GetFieldValue(Object, String)

ReflectionHelper.SetFieldValue(Object, String, Object)