org.ojalgo.optimisation

Class Presolvers

java.lang.Object

org.ojalgo.optimisation.Presolvers

public abstract class Presolvers
extends Object

Field Summary

Fields

Modifier and Type	Field and Description
static ExpressionsBasedModel.Presolver	BINARY_VALUE Deprecated. v48 Has been replaced by doCaseN(Expression, Set, BigDecimal, BigDecimal, NumberContext)
static ExpressionsBasedModel.Presolver	INTEGER_EXPRESSION_ROUNDING
static org.ojalgo.optimisation.ExpressionsBasedModel.VariableAnalyser	INTEGER_VARIABLE_ROUNDING Makes sure integer variables have integer lower/upper bounds (if they exist).
static ExpressionsBasedModel.Presolver	LINEAR_OBJECTIVE If the expression is linear and contributes to the objective function, then the contributions are transferred to the variables and the weight of the expression set to null.
static ExpressionsBasedModel.Presolver	OPPOSITE_SIGN Deprecated. v48 Has been replaced by doCaseN(Expression, Set, BigDecimal, BigDecimal, NumberContext)
static ExpressionsBasedModel.Presolver	REDUNDANT_CONSTRAINT Calculates the min and max value of this expression based on the variables' individual bounds.
static org.ojalgo.optimisation.ExpressionsBasedModel.VariableAnalyser	UNREFERENCED Verifies that the variable is actually referenced/used in some expression.
static ExpressionsBasedModel.Presolver	ZERO_ONE_TWO Looks for constraint expressions with 0, 1 or 2 non-fixed variables.

Constructor Summary

Constructors

Constructor and Description
Presolvers()

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BINARY_VALUE

@Deprecated
public static final ExpressionsBasedModel.Presolver BINARY_VALUE

Deprecated. v48 Has been replaced by doCaseN(Expression, Set, BigDecimal, BigDecimal, NumberContext)

If an expression contains at least 1 binary variable and all non-fixed variable weights are of the same sign (positive or negative) then it is possible the check the validity of "1" for each of the binary variables. (Doesn't seem to work and/or is not effective.)

INTEGER_EXPRESSION_ROUNDING

public static final ExpressionsBasedModel.Presolver INTEGER_EXPRESSION_ROUNDING

INTEGER_VARIABLE_ROUNDING

public static final org.ojalgo.optimisation.ExpressionsBasedModel.VariableAnalyser INTEGER_VARIABLE_ROUNDING

Makes sure integer variables have integer lower/upper bounds (if they exist).

LINEAR_OBJECTIVE

public static final ExpressionsBasedModel.Presolver LINEAR_OBJECTIVE

If the expression is linear and contributes to the objective function, then the contributions are transferred to the variables and the weight of the expression set to null.

REDUNDANT_CONSTRAINT

public static final ExpressionsBasedModel.Presolver REDUNDANT_CONSTRAINT

Calculates the min and max value of this expression based on the variables' individual bounds. Then compares those with the expression's bounds.

OPPOSITE_SIGN

@Deprecated
public static final ExpressionsBasedModel.Presolver OPPOSITE_SIGN

Deprecated. v48 Has been replaced by doCaseN(Expression, Set, BigDecimal, BigDecimal, NumberContext)

Checks the sign of the limits and the sign of the expression parameters to deduce variables that in fact can only be zero.

UNREFERENCED

public static final org.ojalgo.optimisation.ExpressionsBasedModel.VariableAnalyser UNREFERENCED

Verifies that the variable is actually referenced/used in some expression. If not then that variable can either be fixed or marked as unbounded.

 2019-02-15: Turned this off. Very slow for large models
 2019-02-22: Turned this on again, different implementation
 

ZERO_ONE_TWO

public static final ExpressionsBasedModel.Presolver ZERO_ONE_TWO

Looks for constraint expressions with 0, 1 or 2 non-fixed variables. Transfers the constraints of the expressions to the variables and then (if possible) marks the expression as redundant.

Constructor Detail

Presolvers

public Presolvers()