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oj! Algorithms - ojAlgo - is Open Source Java code that has to do with mathematics, linear algebra and optimisation.
There is a newer version: 55.0.1
/*
 * Copyright 1997-2024 Optimatika
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package org.ojalgo.optimisation;

import java.util.Collection;
import java.util.Collections;

import org.ojalgo.equation.Equation;
import org.ojalgo.type.PrimitiveNumber;
import org.ojalgo.type.keyvalue.EntryPair;
import org.ojalgo.type.keyvalue.EntryPair.KeyedPrimitive;

public interface UpdatableSolver extends Optimisation.Solver {

    /**
     * @param index The, solver specific, variable index
     * @param value The value to fix that variable to
     * @return true if fixing is supported and was successful, otherwise false
     */
    default boolean fixVariable(final int index, final double value) {
        return false;
    }

    default Collection generateCutCandidates(final double fractionality, final boolean... integer) {
        return Collections.emptySet();
    }

    ExpressionsBasedModel.EntityMap getEntityMap();

    /**
     * Some solvers deal with variable bounds implicitly – they are not expressed as constraints. If so, then
     * this method should return info about such implied bound slack variables.
     * 
     * The requirements are dictated by what's needed to create Gomory mixed integer cuts with solvers that
     * handle variable bounds implicitly. Currently it returns the bounded variable index, a
     * {@link ConstraintType} that indicates at which bound the variable is as well as the value at that bound
     * – type, index & value – in that order.
     * 
     * For solvers that treat variable bounds as any other constraint, this method simply always return null.
     * That's the default behaviour.
     */
    default KeyedPrimitive> getImpliedBoundSlack(final int col) {
        return null;
    }

    default boolean isMapped() {
        return this.getEntityMap() != null;
    }

    /**
     * A generalisation of {@link #fixVariable(int, double)} where the new/updated lower and upper bounds do
     * not need to be equal.
     *
     * @param index The, solver specific, variable index
     * @param lower New lower bound
     * @param upper New upper bound
     * @return true if updating the range is supported and was successful, otherwise false
     */
    default boolean updateRange(final int index, final double lower, final double upper) {
        return false;
    }

}