org.chocosolver.solver.constraints.IDecompositionFactory Maven / Gradle / Ivy
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/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2019, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.solver.constraints;
import gnu.trove.iterator.TIntIterator;
import gnu.trove.set.hash.TIntHashSet;
import org.chocosolver.solver.ISelf;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.constraints.extension.Tuples;
import org.chocosolver.solver.constraints.nary.automata.FA.IAutomaton;
import org.chocosolver.solver.variables.BoolVar;
import org.chocosolver.solver.variables.IntVar;
import java.util.Arrays;
import static java.lang.Integer.MAX_VALUE;
import static java.lang.Integer.MIN_VALUE;
import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.lang.String.format;
/**
* An interface dedicated to list decomposition of some constraints.
*
* Project: choco-solver.
*
* @author Charles Prud'homme
* @since 12/06/2018.
*/
public interface IDecompositionFactory extends ISelf {
/**
* Creates and posts a decomposition of a cumulative constraint: associates a boolean
* variable to each task and each point of time sich that the scalar product of boolean
* variables per heights for each time never exceed capacity.
*
* @param starts starting time of each task
* @param durations processing time of each task
* @param heights resource consumption of each task
* @param capacity resource capacity
* @see org.chocosolver.solver.constraints.IIntConstraintFactory#cumulative(IntVar[], int[],
* int[], int)
*/
default void cumulativeTimeDec(IntVar[] starts, int[] durations, int[] heights, int capacity) {
int n = starts.length;
// 1. find range of 't' parameters while creating variables
int min_t = MAX_VALUE, max_t = MIN_VALUE;
for (int i = 0; i < n; i++) {
min_t = min(min_t, starts[i].getLB());
max_t = max(max_t, starts[i].getUB() + durations[i]);
}
for (int t = min_t; t <= max_t; t++) {
BoolVar[] bit = ref().boolVarArray(format("b_%s_", t), n);
for (int i = 0; i < n; i++) {
ref().addClausesBoolAndArrayEqVar(
new BoolVar[]{
ref().intLeView(starts[i], t),
ref().intGeView(starts[i], t - durations[i] + 1)
},
bit[i]);
}
ref().scalar(
bit,
Arrays.stream(heights, 0, n).toArray(),
"<=",
capacity
).post();
}
}
/**
* Creates and posts a decomposition of a regular constraint.
* Enforces the sequence of vars to be a word
* recognized by the deterministic finite automaton.
* For example regexp = "(1|2)(3*)(4|5)";
* The same dfa can be used for different propagators.
*
* @param vars sequence of variables
* @param automaton a deterministic finite automaton defining the regular language
* @return array of variables that encodes the states, which can optionally be constrained too.
*/
default IntVar[] regularDec(IntVar[] vars, IAutomaton automaton) {
int n = vars.length;
IntVar[] states = new IntVar[n + 1];
TIntHashSet[] layer = new TIntHashSet[n + 1];
for (int i = 0; i <= n; i++) {
layer[i] = new TIntHashSet();
}
layer[0].add(automaton.getInitialState());
states[0] = ref().intVar("Q_0", layer[0].toArray());
TIntHashSet nexts = new TIntHashSet();
for (int i = 0; i < n; i++) {
int ub = vars[i].getUB();
Tuples tuples = new Tuples(true);
for (int j = vars[i].getLB(); j <= ub; j = vars[i].nextValue(j)) {
TIntIterator layerIter = layer[i].iterator();
while (layerIter.hasNext()) {
int k = layerIter.next();
nexts.clear();
automaton.delta(k, j, nexts);
for (TIntIterator it = nexts.iterator(); it.hasNext(); ) {
int succ = it.next();
if (i + 1 < n || automaton.isFinal(succ)) {
layer[i + 1].add(succ);
tuples.add(k, succ, j);
}
}
}
}
states[i + 1] = ref().intVar("Q_" + (i + 1), layer[i + 1].toArray());
ref().table(new IntVar[]{states[i], states[i + 1], vars[i]}, tuples).post();
}
return states;
}
/**
* Creates and posts a decomposition of a bin packing constraint. Bin Packing
* formulation: forall b in [0,binLoad.length-1], load[b]=sum(w[i] | i in [0,w.length-1], bin[i]
* = b+offset) forall i in [0,w.length-1], bin is in [offset,load.length-1+offset],
*
* @param bin IntVar representing the bin of each item
* @param w int representing the size of each item
* @param load IntVar representing the load of each bin (i.e. the sum of the size of the items
* in it)
* @param offset 0 by default but typically 1 if used within MiniZinc (which counts from 1 to n
* instead of from 0 to n-1)
*/
default void binPackingDec(IntVar[] bin, int[] w, IntVar[] load, int offset) {
ref().sum(load, "=", Arrays.stream(w).sum()).post();
for (int i = 0; i < bin.length; i++) {
ref().member(bin[i], offset, load.length - 1 + offset).post();
}
for (int i = 0; i < load.length; i++) {
BoolVar[] in = new BoolVar[bin.length];
for (int j = 0; j < bin.length; j++) {
in[j] = ref().intEqView(bin[j], i + offset);
}
ref().scalar(in, w, "=", load[i]).post();
}
}
}