org.logicng.pseudobooleans.PBSWC Maven / Gradle / Ivy
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// The Next Generation Logic Library //
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// Copyright 2015-20xx Christoph Zengler //
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// Licensed under the Apache License, Version 2.0 (the "License"); //
// you may not use this file except in compliance with the License. //
// You may obtain a copy of the License at //
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// http://www.apache.org/licenses/LICENSE-2.0 //
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// distributed under the License is distributed on an "AS IS" BASIS, //
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/*
* Open-WBO -- Copyright (c) 2013-2015, Ruben Martins, Vasco Manquinho, Ines Lynce
*
* 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
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package org.logicng.pseudobooleans;
import org.logicng.collections.LNGIntVector;
import org.logicng.collections.LNGVector;
import org.logicng.formulas.Formula;
import org.logicng.formulas.FormulaFactory;
import org.logicng.formulas.Literal;
import java.util.List;
/**
* A sequential weight counter for the encoding of pseudo-Boolean constraints in CNF.
* @version 2.0.0
* @since 1.0
*/
public final class PBSWC implements PBEncoding {
private final FormulaFactory f;
/**
* Constructs a new sequential weight counter encoder.
* @param f the formula factory
*/
PBSWC(final FormulaFactory f) {
this.f = f;
}
@Override
public List encode(final LNGVector lits, final LNGIntVector coeffs, final int rhs, final List result) {
this.generateConstraint(rhs, lits, coeffs, result);
return result;
}
private void generateConstraint(final int rhs, final LNGVector lits, final LNGIntVector coeffs,
final List result) {
final int n = lits.size();
final LNGVector> seqAuxiliary = new LNGVector<>(n + 1);
for (int i = 0; i < n + 1; i++) {
final LNGVector temp = new LNGVector<>();
temp.growTo(rhs + 1);
seqAuxiliary.push(temp);
}
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= rhs; ++j) {
seqAuxiliary.get(i).set(j, this.f.newPBVariable());
}
}
for (int i = 1; i <= n; i++) {
final int wi = coeffs.get(i - 1);
assert wi <= rhs;
for (int j = 1; j <= rhs; j++) {
if (i >= 2 && i <= n && j <= rhs) {
result.add(this.f.clause(seqAuxiliary.get(i - 1).get(j).negate(), seqAuxiliary.get(i).get(j)));
}
if (i <= n && j <= wi) {
result.add(this.f.clause(lits.get(i - 1).negate(), seqAuxiliary.get(i).get(j)));
}
if (i >= 2 && i <= n && j <= rhs - wi) {
result.add(this.f.clause(seqAuxiliary.get(i - 1).get(j).negate(), lits.get(i - 1).negate(), seqAuxiliary.get(i).get(j + wi)));
}
}
if (i >= 2) {
result.add(this.f.clause(seqAuxiliary.get(i - 1).get(rhs + 1 - wi).negate(), lits.get(i - 1).negate()));
}
}
}
@Override
public String toString() {
return this.getClass().getSimpleName();
}
}