Add a new static ordering to facilitate the study of the solver

behavior.

org.sat4j.core/src/main/java/org/sat4j/minisat/orders/NaturalStaticOrder.java

+/*******************************************************************************
+ * SAT4J: a SATisfiability library for Java Copyright (C) 2004, 2012 Artois University and CNRS
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ *  http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU Lesser General Public License Version 2.1 or later (the
+ * "LGPL"), in which case the provisions of the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of the LGPL, and not to allow others to use your version of
+ * this file under the terms of the EPL, indicate your decision by deleting
+ * the provisions above and replace them with the notice and other provisions
+ * required by the LGPL. If you do not delete the provisions above, a recipient
+ * may use your version of this file under the terms of the EPL or the LGPL.
+ *
+ * Based on the original MiniSat specification from:
+ *
+ * An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
+ * Sixth International Conference on Theory and Applications of Satisfiability
+ * Testing, LNCS 2919, pp 502-518, 2003.
+ *
+ * See www.minisat.se for the original solver in C++.
+ *
+ * Contributors:
+ *   CRIL - initial API and implementation
+ *******************************************************************************/
+package org.sat4j.minisat.orders;
+
+import java.io.PrintWriter;
+
+import org.sat4j.core.LiteralsUtils;
+import org.sat4j.minisat.core.ILits;
+import org.sat4j.minisat.core.IOrder;
+import org.sat4j.minisat.core.IPhaseSelectionStrategy;
+
+/**
+ * Static ordering of the decisions based on the natural order of the variables.
+ * 
+ * It is not meant to be efficient but to allow to easily study the behavior of
+ * the solver on a known order of the decisions.
+ * 
+ * @author leberre
+ *
+ */
+public class NaturalStaticOrder implements IOrder {
+
+    private ILits voc;
+
+    private IPhaseSelectionStrategy phaseSelectionStrategy = new NegativeLiteralSelectionStrategy();
+
+    int index;
+
+    @Override
+    public void setLits(ILits lits) {
+        this.voc = lits;
+    }
+
+    @Override
+    public int select() {
+        while (!voc.isUnassigned(LiteralsUtils.posLit(index))) {
+            index++;
+        }
+        return phaseSelectionStrategy.select(index);
+    }
+
+    @Override
+    public void undo(int x) {
+        index = Math.min(index, LiteralsUtils.var(x));
+    }
+
+    @Override
+    public void updateVar(int p) {
+    }
+
+    @Override
+    public void init() {
+        index = 1;
+    }
+
+    @Override
+    public void printStat(PrintWriter out, String prefix) {
+    }
+
+    @Override
+    public void setVarDecay(double d) {
+    }
+
+    @Override
+    public void varDecayActivity() {
+    }
+
+    @Override
+    public double varActivity(int p) {
+        return 0.0d;
+    }
+
+    @Override
+    public void assignLiteral(int p) {
+    }
+
+    @Override
+    public void setPhaseSelectionStrategy(IPhaseSelectionStrategy strategy) {
+        this.phaseSelectionStrategy = strategy;
+    }
+
+    @Override
+    public IPhaseSelectionStrategy getPhaseSelectionStrategy() {
+        return this.phaseSelectionStrategy;
+    }
+
+    @Override
+    public void updateVarAtDecisionLevel(int q) {
+    }
+
+    @Override
+    public double[] getVariableHeuristics() {
+        return new double[0];
+    }
+
+    @Override
+    public String toString() {
+        return "Natural static ordering";
+    }
+}

org.sat4j.sat/src/main/java/org/sat4j/sat/KTHLauncher.java

@@ -13,6 +13,7 @@ import org.apache.commons.cli.Options;
 import org.apache.commons.cli.ParseException;
 import org.apache.commons.cli.PosixParser;
 import org.sat4j.minisat.learning.MiniSATLearning;
+import org.sat4j.minisat.orders.NaturalStaticOrder;
 import org.sat4j.minisat.orders.VarOrderHeap;
 import org.sat4j.pb.IPBSolver;
 import org.sat4j.pb.OptToPBSATAdapter;
@@ -70,6 +71,8 @@ public class KTHLauncher {
                 "Output the search as a dot file");
         options.addOption("detect", "detect-cards", true,
                 "Detect cardinality constraints from original constraints. Legal value are never, preproc, inproc, lazy.");
+        options.addOption("natural", "natural-static-order", false,
+                "Use a static order for decisions, using the natural order of the variables, from 1 to n.");
         Option op = options.getOption("coeflim");
         op.setArgName("limit");
         op = options.getOption("coeflim-small");
@@ -289,6 +292,9 @@ public class KTHLauncher {
                     return;
                 }
             }
+            if (line.hasOption("natural")) {
+                cpsolver.setOrder(new NaturalStaticOrder());
+            }
             System.out.println(pbsolver.toString("c "));
             String[] leftArgs = line.getArgs();
             if (leftArgs.length == 0) {