Backjumping bug fixed.

aimacode · Nov 30, 2021 · 8ea5a88 · 8ea5a88
1 parent 864cdee
commit 8ea5a88
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Showing 4 changed files with 21 additions and 15 deletions.
diff --git a/aima-core/src/main/java/aima/core/search/csp/examples/MapCSP.java b/aima-core/src/main/java/aima/core/search/csp/examples/MapCSP.java
@@ -34,7 +34,8 @@ public class MapCSP extends CSP<Variable, String> {
 	 * Australia, with the colors Red, Green, and Blue.
 	 */
 	public MapCSP() {
-		super(Arrays.asList(NSW, WA, T, NT, Q, SA, V));
+		super(Arrays.asList(NT, SA, V, T, NSW, Q, WA));
+		//super(Arrays.asList(NSW, WA, T, NT, Q, SA, V));
 
 		Domain<String> colors = new Domain<>(RED, GREEN, BLUE);
 		for (Variable var : getVariables())

diff --git a/aima-core/src/main/java/aima/core/search/csp/solver/BackjumpingBacktrackingSolver.java b/aima-core/src/main/java/aima/core/search/csp/solver/BackjumpingBacktrackingSolver.java
@@ -84,10 +84,14 @@ private SolutionOrNogood<VAR, VAL> backtrack(CSP<VAR, VAL> csp, Assignment<VAR,
                 fireStateChanged(csp, assignment, var);
                 if (assignment.isConsistent(csp.getConstraints(var))) {
                     SolutionOrNogood<VAR, VAL> res = backtrack(csp, assignment);
-                    if (res.hasSolution() || !res.nogood.contains(var))
+                    if (res.hasSolution()) {
+                        return res; // solution found!
+                    } else if (!res.nogood.contains(var)) {
+                        assignment.remove(var);
                         return res; // jump back!
-                    else
+                    } else {
                         result.nogood.addAll(res.nogood);
+                    }
                 } else {
                     result.nogood.addAll(findCause(csp, assignment, var));
                 }

diff --git a/aima-core/src/test/java/aima/test/core/unit/search/csp/MapCSPTest.java b/aima-core/src/test/java/aima/test/core/unit/search/csp/MapCSPTest.java
@@ -28,12 +28,12 @@ public void setUp() {
 	public void testBackTrackingSearch() {
 		Optional<Assignment<Variable, String>> results = new FlexibleBacktrackingSolver<Variable, String>().solve(csp);
 		Assert.assertTrue(results.isPresent());
-		Assert.assertEquals(MapCSP.GREEN, results.get().getValue(MapCSP.WA));
+		Assert.assertEquals(MapCSP.BLUE, results.get().getValue(MapCSP.WA));
 		Assert.assertEquals(MapCSP.RED, results.get().getValue(MapCSP.NT));
-		Assert.assertEquals(MapCSP.BLUE, results.get().getValue(MapCSP.SA));
-		Assert.assertEquals(MapCSP.GREEN, results.get().getValue(MapCSP.Q));
+		Assert.assertEquals(MapCSP.GREEN, results.get().getValue(MapCSP.SA));
+		Assert.assertEquals(MapCSP.BLUE, results.get().getValue(MapCSP.Q));
 		Assert.assertEquals(MapCSP.RED, results.get().getValue(MapCSP.NSW));
-		Assert.assertEquals(MapCSP.GREEN, results.get().getValue(MapCSP.V));
+		Assert.assertEquals(MapCSP.BLUE, results.get().getValue(MapCSP.V));
 		Assert.assertEquals(MapCSP.RED, results.get().getValue(MapCSP.T));
 	}
 

diff --git a/aima-gui/src/main/java/aima/gui/fx/applications/search/MapColoringCspApp.java b/aima-gui/src/main/java/aima/gui/fx/applications/search/MapColoringCspApp.java
@@ -85,11 +85,12 @@ protected List<Parameter> createParameters() {
                 "Backtracking + Forward Checking + MRV&DEG",
                 "Backtracking + AC3",
                 "Backtracking + AC3 + MRV&DEG + LCV",
+                "Backtracking + Backjumping",
+                "Backtracking + Backjumping + MRV&DEG",
                 "Min-Conflicts (50)",
                 "Tree-CSP-Solver",
-                "Tree-CSP-Solver with Random Root",
-                "Backtracking + Backjumping",
-                "Backtracking + Backjumping + MRV&DEG");
+                "Tree-CSP-Solver with Random Root"
+                );
         return Arrays.asList(p1, p2);
     }
 
@@ -136,19 +137,19 @@ public void initialize() {
                 strategy = new FlexibleBacktrackingSolver<Variable, String>().setAll();
                 break;
             case 8:
-                strategy = new MinConflictsSolver<>(50);
+                strategy = new BackjumpingBacktrackingSolver<>();
                 break;
             case 9:
-                strategy = new TreeCspSolver<>();
+                strategy = new BackjumpingBacktrackingSolver<Variable, String>().set(CspHeuristics.mrvDeg());
                 break;
             case 10:
-                strategy = new TreeCspSolver<Variable, String>().useRandom(true);
+                strategy = new MinConflictsSolver<>(50);
                 break;
             case 11:
-                strategy = new BackjumpingBacktrackingSolver<>();
+                strategy = new TreeCspSolver<>();
                 break;
             case 12:
-                strategy = new BackjumpingBacktrackingSolver<Variable, String>().set(CspHeuristics.mrvDeg());
+                strategy = new TreeCspSolver<Variable, String>().useRandom(true);
                 break;
         }