Implemented agent which chooses to play winning, losing or random moves by solving a simplified MDP model of the game using policy iteration.

Portions of MDP/solver code by Ciaran O'Reilly and Ravi Mohan used under MIT license.

test/aima/core/probability/mdp/ValueIterationTest.java

@@ -0,0 +1,64 @@
+package aima.core.probability.mdp;
+
+import java.util.Map;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import aima.core.environment.cellworld.Cell;
+import aima.core.environment.cellworld.CellWorld;
+import aima.core.environment.cellworld.CellWorldAction;
+import aima.core.environment.cellworld.CellWorldFactory;
+import aima.core.probability.example.MDPFactory;
+import aima.core.probability.mdp.MarkovDecisionProcess;
+import aima.core.probability.mdp.search.ValueIteration;
+
+/**
+ * @author Ravi Mohan
+ * @author Ciaran O'Reilly
+ * 
+ */
+public class ValueIterationTest {
+	public static final double DELTA_THRESHOLD = 1e-3;
+
+	private CellWorld<Double> cw = null;
+	private MarkovDecisionProcess<Cell<Double>, CellWorldAction> mdp = null;
+	private ValueIteration<Cell<Double>, CellWorldAction> vi = null;
+
+	@Before
+	public void setUp() {
+		cw = CellWorldFactory.createCellWorldForFig17_1();
+		mdp = MDPFactory.createMDPForFigure17_3(cw);
+		vi = new ValueIteration<Cell<Double>, CellWorldAction>(1.0);
+	}
+
+	@Test
+	public void testValueIterationForFig17_3() {
+		Map<Cell<Double>, Double> U = vi.valueIteration(mdp, 0.0001);
+
+		Assert.assertEquals(0.705, U.get(cw.getCellAt(1, 1)), DELTA_THRESHOLD);
+		Assert.assertEquals(0.762, U.get(cw.getCellAt(1, 2)), DELTA_THRESHOLD);
+		Assert.assertEquals(0.812, U.get(cw.getCellAt(1, 3)), DELTA_THRESHOLD);
+
+		Assert.assertEquals(0.655, U.get(cw.getCellAt(2, 1)), DELTA_THRESHOLD);
+		Assert.assertEquals(0.868, U.get(cw.getCellAt(2, 3)), DELTA_THRESHOLD);
+
+		Assert.assertEquals(0.611, U.get(cw.getCellAt(3, 1)), DELTA_THRESHOLD);
+		Assert.assertEquals(0.660, U.get(cw.getCellAt(3, 2)), DELTA_THRESHOLD);
+		Assert.assertEquals(0.918, U.get(cw.getCellAt(3, 3)), DELTA_THRESHOLD);
+
+		Assert.assertEquals(0.388, U.get(cw.getCellAt(4, 1)), DELTA_THRESHOLD);
+		Assert.assertEquals(-1.0, U.get(cw.getCellAt(4, 2)), DELTA_THRESHOLD);
+		Assert.assertEquals(1.0, U.get(cw.getCellAt(4, 3)), DELTA_THRESHOLD);
+		
+		for (int j = 3; j >= 1; j--) {
+			StringBuilder sb = new StringBuilder();
+			for (int i = 1; i <= 4; i++) {
+				sb.append(U.get(cw.getCellAt(i, j)));
+				sb.append(" ");
+			}
+			System.out.println(sb.toString());
+		}
+	}
+}