fix the bug of MHSampler.

example/hurricane2.blog

@@ -0,0 +1,32 @@
+/**
+ * Hurricane 
+ * Figure 4.2 in Milch's thesis
+ */
+
+type City;
+type PrepLevel;
+type DamageLevel;
+
+random City First ~ UniformChoice({c for City c});
+
+random City NotFirst ~ UniformChoice({c for City c: c != First});
+
+random PrepLevel Prep(City c) ~
+  if (First == c) then Categorical({High -> 0.5, Low -> 0.5})
+  else case Damage(First) in 
+            {Severe -> Categorical({High -> 0.9, Low -> 0.1}),
+                    Mild -> Categorical({High -> 0.1, Low -> 0.9})}
+            ;
+
+random DamageLevel Damage(City c) ~
+   case Prep(c) in {High -> Categorical({Severe -> 0.2, Mild -> 0.8}),
+            Low -> Categorical({Severe -> 0.8, Mild -> 0.2})}
+          ;
+
+distinct City A, B;
+distinct PrepLevel Low, High;
+distinct DamageLevel Severe, Mild;
+
+obs Damage(First) = Severe;
+
+query First;

src/main/java/blog/sample/GenericProposer.java

@@ -37,11 +37,12 @@
 
 import java.util.HashSet;
 import java.util.Iterator;
-import java.util.LinkedList;
 import java.util.Properties;
 import java.util.Set;
 
+import blog.bn.BasicVar;
 import blog.bn.BayesNetVar;
+import blog.bn.DerivedVar;
 import blog.bn.VarWithDistrib;
 import blog.common.Util;
 import blog.distrib.CondProbDistrib;
@@ -147,46 +148,91 @@ public double proposeNextState(PartialWorldDiff world) {
       System.out.println(world);
     }
 
-    // Remove barren variables
-    LinkedList newlyBarren = new LinkedList(world.getNewlyBarrenVars());
-    while (!newlyBarren.isEmpty()) {
-      BayesNetVar var = (BayesNetVar) newlyBarren.removeFirst();
-      if (!evidenceVars.contains(var) && !queryVars.contains(var)) {
-
-        // Remember its parents.
-        Set parentSet = world.getCBN().getParents(var);
-
-        if (var instanceof VarWithDistrib) {
-          // Multiply in the probability of sampling this
-          // variable again. Since the parent value may have
-          // changed, must use the old world.
-          logProbBackward += world.getSaved().getLogProbOfValue(var);
-
-          // Uninstantiate
-          world.setValue((VarWithDistrib) var, null);
+    // Remove unnecessary variables
+
+    Set evidenceAndQueries = new HashSet();
+    for (Iterator iter = evidenceVars.iterator(); iter.hasNext();) {
+      BayesNetVar var = (BayesNetVar) iter.next();
+      if (var instanceof BasicVar) {
+        evidenceAndQueries.add(var);
+      } else if (var instanceof DerivedVar) {
+        TraceParentRecEvalContext context = new TraceParentRecEvalContext(
+            new PartialWorldDiff(world));
+        var.ensureDetAndSupported(context);
+        if (context.getDependentVar() != null) {
+          evidenceAndQueries.addAll(context.getDependentVar());
         }
-
-        // Check to see if its parents are now barren.
-        for (Iterator parentIter = parentSet.iterator(); parentIter.hasNext();) {
-
-          // If parent is barren, add to the end of this
-          // linked list. Note that if a parent has two
-          // barren children, it will only be added to the
-          // end of the list once, when the last child is
-          // considered.
-          BayesNetVar parent = (BayesNetVar) parentIter.next();
-          if (world.getCBN().getChildren(parent).isEmpty())
-            newlyBarren.addLast(parent);
+      }
+    }
+    for (Iterator iter = queryVars.iterator(); iter.hasNext();) {
+      BayesNetVar var = (BayesNetVar) iter.next();
+      if (var instanceof BasicVar) {
+        evidenceAndQueries.add(var);
+      } else if (var instanceof DerivedVar) {
+        TraceParentRecEvalContext context = new TraceParentRecEvalContext(
+            new PartialWorldDiff(world));
+        var.ensureDetAndSupported(context);
+        if (context.getDependentVar() != null) {
+          evidenceAndQueries.addAll(context.getDependentVar());
         }
       }
     }
-
-    // Uniform sampling from new world.
+    boolean OK;
+    do {
+      OK = true;
+      for (Iterator iter = world.getInstantiatedVars().iterator(); iter
+          .hasNext();) {
+        BasicVar var = (BasicVar) iter.next();
+        Object value = world.getValue(var);
+        world.setValue(var, null);
+        if (!evidenceAndQueriesSupported(evidenceAndQueries, world)) {
+          world.setValue(var, value);
+        } else {
+          OK = false;
+          logProbBackward += world.getSaved().getLogProbOfValue(var);
+        }
+      }
+    } while (!OK);
     logProbBackward += (-Math.log(world.getInstantiatedVars().size()
         - numBasicEvidenceVars));
     return (logProbBackward - logProbForward);
   }
 
+  protected boolean evidenceAndQueriesSupported(Set evidenceAndQueries,
+      PartialWorld world) {
+    PartialWorldDiff tmpWorld = new PartialWorldDiff(world);
+    for (Iterator iter = evidenceAndQueries.iterator(); iter.hasNext();) {
+      BasicVar var = (BasicVar) iter.next();
+      if (!tmpWorld.isInstantiated(var)) {
+        return false;
+      }
+      TraceParentRecEvalContext context = new TraceParentRecEvalContext(
+          tmpWorld);
+      if (var instanceof VarWithDistrib) {
+        ((VarWithDistrib) var).getDistrib(context);
+        if (context.getNumCalculateNewVars() > 0) {
+          return false;
+        }
+      }
+    }
+    for (Iterator iter = tmpWorld.getInstantiatedVars().iterator(); iter
+        .hasNext();) {
+      BasicVar var = (BasicVar) iter.next();
+      if (!tmpWorld.isInstantiated(var)) {
+        return false;
+      }
+      TraceParentRecEvalContext context = new TraceParentRecEvalContext(
+          tmpWorld);
+      if (var instanceof VarWithDistrib) {
+        ((VarWithDistrib) var).getDistrib(context);
+        if (context.getNumCalculateNewVars() > 0) {
+          return false;
+        }
+      }
+    }
+    return true;
+  }
+
   // Samples a new value for the given variable (which must be
   // supported in <code>world</code>) and sets this new value as the
   // value of the variable in <code>world</code>. Then ensures that
@@ -195,7 +241,10 @@ public double proposeNextState(PartialWorldDiff world) {
   // updates the logProbForward and logProbBackward variables.
   protected void sampleValue(VarWithDistrib varToSample, PartialWorld world) {
     // Save child set before graph becomes out of date
-    Set children = world.getCBN().getChildren(varToSample);
+    Set children = new HashSet();
+    children.addAll(world.getCBN().getChildren(varToSample));
+    children.addAll(evidenceVars);
+    children.addAll(queryVars);
 
     DependencyModel.Distrib distrib = varToSample
         .getDistrib(new DefaultEvalContext(world, true));
@@ -217,9 +266,10 @@ protected void sampleValue(VarWithDistrib varToSample, PartialWorld world) {
 
     for (Iterator childrenIter = children.iterator(); childrenIter.hasNext();) {
       BayesNetVar child = (BayesNetVar) childrenIter.next();
-      if (!world.isInstantiated(child)) // NOT SURE YET THIS IS THE RIGHT THING
-                                        // TO DO! CHECKING WITH BRIAN.
-        continue;
+      // if (!world.isInstantiated(child)) // NOT SURE YET THIS IS THE RIGHT
+      // THING
+      // TO DO! CHECKING WITH BRIAN.
+      // continue;
       child.ensureDetAndSupported(instantiator);
     }
 
@@ -251,6 +301,5 @@ public double latestLogProbBackward() {
   public double latestLogProbForward() {
     return logProbForward;
   }
-
   // End of debugger-only members.
 }

src/main/java/blog/sample/ParentRecEvalContext.java

@@ -35,7 +35,9 @@
 
 package blog.sample;
 
-import java.util.*;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Set;
 
 import blog.ObjectIdentifier;
 import blog.bn.BasicVar;
@@ -53,80 +55,80 @@
  * {@link #getOrComputeValue(BasicVar)} instead.
  */
 public class ParentRecEvalContext extends DefaultEvalContext {
-	/**
-	 * Creates a new ParentRecEvalContext using the given world.
-	 */
-	public ParentRecEvalContext(PartialWorld world) {
-		super(world);
-	}
+  /**
+   * Creates a new ParentRecEvalContext using the given world.
+   */
+  public ParentRecEvalContext(PartialWorld world) {
+    super(world);
+  }
 
-	/**
-	 * Creates a new ParentRecEvalContext using the given world. If the
-	 * <code>errorIfUndet</code> flag is true, the access methods on this instance
-	 * will print error messages and exit the program if the world is not complete
-	 * enough to determine the correct return value. Otherwise they will just
-	 * return null in such cases.
-	 */
-	public ParentRecEvalContext(PartialWorld world, boolean errorIfUndet) {
-		super(world, errorIfUndet);
-	}
+  /**
+   * Creates a new ParentRecEvalContext using the given world. If the
+   * <code>errorIfUndet</code> flag is true, the access methods on this instance
+   * will print error messages and exit the program if the world is not complete
+   * enough to determine the correct return value. Otherwise they will just
+   * return null in such cases.
+   */
+  public ParentRecEvalContext(PartialWorld world, boolean errorIfUndet) {
+    super(world, errorIfUndet);
+  }
 
-	final public Object getValue(BasicVar var) {
-		Object value = getOrComputeValue(var);
-		if (value == null) {
-			latestUninstParent = var;
-			var.ensureStable();
-			handleMissingVar(var);
-		} else {
-			if (parents.add(var)) {
-				var.ensureStable();
-			}
-		}
-		return value;
-	}
+  public Object getValue(BasicVar var) {
+    Object value = getOrComputeValue(var);
+    if (value == null) {
+      latestUninstParent = var;
+      var.ensureStable();
+      handleMissingVar(var);
+    } else {
+      if (parents.add(var)) {
+        var.ensureStable();
+      }
+    }
+    return value;
+  }
 
-	protected Object getOrComputeValue(BasicVar var) {
-		return world.getValue(var);
-	}
+  protected Object getOrComputeValue(BasicVar var) {
+    return world.getValue(var);
+  }
 
-	// Note that we don't have to override getSatisfiers, because the
-	// DefaultEvalContext implementation of getSatisfiers calls getValue
-	// on the number variable
+  // Note that we don't have to override getSatisfiers, because the
+  // DefaultEvalContext implementation of getSatisfiers calls getValue
+  // on the number variable
 
-	public NumberVar getPOPAppSatisfied(Object obj) {
-		if (obj instanceof NonGuaranteedObject) {
-			return ((NonGuaranteedObject) obj).getNumberVar();
-		}
+  public NumberVar getPOPAppSatisfied(Object obj) {
+    if (obj instanceof NonGuaranteedObject) {
+      return ((NonGuaranteedObject) obj).getNumberVar();
+    }
 
-		if (obj instanceof ObjectIdentifier) {
-			parents.add(new OriginVar((ObjectIdentifier) obj));
-			return world.getPOPAppSatisfied(obj);
-		}
+    if (obj instanceof ObjectIdentifier) {
+      parents.add(new OriginVar((ObjectIdentifier) obj));
+      return world.getPOPAppSatisfied(obj);
+    }
 
-		// Must be guaranteed object, so not generated by any number var
-		return null;
-	}
+    // Must be guaranteed object, so not generated by any number var
+    return null;
+  }
 
-	/**
-	 * Returns the set of basic random variables that are instantiated and whose
-	 * values have been used in calls to the access methods. This set is backed by
-	 * the ParentRecEvalContext and will change as more random variables are used.
-	 * 
-	 * @return unmodifiable Set of BasicVar
-	 */
-	public Set getParents() {
-		return Collections.unmodifiableSet(parents);
-	}
+  /**
+   * Returns the set of basic random variables that are instantiated and whose
+   * values have been used in calls to the access methods. This set is backed by
+   * the ParentRecEvalContext and will change as more random variables are used.
+   * 
+   * @return unmodifiable Set of BasicVar
+   */
+  public Set getParents() {
+    return Collections.unmodifiableSet(parents);
+  }
 
-	/**
-	 * Returns the variable whose value was most recently needed by an access
-	 * method, but which is not instantiated. This method returns null if no such
-	 * variable exists.
-	 */
-	public BasicVar getLatestUninstParent() {
-		return latestUninstParent;
-	}
+  /**
+   * Returns the variable whose value was most recently needed by an access
+   * method, but which is not instantiated. This method returns null if no such
+   * variable exists.
+   */
+  public BasicVar getLatestUninstParent() {
+    return latestUninstParent;
+  }
 
-	protected Set parents = new LinkedHashSet(); // of BasicVar
-	protected BasicVar latestUninstParent = null;
+  protected Set parents = new LinkedHashSet(); // of BasicVar
+  protected BasicVar latestUninstParent = null;
 }