Help SSGA expansion by adding more beliefs from full expansion

The SSGA expansion got stuck on beliefs from expansion using the greedy
policy multiple times. To aid exploration of the belief space, the
expansion is initialized with a few beliefs from the full expansions for
the initial time steps

Protos/src/thinclab/belief/SSGABeliefExpansion.java

@@ -65,12 +65,20 @@ public SSGABeliefExpansion(POMDP p, int maxDepth, int iterations) {
 		this.allPossibleObs = this.p.getAllPossibleObservations();
 		this.nIterations = iterations;
 
-		/* add initial beliefs from the POMDP */
+		/* 
+		 * Run a full belief expansion for 3 time steps to facilitate proper exploration
+		 */
+
+		FullBeliefExpansion fb = new FullBeliefExpansion(this.p, 3);
+		fb.expand();
+
 		this.initialBeliefs = new ArrayList<DD>();
 		this.initialBeliefs.addAll(this.p.getInitialBeliefs());
 
 		this.exploredBeliefs = new HashSet<DD>();
-		this.exploredBeliefs.addAll(this.p.getInitialBeliefs());
+		this.exploredBeliefs.addAll(fb.getBeliefPoints());
+
+		fb = null;
 
 		logger.debug("SSGA expansion search initialized");
 	}

Protos/src/thinclab/tests/TestBeliefExpansionStartegies.java

@@ -95,7 +95,7 @@ void testSSGABeliefExpansion() {
 
 		LOGGER.info("Testing initial beliefs");
 		List<DD> beliefs0 = ssgaBE.getBeliefPoints();
-		assertTrue(beliefs0.size() == this.pomdp.getInitialBeliefs().size());
+		assertTrue(beliefs0.size() >= this.pomdp.getInitialBeliefs().size());
 
 		LOGGER.info("Testing policy based expansion");
 		LOGGER.info("computing policy...");