diff --git a/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java b/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java
index 827e5e3..846290d 100644
--- a/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java
+++ b/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java
@@ -112,7 +112,11 @@
 	 * @param query The syntax tree as returned by ANTLR
 	 */
 	public PoliqarpPlusTree(String query) {
-		process(query);
+		try {
+			process(query); 
+		} catch (NullPointerException e) {
+			throw new RuntimeException("Error handling query.");
+		}
 		System.out.println(">>> "+requestMap.get("query")+" <<<");
         log.info(">>> " + requestMap.get("query") + " <<<");
 	}
@@ -198,8 +202,6 @@
 		 ****************************************************************
 		 ****************************************************************
 		 */
-		if (nodeCat.equals("query")) {
-		}
 
 		// cq_segments/sq_segments: token group
 		if (nodeCat.equals("cq_segments") || nodeCat.equals("sq_segments")) {
@@ -228,7 +230,7 @@
 							requestMap.put("query", occGroup);
 						} else {
 							// not an only child, need to create containing sequence
-							if (node.getParent().getChild(0).equals(node)) {
+							if (node.getParent().getChild(0) == node) {
 								// if first child, create containing sequence and embed there
 								LinkedHashMap<String,Object> superSequence = new LinkedHashMap<String,Object>();
 								superSequence.put("@type", "korap:sequence");
@@ -240,7 +242,8 @@
 								stackedObjects--;
 							} else {
 								// if not first child, add to previously created parent sequence
-								ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(1).get("operands");
+								// parent sequence is at position 3 because of previously added groups
+								ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(3).get("operands");
 								topSequenceOperands.add(occGroup);
 							}
 						}
@@ -250,61 +253,62 @@
 						ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(1+occExtraChild).get("operands");
 						topSequenceOperands.add(occGroup);
 					}
-				}
-				// Step I: decide type of element (one or more elements? -> token or sequence)
-				// take into account a possible 'occ' child
-				int occExtraChild = cqHasOcc ? 1:0;
-				if (node.getChildCount()>1+occExtraChild) {
-					sequence.put("@type", "korap:sequence");
-					ArrayList<Object> sequenceOperands = new ArrayList<Object>();
-					sequence.put("operands", sequenceOperands);
 				} else {
-					// if only child, make the sequence a mere korap:token...
-					// ... but only if it has a real token/element beneath it
-					if (getNodeCat(node.getChild(0)).equals("cq_segment")
-						|| getNodeCat(node.getChild(0)).equals("element")	) {
-						sequence.put("@type", "korap:token");
-						tokenStack.push(sequence);
-						stackedTokens++;
-					// else, it's a group (with shrink()/spanclass/... as child)
+					// Step I: decide type of element (one or more elements? -> token or sequence)
+					// take into account a possible 'occ' child
+					int occExtraChild = cqHasOcc ? 1:0;
+					if (node.getChildCount()>1+occExtraChild) {
+						sequence.put("@type", "korap:sequence");
+						ArrayList<Object> sequenceOperands = new ArrayList<Object>();
+						sequence.put("operands", sequenceOperands);
 					} else {
-						sequence.put("@type", "korap:group");
-					}
-				}
-				// Step II: decide where to put this element 
-				// check if this is an argument for a containing occurrence group (see step 0)
-				if (cqHasOcc) {
-					ArrayList<Object> topGroupOperands = (ArrayList<Object>) objectStack.get(0).get("operands");
-					topGroupOperands.add(sequence);
-				// ...if not modified by occurrence, put into suitable super structure
-				} else {
-					if (openNodeCats.get(1).equals("query")) {
-						// cq_segment is top query node
-						if (node.getParent().getChildCount()==1) {
-							// only child
-							requestMap.put("query", sequence);
+						// if only child, make the sequence a mere korap:token...
+						// ... but only if it has a real token/element beneath it
+						if (getNodeCat(node.getChild(0)).equals("cq_segment")
+							|| getNodeCat(node.getChild(0)).equals("element")	) {
+							sequence.put("@type", "korap:token");
+							tokenStack.push(sequence);
+							stackedTokens++;
+						// else, it's a group (with shrink()/spanclass/... as child)
 						} else {
-							// not an only child, need to create containing sequence
-							if (node.getParent().getChild(0).equals(node)) {
-								// if first child, create containing sequence and embed there
-								LinkedHashMap<String,Object> superSequence = new LinkedHashMap<String,Object>();
-								superSequence.put("@type", "korap:sequence");
-								ArrayList<Object> operands = new ArrayList<Object>();
-								superSequence.put("operands", operands);
-								operands.add(sequence);
-								requestMap.put("query", superSequence);
-								objectStack.add(1, superSequence); // add at 2nd position to keep current cq_segment accessible
-								stackedObjects--;
-							} else {
-								// if not first child, add to previously created parent sequence
-								ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(1).get("operands");
-								topSequenceOperands.add(sequence);
-							}
+							sequence.put("@type", "korap:group");
 						}
-					} else if (!objectStack.isEmpty()){
-						// embed in super sequence
-						ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(1).get("operands");
-						topSequenceOperands.add(sequence);
+					}
+					// Step II: decide where to put this element 
+					// check if this is an argument for a containing occurrence group (see step 0)
+					if (cqHasOcc) {
+						ArrayList<Object> topGroupOperands = (ArrayList<Object>) objectStack.get(0).get("operands");
+						topGroupOperands.add(sequence);
+					// ...if not modified by occurrence, put into suitable super structure
+					} else {
+						if (openNodeCats.get(1).equals("query")) {
+							// cq_segment is top query node
+							if (node.getParent().getChildCount()==1) {
+								// only child
+								requestMap.put("query", sequence);
+							} else {
+								// not an only child, need to create containing sequence
+								if (node.getParent().getChild(0).equals(node)) {
+									// if first child, create containing sequence and embed there
+									LinkedHashMap<String,Object> superSequence = new LinkedHashMap<String,Object>();
+									superSequence.put("@type", "korap:sequence");
+									ArrayList<Object> operands = new ArrayList<Object>();
+									superSequence.put("operands", operands);
+									operands.add(sequence);
+									requestMap.put("query", superSequence);
+									objectStack.add(1, superSequence); // add at 2nd position to keep current cq_segment accessible
+									stackedObjects--;
+								} else {
+									// if not first child, add to previously created parent sequence
+									ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(1).get("operands");
+									topSequenceOperands.add(sequence);
+								}
+							}
+						} else if (!objectStack.isEmpty()){
+							// embed in super sequence
+							ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(1).get("operands");
+							topSequenceOperands.add(sequence);
+						}
 					}
 				}
 			}
@@ -339,6 +343,24 @@
 				topSequenceOperands.add(token);
 			}
 		}
+		
+		// cq_segment modified by occurrence
+		if (nodeCat.equals("cq_seg_occ")) {
+			LinkedHashMap<String,Object> group = new LinkedHashMap<String,Object>();
+			curOccGroup = group;
+			group.put("@type", "korap:group");
+			group.put("operands", new ArrayList<Object>());
+			objectStack.push(group);
+			stackedObjects++;
+			// add group to sequence only if it is not an only child (in that case, cq_segments has already added the info and is just waiting for the values from "field")
+			// take into account a possible 'occ' child
+			if (node.getParent().getChildCount()>1) {
+				ArrayList<Object> topSequenceOperands = (ArrayList<Object>) objectStack.get(1).get("operands");
+				topSequenceOperands.add(group);
+			} else {
+				requestMap.put("query", group);
+			}
+		}
 
 		// disjoint cq_segments, like ([base=foo][base=bar])|[base=foobar]
 		if (nodeCat.equals("cq_disj_segments")) {
@@ -777,10 +799,16 @@
 		 * For testing
 		 */
 		String[] queries = new String[] {
-				"shrink(startswith(<s>,{<np>}))",
-				"shrink(1: startswith(<s>,{1:<np>}))",
-				"contains(<p>, startswith(<s>,<np>))",
-				"[base=bar][base=foo]*"
+//				"shrink(startswith(<s>,{<np>}))",
+//				"shrink(1: startswith(<s>,{1:<np>}))",
+//				"contains(<p>, startswith(<s>,<np>))",
+//				"[base=foo]*",
+//				"[base=foo]*[base=bar]",
+//				"[base=bar][base=foo]*",
+//				"([base=bar][base=foo])*",
+				"<s>([base=bar][base=foo])*",
+//				"<s><np>([base=bar][base=foo])*"
+				
 				
 		};
 		PoliqarpPlusTree.verbose=true;
diff --git a/src/test/java/PoliqarpPlusTreeTest.java b/src/test/java/PoliqarpPlusTreeTest.java
index de9e493..d865490 100644
--- a/src/test/java/PoliqarpPlusTreeTest.java
+++ b/src/test/java/PoliqarpPlusTreeTest.java
@@ -110,6 +110,91 @@
 		ppt = new PoliqarpPlusTree("[base=bar][base=foo]*");
 		map = ppt.getRequestMap().get("query").toString();
 		assertEquals(occ3.replaceAll(" ", ""), map.replaceAll(" ", ""));
+		
+		// ([base=bar][base=foo])*
+		String occ4 = 
+				"{@type=korap:group, operands=[" +	
+					"{@type=korap:sequence, operands=[" +
+						"{@type=korap:token, @value={@type=korap:term, @value=base:bar, relation==}}," +
+						"{@type=korap:token, @value={@type=korap:term, @value=base:foo, relation==}}" +
+					"]}" +
+				"], relation=repetition, quantifier=* }" ;
+		ppt = new PoliqarpPlusTree("([base=bar][base=foo])*");
+		map = ppt.getRequestMap().get("query").toString();
+		assertEquals(occ4.replaceAll(" ", ""), map.replaceAll(" ", ""));
+		
+		// <s>([base=bar][base=foo])*
+		String occ5 = 
+				"{@type=korap:sequence, operands=[" +
+					"{@type=korap:element, @value=s}," +
+					"{@type=korap:group, operands=[" +	
+						"{@type=korap:sequence, operands=[" +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:bar, relation==}}," +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:foo, relation==}}" +
+						"]}" +
+					"], relation=repetition, quantifier=* }" +
+				"]}" ;
+		ppt = new PoliqarpPlusTree("<s>([base=bar][base=foo])*");
+		map = ppt.getRequestMap().get("query").toString();
+		assertEquals(occ5.replaceAll(" ", ""), map.replaceAll(" ", ""));
+		
+		// <s><np>([base=bar][base=foo])*
+		// comment: embedded sequence shouldn't really be here, but does not really hurt, either. (?)
+		// really hard to get this behaviour out of the PQPlus grammar...
+		String occ6 = 
+				"{@type=korap:sequence, operands=[" +
+					"{@type=korap:sequence, operands=[" +
+						"{@type=korap:element, @value=s}," +
+						"{@type=korap:element, @value=np}" +
+					"]}," +
+					"{@type=korap:group, operands=[" +	
+						"{@type=korap:sequence, operands=[" +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:bar, relation==}}," +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:foo, relation==}}" +
+						"]}" +
+					"], relation=repetition, quantifier=* }" +
+				"]}" ;
+		ppt = new PoliqarpPlusTree("<s><np>([base=bar][base=foo])*");
+		map = ppt.getRequestMap().get("query").toString();
+		assertEquals(occ6.replaceAll(" ", ""), map.replaceAll(" ", ""));
+		
+		// <s><np>([base=bar][base=foo])*[p=NN]
+		// comment: embedded sequence shouldn't really be here, but does not really hurt, either. (?)
+		// really hard to get this behaviour out of the PQPlus grammar...
+		String occ7 = 
+				"{@type=korap:sequence, operands=[" +
+					"{@type=korap:sequence, operands=[" +
+						"{@type=korap:element, @value=s}," +
+						"{@type=korap:element, @value=np}" +
+					"]}," +
+					"{@type=korap:group, operands=[" +	
+						"{@type=korap:sequence, operands=[" +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:bar, relation==}}," +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:foo, relation==}}" +
+						"]}" +
+					"], relation=repetition, quantifier=* }," +
+					"{@type=korap:token, @value={@type=korap:term, @value=p:NN, relation==}}" +
+				"]}" ;
+		ppt = new PoliqarpPlusTree("<s><np>([base=bar][base=foo])*[p=NN]");
+		map = ppt.getRequestMap().get("query").toString();
+		assertEquals(occ7.replaceAll(" ", ""), map.replaceAll(" ", ""));
+		
+		// ([base=bar][base=foo])*[p=NN]
+		// comment: embedded sequence shouldn't really be here, but does not really hurt, either. (?)
+		// really hard to get this behaviour out of the PQPlus grammar...
+		String occ8 = 
+				"{@type=korap:sequence, operands=[" +
+					"{@type=korap:group, operands=[" +	
+						"{@type=korap:sequence, operands=[" +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:bar, relation==}}," +
+							"{@type=korap:token, @value={@type=korap:term, @value=base:foo, relation==}}" +
+						"]}" +
+					"], relation=repetition, quantifier=* }," +
+					"{@type=korap:token, @value={@type=korap:term, @value=p:NN, relation==}}" +
+				"]}" ;
+		ppt = new PoliqarpPlusTree("([base=bar][base=foo])*[p=NN]");
+		map = ppt.getRequestMap().get("query").toString();
+		assertEquals(occ8.replaceAll(" ", ""), map.replaceAll(" ", ""));
 	}
 	
 	@Test