diff --git a/AlgebraicDataflowArchitectureModel/models/NemophilaAccounts.model b/AlgebraicDataflowArchitectureModel/models/NemophilaAccounts.model
index c2cc23a..0158d26 100644
--- a/AlgebraicDataflowArchitectureModel/models/NemophilaAccounts.model
+++ b/AlgebraicDataflowArchitectureModel/models/NemophilaAccounts.model
@@ -36,7 +36,7 @@
 	out accounts.{sendId}.requesting(sendRequesting:Map, sync1(recvId:Str, sendRequested:Map, recvRequesting:Map, sendFriends:Map)) = if(contains(sendFriends:Map, recvId) == true,
 																																		sendRequesting,
 																																		insert(sendRequesting:Map, recvId:Str, true))
-	out accounts.{recvId}.requested(recvRequested:Map, sync1(recvId:Str, sendRequested:Map, recvRequesting:Map, sendFriends:Map)) = if(ontains(sendFriends:Map, recvId) == true,
+	out accounts.{recvId}.requested(recvRequested:Map, sync1(recvId:Str, sendRequested:Map, recvRequesting:Map, sendFriends:Map)) = if(contains(sendFriends:Map, recvId) == true,
 																																		recvRequested,
 																																		insert(recvRequested:Map, sendId:Str, true))
 }
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
index 51abab3..2586162 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
@@ -262,7 +262,7 @@
 										((Variable) param).setType(var.getType());
 									}
 								}
-								params.add(param.toImplementation(null));
+								params.add(param.toImplementation(new String[] {""}));
 							} else {
 								params.add(var.getName());
 							}
@@ -1496,7 +1496,7 @@
 							}
 							resExp = ((Term) resExp).getChild(0);
 						}
-						String resourceAccess = resExp.toImplementation(new String[] {null});
+						String resourceAccess = resExp.toImplementation(new String[] {""});
 						// Values of channel parameters.
 						for (Selector selector: ch.getAllSelectors()) {
 							if (selector.getExpression() instanceof Variable) {
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
index 59de1bd..c56d194 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
@@ -216,7 +216,7 @@
 												}
 												v++;
 											}
-											String ifStatement = "if (" + conditions.toImplementation(new String[] {})+ ") {\n";
+											String ifStatement = "if (" + conditions.toImplementation(new String[] {""})+ ") {\n";
 											update.addFirstStatement(ifStatement + "\t" + updateStatement.replace("\n", "\n\t") + "\n}");
 										}
 									}
@@ -632,7 +632,7 @@
 											composerSub = composer;
 										}
 										composer.setType(stateGetter.getReturnType());
-										String[] sideEffects = new String[] {null};
+										String[] sideEffects = new String[] {""};
 										String returnValue = composer.toImplementation(sideEffects);
 										if (sideEffects[0] != null) {
 											stateGetter.addStatement(sideEffects[0] + "return " + returnValue+ ";");
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
index 47f4e58..65d2dd7 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
@@ -237,7 +237,7 @@
 												}
 												v++;
 											}
-											String ifStatement = "if (" + conditions.toImplementation(new String[] {})+ ") {\n";
+											String ifStatement = "if (" + conditions.toImplementation(new String[] {""})+ ") {\n";
 											update.addFirstStatement(ifStatement + "\t" + updateStatement.replace("\n", "\n\t") + "\n}");
 										}
 									}
@@ -281,7 +281,7 @@
 												}
 												resExp = ((Term) resExp).getChild(0);
 											}
-											String resourceAccess = resExp.toImplementation(new String[] {null});
+											String resourceAccess = resExp.toImplementation(new String[] {""});
 											int v = 0;
 											for (VariableDeclaration var: update2.getParameters()) {
 												if (v < out.getResource().getPathParams().size()) {
@@ -977,7 +977,7 @@
 										}
 										resExp = ((Term) resExp).getChild(0);
 									}
-									String resourceAccess = resExp.toImplementation(new String[] {null});
+									String resourceAccess = resExp.toImplementation(new String[] {""});
 									// Values of channel parameters.
 									for (Selector selector: ch.getAllSelectors()) {
 										if (selector.getExpression() instanceof Variable) {
diff --git a/AlgebraicDataflowArchitectureModel/src/models/algebra/Field.java b/AlgebraicDataflowArchitectureModel/src/models/algebra/Field.java
index f51b3c4..6702d3f 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/algebra/Field.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/algebra/Field.java
@@ -14,7 +14,8 @@
 	}
 	
 	public Field(String name, Type type) {
-		super(name, type);
+		super(name);
+		symbol.setSignature(new Type[] {type});
 	}
 	
 	public Field(Symbol symbol) {
@@ -22,7 +23,7 @@
 	}
 	
 	public Type getType() {
-		if (symbol.getSignature().length >= 1) {
+		if (symbol.getSignature() != null && symbol.getSignature().length >= 1) {
 			return symbol.getSignature()[0];
 		}
 		return null;
diff --git a/AlgebraicDataflowArchitectureModel/src/models/algebra/Parameter.java b/AlgebraicDataflowArchitectureModel/src/models/algebra/Parameter.java
index 739ab80..ab84998 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/algebra/Parameter.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/algebra/Parameter.java
@@ -12,7 +12,8 @@
 	}
 	
 	public Parameter(String name, Type type) {
-		super(name, type);
+		super(name);
+		symbol.setSignature(new Type[] {type});
 	}
 	
 	public Parameter(Symbol symbol) {
@@ -20,7 +21,7 @@
 	}
 	
 	public Type getType() {
-		if (symbol.getSignature().length >= 1) {
+		if (symbol.getSignature() != null && symbol.getSignature().length >= 1) {
 			return symbol.getSignature()[0];
 		}
 		return null;
diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
index 555f07d..3a3de81 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
@@ -67,16 +67,22 @@
 			Constant arg1 = (Constant) args.get(1);
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
-			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+			if (arg0.getType() != null && arg1.getType() != null) {
+				if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+					return new Constant(Double.toString(Double.parseDouble(sArg0) + Double.parseDouble(sArg1)), typeDouble);
+				} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
+					return new Constant(Float.toString(Float.parseFloat(sArg0) + Float.parseFloat(sArg1)), typeFloat);
+				} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
+					return new Constant(Long.toString(Long.parseLong(sArg0) + Long.parseLong(sArg1)), typeLong);
+				} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+					return new Constant(Integer.toString(Integer.parseInt(sArg0) + Integer.parseInt(sArg1)), typeInt);
+				}
+			}
+			if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
 				return new Constant(Double.toString(Double.parseDouble(sArg0) + Double.parseDouble(sArg1)), typeDouble);
-			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
-				return new Constant(Float.toString(Float.parseFloat(sArg0) + Float.parseFloat(sArg1)), typeFloat);
-			} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
-				return new Constant(Long.toString(Long.parseLong(sArg0) + Long.parseLong(sArg1)), typeLong);
-			} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+			} else {
 				return new Constant(Integer.toString(Integer.parseInt(sArg0) + Integer.parseInt(sArg1)), typeInt);
 			}
-			return new Constant(Integer.toString(Integer.parseInt(sArg0) + Integer.parseInt(sArg1)));
 		}
 	});
 	public static final Symbol mul = new Symbol(Parser.MUL, 2, Symbol.Type.INFIX, new Symbol.ICalculator() {
@@ -92,16 +98,22 @@
 			Constant arg1 = (Constant) args.get(1);
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
-			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+			if (arg0.getType() != null && arg1.getType() != null) {
+				if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+					return new Constant(Double.toString(Double.parseDouble(sArg0) * Double.parseDouble(sArg1)), typeDouble);
+				} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
+					return new Constant(Float.toString(Float.parseFloat(sArg0) * Float.parseFloat(sArg1)), typeFloat);
+				} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
+					return new Constant(Long.toString(Long.parseLong(sArg0) * Long.parseLong(sArg1)), typeLong);
+				} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+					return new Constant(Integer.toString(Integer.parseInt(sArg0) * Integer.parseInt(sArg1)), typeInt);
+				}
+			}
+			if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
 				return new Constant(Double.toString(Double.parseDouble(sArg0) * Double.parseDouble(sArg1)), typeDouble);
-			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
-				return new Constant(Float.toString(Float.parseFloat(sArg0) * Float.parseFloat(sArg1)), typeFloat);
-			} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
-				return new Constant(Long.toString(Long.parseLong(sArg0) * Long.parseLong(sArg1)), typeLong);
-			} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+			} else {
 				return new Constant(Integer.toString(Integer.parseInt(sArg0) * Integer.parseInt(sArg1)), typeInt);
 			}
-			return new Constant(Integer.toString(Integer.parseInt(sArg0) * Integer.parseInt(sArg1)));
 		}
 	});
 	public static final Symbol sub = new Symbol(Parser.SUB, 2, Symbol.Type.INFIX, new Symbol.ICalculator() {
@@ -117,16 +129,22 @@
 			Constant arg1 = (Constant) args.get(1);
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
-			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+			if (arg0.getType() != null && arg1.getType() != null) {
+				if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+					return new Constant(Double.toString(Double.parseDouble(sArg0) - Double.parseDouble(sArg1)), typeDouble);
+				} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
+					return new Constant(Float.toString(Float.parseFloat(sArg0) - Float.parseFloat(sArg1)), typeFloat);
+				} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
+					return new Constant(Long.toString(Long.parseLong(sArg0) - Long.parseLong(sArg1)), typeLong);
+				} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+					return new Constant(Integer.toString(Integer.parseInt(sArg0) - Integer.parseInt(sArg1)), typeInt);
+				}
+			}
+			if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
 				return new Constant(Double.toString(Double.parseDouble(sArg0) - Double.parseDouble(sArg1)), typeDouble);
-			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
-				return new Constant(Float.toString(Float.parseFloat(sArg0) - Float.parseFloat(sArg1)), typeFloat);
-			} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
-				return new Constant(Long.toString(Long.parseLong(sArg0) - Long.parseLong(sArg1)), typeLong);
-			} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+			} else {
 				return new Constant(Integer.toString(Integer.parseInt(sArg0) - Integer.parseInt(sArg1)), typeInt);
 			}
-			return new Constant(Integer.toString(Integer.parseInt(sArg0) - Integer.parseInt(sArg1)));
 		}
 	});
 	public static final Symbol div = new Symbol(Parser.DIV, 2, Symbol.Type.INFIX, new Symbol.ICalculator() {
@@ -142,16 +160,22 @@
 			Constant arg1 = (Constant) args.get(1);
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
-			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+			if (arg0.getType() != null && arg1.getType() != null) {
+				if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
+					return new Constant(Double.toString(Double.parseDouble(sArg0) / Double.parseDouble(sArg1)), typeDouble);
+				} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
+					return new Constant(Float.toString(Float.parseFloat(sArg0) / Float.parseFloat(sArg1)), typeFloat);
+				} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
+					return new Constant(Long.toString(Long.parseLong(sArg0) / Long.parseLong(sArg1)), typeLong);
+				} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+					return new Constant(Integer.toString(Integer.parseInt(sArg0) / Integer.parseInt(sArg1)), typeInt);
+				}
+			}
+			if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
 				return new Constant(Double.toString(Double.parseDouble(sArg0) / Double.parseDouble(sArg1)), typeDouble);
-			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
-				return new Constant(Float.toString(Float.parseFloat(sArg0) / Float.parseFloat(sArg1)), typeFloat);
-			} else if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
-				return new Constant(Long.toString(Long.parseLong(sArg0) / Long.parseLong(sArg1)), typeLong);
-			} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+			} else {
 				return new Constant(Integer.toString(Integer.parseInt(sArg0) / Integer.parseInt(sArg1)), typeInt);
 			}
-			return new Constant(Integer.toString(Integer.parseInt(sArg0) / Integer.parseInt(sArg1)));
 		}
 	});
 	public static final Symbol mod = new Symbol(Parser.MOD, 2, Symbol.Type.INFIX, "%", Symbol.Type.INFIX, new Symbol.ICalculator() {
@@ -167,10 +191,12 @@
 			Constant arg1 = (Constant) args.get(1);
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
-			if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
-				return new Constant(Long.toString(Long.parseLong(sArg0) % Long.parseLong(sArg1)), typeLong);
-			} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
-				return new Constant(Integer.toString(Integer.parseInt(sArg0) % Integer.parseInt(sArg1)), typeInt);
+			if (arg0.getType() != null && arg1.getType() != null) {
+				if (arg0.getType().equals(typeLong) || arg1.getType().equals(typeLong)) {
+					return new Constant(Long.toString(Long.parseLong(sArg0) % Long.parseLong(sArg1)), typeLong);
+				} else if (arg0.getType().equals(typeInt) || arg1.getType().equals(typeInt)) {
+					return new Constant(Integer.toString(Integer.parseInt(sArg0) % Integer.parseInt(sArg1)), typeInt);
+				}
 			}
 			return new Constant(Integer.toString(Integer.parseInt(sArg0) % Integer.parseInt(sArg1)));
 		}
@@ -183,16 +209,22 @@
 			}
 			Constant arg = (Constant) args.get(0);
 			String sArg = arg.getSymbol().toString();
-			if (arg.getType().equals(typeDouble)) {
+			if (arg.getType() != null) {
+				if (arg.getType().equals(typeDouble)) {
+					return new Constant(Double.toString(-Double.parseDouble(sArg)), typeDouble);
+				} else if (arg.getType().equals(typeFloat)) {
+					return new Constant(Float.toString(-Float.parseFloat(sArg)), typeFloat);
+				} else if (arg.getType().equals(typeLong)) {
+					return new Constant(Long.toString(-Long.parseLong(sArg)), typeLong);
+				} else if (arg.getType().equals(typeInt)) {
+					return new Constant(Integer.toString(-Integer.parseInt(sArg)), typeInt);
+				}
+			}
+			if (sArg.contains(Parser.DOT)) {
 				return new Constant(Double.toString(-Double.parseDouble(sArg)), typeDouble);
-			} else if (arg.getType().equals(typeFloat)) {
-				return new Constant(Float.toString(-Float.parseFloat(sArg)), typeFloat);
-			} else if (arg.getType().equals(typeLong)) {
-				return new Constant(Long.toString(-Long.parseLong(sArg)), typeLong);
-			} else if (arg.getType().equals(typeInt)) {
+			} else {
 				return new Constant(Integer.toString(-Integer.parseInt(sArg)), typeInt);
 			}
-			return new Constant(Integer.toString(-Integer.parseInt(sArg)));
 		}
 	});
 	public static final Symbol eq = new Symbol(Parser.EQ, 2, Symbol.Type.INFIX, new Symbol.IImplGenerator() {
@@ -201,11 +233,12 @@
 			for (String s: childrenSideEffects) {
 				sideEffect[0] += s;
 			}
-			if (childrenTypes[0].equals(typeString) && childrenTypes[1].equals(typeString)) {
+			if (childrenTypes[0] != null && childrenTypes[0].equals(typeString) 
+					&& childrenTypes[1] != null && childrenTypes[1].equals(typeString)) {
 				return children[0] + ".equals(" + children[1] + ")";
 			}
 			return "(" + children[0] + "==" + children[1] + ")";
-		}		
+		}
 	}, new Symbol.ICalculator() {
 		@Override
 		public Expression calculate(List<Expression> args) {
@@ -220,6 +253,13 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) {
+				if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
+					result = Double.parseDouble(sArg0) == Double.parseDouble(sArg1);
+				} else {
+					result = Integer.parseInt(sArg0) == Integer.parseInt(sArg1);
+				}
+			}
 			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
 				result = (Double.parseDouble(sArg0) == Double.parseDouble(sArg1));
 			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
@@ -244,7 +284,8 @@
 			for (String s: childrenSideEffects) {
 				sideEffect[0] += s;
 			}
-			if (childrenTypes[0].equals(typeString) && childrenTypes[1].equals(typeString)) {
+			if (childrenTypes[0] != null && childrenTypes[0].equals(typeString) 
+					&& childrenTypes[1] != null && childrenTypes[1].equals(typeString)) {
 				return "!" + children[0] + ".equals(" + children[1] + ")";
 			}
 			return "(" + children[0] + "!=" + children[1] + ")";
@@ -263,6 +304,13 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) {
+				if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
+					result = Double.parseDouble(sArg0) != Double.parseDouble(sArg1);
+				} else {
+					result = Integer.parseInt(sArg0) != Integer.parseInt(sArg1);
+				}
+			}
 			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
 				result = (Double.parseDouble(sArg0) != Double.parseDouble(sArg1));
 			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
@@ -295,6 +343,13 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) {
+				if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
+					result = Double.parseDouble(sArg0) > Double.parseDouble(sArg1);
+				} else {
+					result = Integer.parseInt(sArg0) > Integer.parseInt(sArg1);
+				}
+			}
 			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
 				result = (Double.parseDouble(sArg0) > Double.parseDouble(sArg1));
 			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
@@ -325,6 +380,13 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) {
+				if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
+					result = Double.parseDouble(sArg0) < Double.parseDouble(sArg1);
+				} else {
+					result = Integer.parseInt(sArg0) < Integer.parseInt(sArg1);
+				}
+			}
 			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
 				result = (Double.parseDouble(sArg0) < Double.parseDouble(sArg1));
 			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
@@ -355,6 +417,13 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) {
+				if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
+					result = Double.parseDouble(sArg0) >= Double.parseDouble(sArg1);
+				} else {
+					result = Integer.parseInt(sArg0) >= Integer.parseInt(sArg1);
+				}
+			}
 			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
 				result = (Double.parseDouble(sArg0) >= Double.parseDouble(sArg1));
 			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
@@ -385,6 +454,13 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) {
+				if (sArg0.contains(Parser.DOT) || sArg1.contains(Parser.DOT)) {
+					result = Double.parseDouble(sArg0) <= Double.parseDouble(sArg1);
+				} else {
+					result = Integer.parseInt(sArg0) <= Integer.parseInt(sArg1);
+				}
+			}
 			if (arg0.getType().equals(typeDouble) || arg1.getType().equals(typeDouble)) {
 				result = (Double.parseDouble(sArg0) <= Double.parseDouble(sArg1));
 			} else if (arg0.getType().equals(typeFloat) || arg1.getType().equals(typeFloat)) {
@@ -415,6 +491,7 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) return null;
 			if (arg0.getType().equals(typeBoolean) || arg1.getType().equals(typeBoolean)) {
 				result = (Boolean.parseBoolean(sArg0) && Boolean.parseBoolean(sArg1));
 			}
@@ -439,6 +516,7 @@
 			String sArg0 = arg0.getSymbol().toString();
 			String sArg1 = arg1.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null || arg1.getType() == null) return null;
 			if (arg0.getType().equals(typeBoolean) || arg1.getType().equals(typeBoolean)) {
 				result = (Boolean.parseBoolean(sArg0) || Boolean.parseBoolean(sArg1));
 			}
@@ -458,6 +536,7 @@
 			Constant arg0 = (Constant) args.get(0);
 			String sArg0 = arg0.getSymbol().toString();
 			boolean result = false;
+			if (arg0.getType() == null) return null;
 			if (arg0.getType().equals(typeBoolean)) {
 				result = !Boolean.parseBoolean(sArg0);
 			}
diff --git a/AlgebraicDataflowArchitectureModel/src/simulator/SystemState.java b/AlgebraicDataflowArchitectureModel/src/simulator/SystemState.java
index 90a4546..e078ccb 100644
--- a/AlgebraicDataflowArchitectureModel/src/simulator/SystemState.java
+++ b/AlgebraicDataflowArchitectureModel/src/simulator/SystemState.java
@@ -1,5 +1,5 @@
 package simulator;
-
+ 
 import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -7,7 +7,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-
+ 
 import models.algebra.Constant;
 import models.algebra.Expression;
 import models.algebra.Term;
@@ -25,7 +25,7 @@
 import simulator.states.MapResourceState;
 import simulator.states.PrimitiveResourceState;
 import simulator.states.ResourceState;
-
+ 
 public class SystemState {
 	private Set<Resource> rootResources = new HashSet<>();
 	private Map<DataTransferChannel, ChannelState> channelStates = new HashMap<>();
@@ -70,7 +70,7 @@
 		}
 		return null;
 	}
-
+ 
 	/**
 	 * update the state of a specified resource
 	 * 
@@ -545,7 +545,7 @@
 		}
 		return null;
 	}
-
+ 
 	public Map.Entry<ResourceState, List<ResourceIdentifier>> createResourceState(ResourceIdentifier resourceIdentifier, Variable curResVar, Expression resCurStateVal, Expression resStateValue) {
 		Type resType = resourceIdentifier.getResourceStateType();
 		if (resType == null && resStateValue instanceof Term) {
@@ -1001,13 +1001,18 @@
 								createInfo.getValue().addAll(childInfo.getValue());
 								createInfo = new AbstractMap.SimpleEntry<>(state, createInfo.getValue());
 							}
-						}
-						
+						}						
 					}
 					return createInfo;
 				}
 			}
 		}
+		if (curResVar != null && resCurStateVal != null) {
+			if (resStateValue instanceof Term) {
+				resStateValue = ((Term) resStateValue).substitute(curResVar, resCurStateVal);
+				resStateValue = ((Term) resStateValue).reduce();
+			}
+		}
 		if (resStateValue instanceof Constant) {
 			Resource res = getResource(resourceIdentifier);
 			ResourceState state = null;
@@ -1039,7 +1044,7 @@
 	public void updateChannelState(DataTransferChannel channel, ChannelState channelState) {
 		channelStates.put(channel, channelState);
 	}
-
+ 
 	public List<Event> getEvents() {
 		return events;
 	}
@@ -1047,4 +1052,4 @@
 	public void addEvent(Event event) {
 		events.add(event);
 	}
-}
+}
\ No newline at end of file