diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
index 555f07d..fcd5ccc 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() {
@@ -205,7 +237,7 @@
 				return children[0] + ".equals(" + children[1] + ")";
 			}
 			return "(" + children[0] + "==" + children[1] + ")";
-		}		
+		}
 	}, new Symbol.ICalculator() {
 		@Override
 		public Expression calculate(List<Expression> args) {
@@ -220,6 +252,13 @@
 			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)) {
@@ -263,6 +302,13 @@
 			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 +341,13 @@
 			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 +378,13 @@
 			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 +415,13 @@
 			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 +452,13 @@
 			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 +489,7 @@
 			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 +514,7 @@
 			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 +534,7 @@
 			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