diff --git a/src/de/dhbwstuttgart/core/JavaTXCompiler.java b/src/de/dhbwstuttgart/core/JavaTXCompiler.java
index 68bb2585..05edbaa1 100644
--- a/src/de/dhbwstuttgart/core/JavaTXCompiler.java
+++ b/src/de/dhbwstuttgart/core/JavaTXCompiler.java
@@ -121,8 +121,9 @@ public class JavaTXCompiler {
 				System.out.println(xConsSet);
 				Set<String> paraTypeVarNames = allClasses.stream().map(x -> x.getMethods().stream().map(y -> y.getParameterList().getFormalparalist()
 						.stream().filter(z -> z.getType() instanceof TypePlaceholder)
-						.map(z -> ((TypePlaceholder)z.getType()).getName()).collect(Collectors.toCollection(HashSet::new))).reduce((a,b) -> { a.addAll(b); return a;} ).get())
-						.reduce((a,b) -> { a.addAll(b); return a;} ).get();
+						.map(z -> ((TypePlaceholder)z.getType()).getName()).collect(Collectors.toCollection(HashSet::new)))
+						.reduce(new HashSet<String>(), (a,b) -> { a.addAll(b); return a;}, (a,b) -> { a.addAll(b); return a;} )  )
+						.reduce(new HashSet<String>(), (a,b) -> { a.addAll(b); return a;} );
 				
 				Set<String> returnTypeVarNames = allClasses.stream().map(x -> x.getMethods().stream().filter(y -> y.getReturnType() instanceof TypePlaceholder)
 						.map(z -> ((TypePlaceholder)z.getReturnType()).getName()).collect(Collectors.toCollection(HashSet::new))).reduce((a,b) -> { a.addAll(b); return a;} ).get();
diff --git a/src/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java b/src/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java
index 4dad9de6..c15f65fc 100644
--- a/src/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java
+++ b/src/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java
@@ -217,7 +217,7 @@ public class TYPEStmt implements StatementVisitor{
                 binary.operation.equals(BinaryExpr.Operator.MUL)||
                 binary.operation.equals(BinaryExpr.Operator.MOD)||
                 binary.operation.equals(BinaryExpr.Operator.ADD)){
-            Set<Constraint> numericAdditionOrStringConcatenation = new HashSet<>();
+            Set<Constraint<Pair>> numericAdditionOrStringConcatenation = new HashSet<>();
             
             //Zuerst der Fall für Numerische AusdrücPairOpnumericeratorke, das sind Mul, Mod und Div immer:
             //see: https://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.17
@@ -273,7 +273,7 @@ public class TYPEStmt implements StatementVisitor{
                 binary.operation.equals(BinaryExpr.Operator.BIGGERTHAN) ||
                 binary.operation.equals(BinaryExpr.Operator.LESSTHAN)){
         	//eingefuegt PL 2018-05-24
-        	Set<Constraint> numericRelationConcatenation = new HashSet<>();
+        	Set<Constraint<Pair>> numericRelationConcatenation = new HashSet<>();
         	Constraint<Pair> numeric = new Constraint<>();
         	numeric.add(new Pair(binary.lexpr.getType(), bytee, PairOperator.SMALLERDOT));
             numeric.add(new Pair(binary.rexpr.getType(), bytee, PairOperator.SMALLERDOT));
diff --git a/src/de/dhbwstuttgart/typeinference/unify/TypeUnifyTask.java b/src/de/dhbwstuttgart/typeinference/unify/TypeUnifyTask.java
index 1d5ca564..d3448d49 100644
--- a/src/de/dhbwstuttgart/typeinference/unify/TypeUnifyTask.java
+++ b/src/de/dhbwstuttgart/typeinference/unify/TypeUnifyTask.java
@@ -586,8 +586,13 @@ public class TypeUnifyTask extends RecursiveTask<Set<Set<UnifyPair>>>  {
 	
 
 	protected boolean isUndefinedPairSet(Set<UnifyPair> s) {
+		if (s.size() >= 1 ) {
 			Boolean ret = s.stream().map(x -> x.isUndefinedPair()).reduce(true, (x,y)-> (x && y));
 			return ret;
+		}
+		else { 
+			return false;
+		}
 	}
 	
 	protected boolean isUndefinedPairSetSet(Set<Set<UnifyPair>> s) {
diff --git a/test/bytecode/LambdaTest.java b/test/bytecode/LambdaTest.java
index 12e16829..f29690cb 100644
--- a/test/bytecode/LambdaTest.java
+++ b/test/bytecode/LambdaTest.java
@@ -13,7 +13,7 @@ public class LambdaTest {
 	
 	@Test
 	public void generateBC() throws Exception {
-		path = System.getProperty("user.dir")+"/test/bytecode/javFiles/Lambda2.jav";
+		path = System.getProperty("user.dir")+"/test/bytecode/javFiles/Lambda.jav";
 		fileToTest = new File(path);
 		compiler = new JavaTXCompiler(fileToTest);
 		compiler.generateBytecode();
diff --git a/test/bytecode/javFiles/Plus.jav b/test/bytecode/javFiles/Plus.jav
index 86b4eb36..4d425bf0 100644
--- a/test/bytecode/javFiles/Plus.jav
+++ b/test/bytecode/javFiles/Plus.jav
@@ -1,4 +1,4 @@
-//import java.lang.Integer;
+import java.lang.Integer;
 
 public class Plus {
 	
diff --git a/test/bytecode/javFiles/RelOps.jav b/test/bytecode/javFiles/RelOps.jav
index d75ee2f3..0fdd2cff 100644
--- a/test/bytecode/javFiles/RelOps.jav
+++ b/test/bytecode/javFiles/RelOps.jav
@@ -1,4 +1,5 @@
 import java.lang.Integer;
+import java.lang.Boolean;
 
 public class RelOps {
 	m(a,b){