diff --git a/src/main/scala/hb/dhbw/FiniteClosure.scala b/src/main/scala/hb/dhbw/FiniteClosure.scala
index 519a6bb..c3411b9 100644
--- a/src/main/scala/hb/dhbw/FiniteClosure.scala
+++ b/src/main/scala/hb/dhbw/FiniteClosure.scala
@@ -1,9 +1,8 @@
 package hb.dhbw
 
-trait FJNamedType{
-  def name: String
-  def params: List[FJNamedType]
-}
+sealed case class FJType()
+sealed case class FJNamedType(name: String, params: List[FJType]) extends FJType
+sealed case class FJTypeVariable(name: String) extends FJType
 
 class FiniteClosure(val extendsRelations : Set[(FJNamedType, FJNamedType)]){
 
@@ -17,13 +16,13 @@ class FiniteClosure(val extendsRelations : Set[(FJNamedType, FJNamedType)]){
     rel.map(_._2)
   }
   private def reflexiveTypes(of: Set[(FJNamedType, FJNamedType)]) ={
-    val ref = Set.newBuilder[(UnifyRefType, UnifyRefType)]
+    val ref = Set.newBuilder[(FJNamedType, FJNamedType)]
     ref ++= of.map(pair => (pair._1, pair._1))
     ref ++= of.map(pair => (pair._2, pair._2))
     ref.result()
   }
   private def transitiveTypes(of: Set[(FJNamedType, FJNamedType)]) ={
-    val ref = Set.newBuilder[(UnifyRefType, UnifyRefType)]
+    val ref = Set.newBuilder[(FJNamedType, FJNamedType)]
     ref ++= of.flatMap(pair => of.filter(p =>  p._1.eq(pair._2)))
     ref.result()
   }
@@ -31,16 +30,21 @@ class FiniteClosure(val extendsRelations : Set[(FJNamedType, FJNamedType)]){
     val extendsRelation = extendsRelations.filter(pair => pair._1.name.equals(of.name))
     extendsRelation.map(p => {
       val paramMap = p._1.params.zip(of.params).toMap
-      (of,UnifyRefType(p._2.name, p._2.params.map(paramMap)))
+      (of,FJNamedType(p._2.name, p._2.params.map(paramMap)))
     })
   }
   private def superClassTypes(of: Set[(FJNamedType, FJNamedType)]) : Set[(FJNamedType, FJNamedType)] ={
-    val sClass = Set.newBuilder[(UnifyRefType, UnifyRefType)]
+    val sClass = Set.newBuilder[(FJNamedType, FJNamedType)]
     sClass ++= of.flatMap(pair => Set(pair._2, pair._1)).flatMap(t => superClassTypes(t))
     sClass.result()
   }
 
-  def superTypes(of : UnifyRefType) : Set[UnifyRefType] = calculateSupertypes(of)
+  private def convert(unifyType: UnifyType): FJType = unifyType match {
+    case UnifyRefType(n, p) => FJNamedType(n, p.map(convert(_)))
+    case UnifyTV(n) => FJTypeVariable(n)
+  }
+
+  def superTypes(of : UnifyRefType) : Set[UnifyRefType] = calculateSupertypes(convert(of).asInstanceOf[FJNamedType])
 
   def isPossibleSupertype(of: String, superType: String): Boolean = {
     val extendsMap = extendsRelations.map(p => (p._1.name,p._2.name)).toMap