diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 8a12d42..44bc23b 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -7,6 +7,7 @@
     <list default="true" id="f5e08808-a5af-4c89-a1ee-21b3bcb9ae3e" name="Changes" comment="fucking hell">
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/main/java/ab1/impl/GRUPPE/NFAImpl.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/main/java/ab1/impl/GRUPPE/NFAImpl.java" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/test/java/ab1/tests/ComplexTests.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/java/ab1/tests/ComplexTests.java" afterDir="false" />
     </list>
     <list id="39d4ccb3-eae9-4ed4-996a-5a13f44678fa" name="Changes by carol" comment="" />
     <option name="SHOW_DIALOG" value="false" />
@@ -17,7 +18,7 @@
   <component name="Git.Settings">
     <option name="RECENT_BRANCH_BY_REPOSITORY">
       <map>
-        <entry key="$PROJECT_DIR$" value="2-playing-around" />
+        <entry key="$PROJECT_DIR$" value="main" />
       </map>
     </option>
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
@@ -49,27 +50,27 @@
     <option name="hideEmptyMiddlePackages" value="true" />
     <option name="showLibraryContents" value="true" />
   </component>
-  <component name="PropertiesComponent">{
-  &quot;keyToString&quot;: {
-    &quot;RunOnceActivity.OpenProjectViewOnStart&quot;: &quot;true&quot;,
-    &quot;RunOnceActivity.ShowReadmeOnStart&quot;: &quot;true&quot;,
-    &quot;WebServerToolWindowFactoryState&quot;: &quot;false&quot;,
-    &quot;full.screen.before.presentation.mode&quot;: &quot;false&quot;,
-    &quot;git-widget-placeholder&quot;: &quot;main&quot;,
-    &quot;ignore.virus.scanning.warn.message&quot;: &quot;true&quot;,
-    &quot;node.js.detected.package.eslint&quot;: &quot;true&quot;,
-    &quot;node.js.detected.package.tslint&quot;: &quot;true&quot;,
-    &quot;node.js.selected.package.eslint&quot;: &quot;(autodetect)&quot;,
-    &quot;node.js.selected.package.tslint&quot;: &quot;(autodetect)&quot;,
-    &quot;nodejs_package_manager_path&quot;: &quot;npm&quot;,
-    &quot;project.structure.last.edited&quot;: &quot;Project&quot;,
-    &quot;project.structure.proportion&quot;: &quot;0.0&quot;,
-    &quot;project.structure.side.proportion&quot;: &quot;0.0&quot;,
-    &quot;settings.editor.selected.configurable&quot;: &quot;preferences.pluginManager&quot;,
-    &quot;vue.rearranger.settings.migration&quot;: &quot;true&quot;
+  <component name="PropertiesComponent"><![CDATA[{
+  "keyToString": {
+    "RunOnceActivity.OpenProjectViewOnStart": "true",
+    "RunOnceActivity.ShowReadmeOnStart": "true",
+    "WebServerToolWindowFactoryState": "false",
+    "full.screen.before.presentation.mode": "false",
+    "git-widget-placeholder": "5-top-skill-issue-raphael",
+    "ignore.virus.scanning.warn.message": "true",
+    "node.js.detected.package.eslint": "true",
+    "node.js.detected.package.tslint": "true",
+    "node.js.selected.package.eslint": "(autodetect)",
+    "node.js.selected.package.tslint": "(autodetect)",
+    "nodejs_package_manager_path": "npm",
+    "project.structure.last.edited": "Project",
+    "project.structure.proportion": "0.0",
+    "project.structure.side.proportion": "0.0",
+    "settings.editor.selected.configurable": "preferences.lookFeel",
+    "vue.rearranger.settings.migration": "true"
   }
-}</component>
-  <component name="RunManager" selected="JUnit.ComplexTests.complement1Test">
+}]]></component>
+  <component name="RunManager" selected="JUnit.ab1 in ETI_Abgabe">
     <configuration name="ComplexTests.complement1Test" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
       <module name="ETI_Abgabe" />
       <extension name="coverage">
@@ -87,6 +88,23 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
+    <configuration name="ComplexTests.plus1Test" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
+      <module name="ETI_Abgabe" />
+      <extension name="coverage">
+        <pattern>
+          <option name="PATTERN" value="ab1.tests.*" />
+          <option name="ENABLED" value="true" />
+        </pattern>
+      </extension>
+      <option name="PACKAGE_NAME" value="ab1.tests" />
+      <option name="MAIN_CLASS_NAME" value="ab1.tests.ComplexTests" />
+      <option name="METHOD_NAME" value="plus1Test" />
+      <option name="TEST_OBJECT" value="method" />
+      <dir value="$PROJECT_DIR$/src/test/java/ab1" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
     <configuration name="ComplexTests.union1Test" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
       <module name="ETI_Abgabe" />
       <extension name="coverage">
@@ -138,11 +156,11 @@
     </configuration>
     <recent_temporary>
       <list>
-        <item itemvalue="JUnit.ComplexTests.complement1Test" />
         <item itemvalue="JUnit.ab1 in ETI_Abgabe" />
+        <item itemvalue="JUnit.ComplexTests.plus1Test" />
+        <item itemvalue="JUnit.ComplexTests.complement1Test" />
         <item itemvalue="JUnit.ComplexTests.union1Test" />
         <item itemvalue="JUnit.ab1.tests in ETI_Abgabe" />
-        <item itemvalue="JUnit.ab1.tests in ETI_Abgabe" />
       </list>
     </recent_temporary>
   </component>
@@ -164,7 +182,7 @@
       <workItem from="1704700821945" duration="5461000" />
       <workItem from="1704712375384" duration="4940000" />
       <workItem from="1704717343016" duration="2934000" />
-      <workItem from="1704750167689" duration="81000" />
+      <workItem from="1704750167689" duration="1793000" />
     </task>
     <task id="LOCAL-00001" summary="changed a bit">
       <option name="closed" value="true" />
@@ -198,7 +216,15 @@
       <option name="project" value="LOCAL" />
       <updated>1704749811525</updated>
     </task>
-    <option name="localTasksCounter" value="5" />
+    <task id="LOCAL-00005" summary="fucking hell">
+      <option name="closed" value="true" />
+      <created>1704750289780</created>
+      <option name="number" value="00005" />
+      <option name="presentableId" value="LOCAL-00005" />
+      <option name="project" value="LOCAL" />
+      <updated>1704750289780</updated>
+    </task>
+    <option name="localTasksCounter" value="6" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
diff --git a/src/main/java/ab1/impl/GRUPPE/NFAImpl.java b/src/main/java/ab1/impl/GRUPPE/NFAImpl.java
index 57908e3..e678c18 100644
--- a/src/main/java/ab1/impl/GRUPPE/NFAImpl.java
+++ b/src/main/java/ab1/impl/GRUPPE/NFAImpl.java
@@ -16,6 +16,8 @@ public class NFAImpl implements NFA {
 
     private Set<Character> alphabet;
 
+    private Set<Character> completeAlphabet;
+
     private boolean isFinalized;
 
     public NFAImpl(String startState) {
@@ -25,6 +27,10 @@ public class NFAImpl implements NFA {
         this.transitions = new HashSet<>();
         this.acceptingStates = new HashSet<>();
         this.alphabet = new HashSet<>();
+        this.completeAlphabet = new HashSet<>();
+        for (char ch = 'a'; ch <= 'z'; ch++) {
+            this.completeAlphabet.add(ch);
+        }
         this.isFinalized = false;
 
     }
@@ -211,28 +217,55 @@ public class NFAImpl implements NFA {
         return intersectionNFA;
     }
 
-    // #TODO
     @Override
     public NFA concatenation(NFA other) throws FinalizedStateException {
         if (!this.isFinalized || !other.isFinalized()) {
             throw new FinalizedStateException();
         }
+
         NFAImpl concatenationNFA = new NFAImpl(this.initialState);
 
+        // Add states from 'this'
         concatenationNFA.states.addAll(this.states);
-        concatenationNFA.states.addAll(other.getStates());
 
+        // Add states from 'other', with renaming if necessary
+        Map<String, String> renamedStates = new HashMap<>();
+        for (String state : other.getStates()) {
+            String newState = changeIfNecessary(state, concatenationNFA.states);
+            renamedStates.put(state, newState); // Old state name -> New state name
+            concatenationNFA.states.add(newState);
+        }
+
+        // Add transitions from 'this'
         concatenationNFA.transitions.addAll(this.transitions);
-        concatenationNFA.transitions.addAll(other.getTransitions());
 
-        for (String accceptingState : this.acceptingStates) {
-            Transition epsilon = new Transition(accceptingState, null, other.getInitialState());
+        // Add transitions from 'other', updating state names
+        for (Transition transition : other.getTransitions()) {
+            String newFromState = renamedStates.getOrDefault(transition.fromState(), transition.fromState());
+            String newToState = renamedStates.getOrDefault(transition.toState(), transition.toState());
+            Transition newTransition = new Transition(newFromState, transition.readSymbol(), newToState);
+            concatenationNFA.transitions.add(newTransition);
+        }
+
+        // Connect accepting states of 'this' to the initial state of 'other' with epsilon transitions
+        String newOtherInitialState = renamedStates.getOrDefault(other.getInitialState(), other.getInitialState());
+        for (String acceptingState : this.acceptingStates) {
+            Transition epsilon = new Transition(acceptingState, null, newOtherInitialState);
             concatenationNFA.transitions.add(epsilon);
         }
 
+        // Set accepting states of the concatenated NFA to be the accepting states of 'other'
+        concatenationNFA.acceptingStates.clear();
+        for (String acceptingState : other.getAcceptingStates()) {
+            concatenationNFA.acceptingStates.add(renamedStates.getOrDefault(acceptingState, acceptingState));
+        }
+
+        concatenationNFA.finalizeAutomaton();
+
         return concatenationNFA;
     }
 
+
     @Override
     public NFA kleeneStar() throws FinalizedStateException {
         if (!this.isFinalized) {
@@ -256,6 +289,7 @@ public class NFAImpl implements NFA {
             nfa.transitions.add(loopBackTransition);
         }
 
+        nfa.finalizeAutomaton();
 
         return nfa;
     }
@@ -293,6 +327,8 @@ public class NFAImpl implements NFA {
         }
         */
 
+        nfa.finalizeAutomaton();
+
         return nfa;
     }
 
@@ -388,6 +424,8 @@ public class NFAImpl implements NFA {
             currentStates = epsilonClosure(currentStates, this);
         }
 
+
+
         return isAcceptingState(currentStates, this);
     }