diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index b2709eb..c305441 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -78,7 +78,7 @@
       }
     ],
     "direction": "horizontal",
-    "width": 322.50418853759766
+    "width": 349.50418853759766
   },
   "right": {
     "id": "8a65bc0c1d4d98f2",
diff --git a/00 Inbox/29593852 - Strings.md b/00 Inbox/29593852 - Strings.md
index 95171d6..2f39ef6 100644
--- a/00 Inbox/29593852 - Strings.md	
+++ b/00 Inbox/29593852 - Strings.md	
@@ -1,8 +1,8 @@
 ---
 created: 2026-04-08 08:52
-course:
-topic:
-related:
+course: "[[29593850 - Automationtheory]]"
+topic: "#languages #string #character #kleene #regularExpressions"
+related: "[[29593850 - Automationtheory]]"
 type: lecture
 status: 🔴
 tags:
@@ -11,7 +11,7 @@ tags:
 ## 📌 Summary
 
 > [!abstract]
-> 
+> Overview of lecture 1 on `Wednesday, 2026/Apr/08`
 
 ---
 
@@ -25,16 +25,45 @@ $Sigma = {a, b}$
 
 ### Strings
 A string is a set of letters. If there is an alphabet $Sigma = {a,b}$ then `abba` is a string made from that alphabet.
-The empty string is denoted by $epsilon$.
+The empty string is denoted by $epsilon$, this is the neutral element.
 ### Concatenation
-String can be concatenated, where one string is appended to another. This operation is 
+String can be concatenated, where one string is appended to another.
+$"apple" dot "pie" = "applepie"$
+
+$&x = "apple" \ &y = "pie" \ &x dot y = "applepie"$
+
+Order of operations / Brackets do _not matter_.
+Any string concatenated with the empty string $epsilon$ will result in itself.
+
+### Exponentiation
+
 
 ### Reversing / Mirroring
 For a string $x = a_1 a_2 ... a_(n-1) a_n$ of length $n$, it's _mirrored string_ is given by 
 $$ x^("Rev") = a_n a_(n-1)...a_2 a_1$$
 
 ### Kleene Star
-Denoted by $Sigma^*$. The Kleene Star (or _Kleene Closure_) 
+Denoted by $Sigma^*$. The Kleene Star (or _Kleene Closure_) gives an infinite amount of strings made up of the characters of the alphabet.
 
+$$
+Sigma^* {a, b} = {epsilon, a, b, "aa", "ab", "ba", "bb", "aaa", "aab", ...}
+$$
+> Example of the Kleene Star of the alphabet ${a, b}$
 ### Formal Languages
-A formal _language_ of the alphabet $Sigma$ is a subset $L$ of $Sigma^*$
\ No newline at end of file
+A formal _language_ of the alphabet $Sigma$ is a subset $L$ of $Sigma^*$
+
+### Finite representation of languages
+**Goal:** Represent a language using _finite_ information
+#### Using set notation
+$S = {a^n b^m bar n, m >= 0} = {epsilon, a, b, "aa", "ab", ...}$
+> This is very inefficient.
+
+#### Using regular expressions
+A _regular expression_ $r$ over an alphabet $Sigma$ is defined recursively:
+- $emptyset, epsilon$ and each $a in Sigma$ are regular expression, which represent the Languages $L(emptyset) = emptyset, L(epsilon) = {epsilon}$ and $L(a) = {a}$
+- If $r$ and $s$ are regular expressions then
+	- $(r+s)$
+<mark style="background: #FF5582A6;">	- !! Complete from leture notes</mark>
+
+### Regular languages
+A language $L$ that can be described by a regular expression $r$ (i. e. $L(r) = L$) is called _regular_.
\ No newline at end of file