vault backup: 2026-04-08 10:35:59

00 Inbox/29593929 - Alphabets.md

@@ -1,18 +1,26 @@
 ---
 created: 2026-04-08 10:09
 course: "[[29593850 - Automationtheory]]"
-topic: "#alphabets"
+topic: alphabets, characters
 related:
 type: lecture
-status: 🔴
+status: 🟢
 tags:
   - university
 ---
-	## 📌 Summary
+## 📌 Summary
 
 > [!abstract]
-> 
+> Definition and examples of alphabets.
 
 ---
 
 ## 📝 Content
+
+Alphabets are formal, non-empty, finite, sets of characters (or _letters_ or _symbols_). They are denoted by $Sigma$.
+
+$Sigma = {a, b}$
+> Alphabet $Sigma$ contains the characters $a$ and $b$.
+
+$Sigma = {a, ..., z, A, ..., Z, 0, ..., 9}$
+> usual alphabet for writing text