---
created: 2026-04-08 10:09
course: "[[29593850 - Automationtheory]]"
topic: alphabets, characters
related:
type: lecture
status: 🟢
tags:
  - university
---
## 📌 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