vault backup: 2026-04-08 17:42:58

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Jan Meyer
2026-04-08 17:42:58 +02:00
parent 518f51dd42
commit 94aa5c9951
10 changed files with 27 additions and 20 deletions

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@@ -11,14 +11,15 @@ tags:
## 📌 Summary
> [!abstract]
>
> Definition and Examples of the Kleene Star, the Kleene Plus and the Lemma Group Structure
---
## 📝 Content
### Kleene Star
Denoted by $Sigma^*$. The Kleene Star (or _Kleene operator_ or _Kleene Closure_) gives an infinite amount of strings made up of the characters of the alphabet $Sigma ^ *$.
Denoted by $Sigma^*$. The Kleene Star (or _Kleene operator_ or _Kleene Closure_) gives an infinite amount of [[29593852 - Strings|strings]] made up of the characters of the [[29593929 - Alphabets|alphabets]] $Sigma ^ *$.
$Sigma^*$ is the set of all string that can be generated by arbitrary concatenation of its characters.
> $Sigma^* := union.big_(n>=0) A_n$
> where $A_n$ is the set of all string combinations of length $n$
@@ -38,7 +39,7 @@ $Sigma^*$ is the set of all string that can be generated by arbitrary concatenat
The _Kleene Plus_ of an alphabet $Sigma$ is given by $Sigma^+ = Sigma^* backslash {epsilon}$
### Lemma group structure
The structure _Lemma_ is induced by the Kleene star - it is a monoid, that is a semigroup with a neutral element.
The _Lemma group structure_ is induced by the [[29593935 - Kleene Star & Kleene Plus#Kleene Star|Kleene Star]] - it is a monoid, that is a semigroup with a neutral element.
> [!PROOF]
> - Associativity has been shown