vault backup: 2026-04-08 13:00:12

This commit is contained in:
Jan Meyer
2026-04-08 13:00:12 +02:00
parent d21c72e4e7
commit 8bcf049ced
4 changed files with 135 additions and 92 deletions

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@@ -49,10 +49,6 @@ The $n^"th"$ power of the language $L subset.eq Sigma^*$ over alphabet $Sigma$
**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.
> This is limited in practice.
### 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
- $(r+s)$