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2024-04-02 21:15:34 -07:00
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commit c10ef06d85
5 changed files with 84 additions and 35 deletions

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@ -27,8 +27,8 @@ and five edges (labeled $0, ... , 4$).
\end{center}
\definition{}
A \textit{path} in a graph is a sequence of adjacent edges. \par
In a directed graph, adjacent edges are those that start and end at the same node. \par
A \textit{path} in a graph is a sequence of adjacent edges, \par
In a directed graph, edges $a$ and $b$ are adjacent if $a$ ends at the node which $b$ starts at. \par
\vspace{2mm}
For example, consider the graph above. \par
The edges $0$ and $1$ are not adjacent, because $0$ and $1$ both \textit{end} at $b$. \par
@ -88,6 +88,9 @@ if any of these conditions are violated, why do we know that an Eulerian cycle (
\definition{}
Now, consider the $n$-subword problem over $\{\texttt{0}, \texttt{1}\}$. \par
We'll call the optimal solution to this problem a \textit{De Bruijn\footnotemark{} word} of order $n$. \par
@ -113,7 +116,7 @@ Show that the following bounds always hold:
\remark{}
Now, we'd like to show that the length of a De Bruijn word is always $2^n + n - 1$... \par
Now, we'd like to show that the length of a De Bruijn word is always $2^n + n - 1$ \par
That is, that the optimal solution to the subword problem always has $2^n + n - 1$ letters. \par
We'll do this by construction: for a given $n$, we want to build a word with length $2^n + n - 1$
that solves the binary $n$-subword problem.
@ -189,6 +192,16 @@ $G_2$ and $G_3$ are shown below.
\vfill
\pagebreak
\problem{}
Draw $G_4$.
@ -310,6 +323,16 @@ Find De Bruijn words of orders $2$, $3$, and $4$.
\vfill
\pagebreak
Let's quickly show that the process described in \ref{dbeuler}
indeed produces a valid De Bruijn word.