Added link section

Advanced/Knots/parts/2 links.tex

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+\section{Links}
+
+\definition{}
+A \textit{link} is a set of knots intertwined with each other. \par
+Just as with knots, we say that two links are \textit{isomorphic} if one can be deformed into the other.
+
+\vspace{2mm}
+
+The \textit{Whitehead link} is one of the simplest links we can produce. \par
+It consists of two knots, so we say it is a \textit{link of two components}.
+Two projections of the Whitehead link are shown below.
+
+
+\begin{center}
+	\hfill
+	\begin{minipage}[t]{0.27\textwidth}
+	\begin{center}
+		\includegraphics[width=\linewidth]{images/whitehead a.png}
+	\end{center}
+	\end{minipage}
+	\hfill
+	\begin{minipage}[t]{0.25\textwidth}
+	\begin{center}
+		\includegraphics[width=\linewidth]{images/whitehead b.png}
+	\end{center}
+	\end{minipage}
+	\hfill~
+\end{center}
+
+
+\definition{}
+The \textit{$n$-unlink} is the link that consists of $n$ disjoint unknots. \par
+The 3-unlink is shown below:
+
+\begin{center}
+	\begin{tikzpicture}
+
+	\draw[circle] (0,0) circle (0.7);
+	\draw[circle] (2,0) circle (0.7);
+	\draw[circle] (4,0) circle (0.7);
+
+	\end{tikzpicture}
+\end{center}
+
+\definition{}
+We say a nontrivial link is \textit{Brunnian} if we get an $n$-unlink after removing any component.
+
+\vspace{2mm}
+
+The \textit{Borromean Rings} are a common example of this. If we were to cut any of the three rings, the other two would fall apart.
+
+\begin{center}
+	\includegraphics[height=3cm]{images/borromean.png}
+\end{center}
+
+\vfill
+\pagebreak
+
+
+\problem{}
+Find a Brunnian link with four components.
+
+\vfill
+
+\problem{}
+Find a Brunnian link with $n$ components.
+
+\begin{solution}
+	\begin{center}
+		\includegraphics[width=40mm]{images/brunnian.png}
+	\end{center}
+\end{solution}
+
+
+\vfill
+\pagebreak