diff --git a/Advanced/Knots/images/borromean.png b/Advanced/Knots/images/borromean.png new file mode 100644 index 0000000..853f0a9 Binary files /dev/null and b/Advanced/Knots/images/borromean.png differ diff --git a/Advanced/Knots/images/brunnian.png b/Advanced/Knots/images/brunnian.png new file mode 100644 index 0000000..f91fdcf Binary files /dev/null and b/Advanced/Knots/images/brunnian.png differ diff --git a/Advanced/Knots/images/whitehead a.png b/Advanced/Knots/images/whitehead a.png new file mode 100644 index 0000000..a3cc865 Binary files /dev/null and b/Advanced/Knots/images/whitehead a.png differ diff --git a/Advanced/Knots/images/whitehead b.png b/Advanced/Knots/images/whitehead b.png new file mode 100644 index 0000000..6e3e655 Binary files /dev/null and b/Advanced/Knots/images/whitehead b.png differ diff --git a/Advanced/Knots/main.tex b/Advanced/Knots/main.tex index d8c2730..bda14e5 100755 --- a/Advanced/Knots/main.tex +++ b/Advanced/Knots/main.tex @@ -37,8 +37,25 @@ \input{parts/0 intro.tex} \input{parts/1 composition.tex} + \input{parts/2 links.tex} + + + % Make sure the knot table is on an odd page + % so it may be removed in a double-sided + % handout. + \checkoddpage + \ifoddpage\else + \vspace*{\fill} + \begin{center} + { + \Large + \textbf{This page isn't empty.} + } + \end{center} + \vspace{\fill} + \pagebreak + \fi \input{parts/table} - \end{document} \ No newline at end of file diff --git a/Advanced/Knots/parts/0 intro.tex b/Advanced/Knots/parts/0 intro.tex index 611cd30..4812301 100644 --- a/Advanced/Knots/parts/0 intro.tex +++ b/Advanced/Knots/parts/0 intro.tex @@ -82,13 +82,9 @@ The simplest nontrivial knot is the \textit{trefoil} knot, shown to the right. \begin{center} \begin{minipage}[t]{0.48\textwidth} \begin{center} - \begin{tikzpicture}[baseline=(p), scale = 0.8] - \begin{knot} - \strand - (0,2) .. controls +(1.5,0) and +(1.5,0) .. - (0, 0) .. controls +(-1.5,0) and +(-1.5,0) .. - (0,2); - \end{knot} + \begin{tikzpicture}[baseline=(p)] + + \draw[circle] (0,0) circle (1); \coordinate (p) at (current bounding box.center); \end{tikzpicture} @@ -98,7 +94,6 @@ The simplest nontrivial knot is the \textit{trefoil} knot, shown to the right. \begin{minipage}[t]{0.48\textwidth} \begin{center} \begin{tikzpicture}[baseline=(p), scale = 0.8] - \clip (-2,-1.7) rectangle + (4, 4); \begin{knot}[ @@ -122,16 +117,16 @@ The simplest nontrivial knot is the \textit{trefoil} knot, shown to the right. \pagebreak \problem{} -Below are the only four distinct knots with only one crossing. \par -Show that no nontrivial knot can have has fewer than three crossings. \par -\hint{There are 4 such knots. What are they?} +Below are the only four knots with one crossing. \par +Show that every nontrivial knot more than two crossings. \par +\hint{There are four knots with two crossings. What are they?} \begin{center} \includegraphics[width=0.8\linewidth]{images/one crossing.png} \end{center} \begin{solution} - Draw all four. Each is isomorphic to the unknot. + Draw them all. Each is isomorphic to the unknot. \end{solution} \vfill @@ -147,7 +142,7 @@ A wire or an extension cord may help. \definition{} As we said before, there are many ways to draw the same knot. \par -We call each drawing a \textit{projection}. Below are four projections of the \textit{figure-eight} knot. +We call each drawing a \textit{projection}. Below are four projections of the \textit{figure-eight knot}. \vspace{2mm} @@ -157,7 +152,8 @@ We call each drawing a \textit{projection}. Below are four projections of the \t \vspace{2mm} \problem{} -Convince yourself that these are equivalent. +Convince yourself that these are equivalent. \par +Try to deform them into each other with a cord! \vfill \pagebreak \ No newline at end of file diff --git a/Advanced/Knots/parts/1 composition.tex b/Advanced/Knots/parts/1 composition.tex index 578889f..85cf2e7 100644 --- a/Advanced/Knots/parts/1 composition.tex +++ b/Advanced/Knots/parts/1 composition.tex @@ -53,8 +53,9 @@ Use a pencil or a cord to compose the figure-eight knot with itself. \pagebreak{} \problem{} -The following knots are composite. What are their prime components? \par -Try to make them with a cord! \par +The following knots are composite. \par +What are their prime components? \par +Try to make them with a cord. \par \hint{Use the table at the back of this handout to decompose the second knot.} \begin{center} diff --git a/Advanced/Knots/parts/2 links.tex b/Advanced/Knots/parts/2 links.tex new file mode 100644 index 0000000..5ab3745 --- /dev/null +++ b/Advanced/Knots/parts/2 links.tex @@ -0,0 +1,76 @@ +\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 \ No newline at end of file diff --git a/Advanced/Knots/parts/table.tex b/Advanced/Knots/parts/table.tex index c7dbb06..d3c24e9 100644 --- a/Advanced/Knots/parts/table.tex +++ b/Advanced/Knots/parts/table.tex @@ -1,15 +1,16 @@ \section{Table of Prime Knots} +A knot's \textit{crossing number} is the minimal number of crossings its projection must contain. In general, it is very difficult to determine a knot's crossing number. + +\vspace{1mm} + This table contains the 15 smallest prime knots, ordered by crossing number. \par -Mirror images are not accounted for, even if the mirror image produces a nonisomorphic knot. - -\vspace{5mm} - -% Images are from the appendix of the Knot book. +Mirror images are not included, even if the mirror image produces a nonisomorphic knot. \vfill +% Images are from the appendix of the Knot book. { - \def\w{25mm} + \def\w{24mm} \foreach \l/\c/\r in {% {3_1}/{4_1}/{5_1},% {5_2}/{6_1}/{6_2},% diff --git a/Advanced/Knots/tikzset.tex b/Advanced/Knots/tikzset.tex index 64fb30b..3b65f8f 100644 --- a/Advanced/Knots/tikzset.tex +++ b/Advanced/Knots/tikzset.tex @@ -17,6 +17,9 @@ \fi \tikzset{ + circle/.style = { + line width = 0.8mm, + }, knot diagram/every strand/.append style={ line width = 0.8mm, black