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first figure for the intro
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UlrikBuchholtz committed Aug 10, 2023
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40 changes: 35 additions & 5 deletions intro.tex
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Expand Up @@ -49,12 +49,42 @@ \chapter{Introduction to the topic of this book}
\item
are these \emph{all} the symmetries?
\item ``rotation'' indicates a \emph{motion}, through different squares, joining $\square$ with itself via a ``journey in the world of squares''.
\begin{quote}
(picture of a little stick figure tipping a square over on its side along a path containing snapshots of the loop: I can draw one if you accept my analog artistic skills).
\end{quote}

How is that reconcilable with a precise notion of symmetry?
\end{enumerate}
\begin{center}
\begin{tikzpicture}
\foreach \x/\s in {45/0,35/1,25/2,15/3,5/4,-5/5,-15/6,-25/7,-35/8,-45/9} {
\begin{scope}[xshift=\s cm]
\draw (\x:.3) -- (\x+90:.3) -- (\x+180:.3) -- (\x+270:.3) -- cycle;
\end{scope}
}
% stick figure pushing
\begin{scope}[thick,line cap=round]
\node[dot] at (-.3,.3) {};
\draw (-.4,.1) -- (-.212,.1);
\draw (-.5,-.1) -- (-.35,.2);
\draw (-.5,-.1) -- (-.35,-.1);
\draw (-.5,-.1) -- (-.6,-.2);
\draw (-.35,-.1) -- (-.38,-.3);
\draw (-.38,-.3) -- (-.33,-.3);
\draw (-.6,-.2) -- (-.78,-.28);
\draw (-.78,-.28) -- (-.73,-.3);
\end{scope}
% stick figure resting
\begin{scope}[thick,line cap=round,xshift=9cm]
\node[dot] at (.5,.35) {};
\draw (.5,.25) -- (.5,-.05);
\draw (.5,-.05) -- (.6,-.3);
\draw (.6,-.3) -- (.65,-.3);
\draw (.5,-.05) -- (.4,-.3);
\draw (.4,-.3) -- (.35,-.3);
\draw (.5,.25) -- (.65,.1);
\draw (.65,.1) -- (.5,-.02);
\draw (.5,.25) -- (.35,.15);
\draw (.35,.15) -- (.212,.212);
\end{scope}
\end{tikzpicture}
\end{center}
How is that reconcilable with a precise notion of symmetry?

The answer to the first question clearly depends on the context. If we allow reflections or even more exotic symmetries the answer is ``no''. Each context has its own answer to what the symmetries of the square are.

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