# HEA course for new maths lecturers

[2013-03-01 Fri]

If anyone finds it useful, I've created a LaTeX command for drawing
the octahedral axiom (requires the TikZ package) based on this example
of Stefan Kottwitz. You can easily edit the code to add labels to
arrows (they would go in the empty brackets in the lines that say “edge”) or add these as extra arguments to the function.

\usepackage{tikz}
\usetikzlibrary{arrows} \newcommand{\Octa}{\begin{center}
\begin{tikzpicture}[node distance=2cm,thick] \node (1) {$X$}; \node (4) [below right of=1] {$A$}; \node (6) [below right of=4] {$C$}; \node (2) [above right of=4] {$Y$}; \node (5) [above right of=6] {$B$}; \node (3) [above right of=5] {$Z$}; \draw[->] (1) to[out=25,in=155] (3); \draw[->] (1) -- (2); \draw[->] (2) -- (3); \draw[->] (2) -- (4); \draw[->] (3) -- (5); \draw[->] (3) to[out=260,in=0] (6); \draw[->] (4) -- (6); \draw[dashed,->] (4) -- (1); \draw[->] (6) -- (5); \draw[dashed,->] (4) -- (1); \draw[dashed,->] (5) -- (4); \draw[dashed,->] (5) -- (2); \draw[dashed,->] (6) to[out=180,in=270] (1);
\end{tikzpicture}
\end{center}}


Then the command

\Octa{X}{Y}{Z}{A}{B}{C}


will produce a diagram like this: 