File:MonadDistrMuPString.svg

\documentclass[10pt]{article}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
\begin{document}
\pagestyle{empty}
\tikzset{dot/.style={circle,fill=black,minimum size=1mm,inner sep=0mm}}
\begin{tikzpicture}[scale=0.4]
\path 
+(0,0)  coordinate[label=below:$\Sigma$] (O1)
+(4,0)  coordinate[label=below:$\Pi$]    (O2)
+(0,4)  coordinate[label=above:$\Pi$]    (I1)
+(2,4)  coordinate[label=above:$\Pi$]    (I2)
+(4,4)  coordinate[label=above:$\Sigma$] (I3)
+(3,3)  coordinate[dot, label=left:$\lambda$] (l1)
+(2,2)  coordinate[dot, label=left:$\lambda$] (l2)
+(3,1)  coordinate[dot, label=right:$\mu_\Pi$] (mu);
\draw (I1) -- (l2) -- (mu) -- (O2);
\draw (I2) -- (l1) to[out=-45, in=45] (mu);
\draw (I3) -- (l1) -- (l2) -- (O1);
\path 
+( 6,2)  coordinate[label=center:${=}$] (EQ)
+( 9,0)  coordinate[label=below:$\Sigma$] (O1)
+(11,0)  coordinate[label=below:$\Pi$]    (O2)
+( 8,4)  coordinate[label=above:$\Pi$]    (I1)
+(10,4)  coordinate[label=above:$\Pi$]    (I2)
+(12,4)  coordinate[label=above:$\Sigma$] (I3)
+( 9,2)  coordinate[dot, label=left:$\mu_\Pi$] (mu)
+(10,1)  coordinate[dot, label=left:$\lambda$] (l);
\draw (I1) to[out=-90,in=135] (mu) -- (l) -- (O2);
\draw (I2) to[out=-90,in=45] (mu);
\draw (I3) to[in=45, out=-90] (l) -- (O1);
\end{tikzpicture}
\end{document}