diff --git a/eulerg/eulerg.tex b/eulerg/eulerg.tex
index c7acdc7..d0c56d3 100644
--- a/eulerg/eulerg.tex
+++ b/eulerg/eulerg.tex
@@ -149,10 +149,12 @@ The diagram in figure \ref{fig:eulerg_enc} can now be represented as a graph thu
 
 \pagebreak[0]
 \section{The {\pic}}
-
+In graph theory a node is said to be reachable from another node
+if you can start at the one node, travel via the edges
+and arrive at the other. 
 Contours may be connected via `pure intersection' relationships to form 
 `chains' of contours reachable by pure intersection.
-
+These are termed {\pic}s.
 Figure \ref{fig:eulerg_pic} shows a {\pic} consisting of contours $M,N,O,P$ and $Q$.
 
 \begin{figure}[h]