diff --git a/opamp_circuits_C_GARRETT/Makefile b/opamp_circuits_C_GARRETT/Makefile
index dc495b2..506bb95 100644
--- a/opamp_circuits_C_GARRETT/Makefile
+++ b/opamp_circuits_C_GARRETT/Makefile
@@ -1,6 +1,6 @@
 
 
-PNG_DIA = circuit1_dag.png mvampcircuit.png pd.png invamp.png shared_component.png
+PNG_DIA = circuit1_dag.png mvampcircuit.png pd.png invamp.png shared_component.png tree_abstraction_levels.png
 
 
 
diff --git a/opamp_circuits_C_GARRETT/opamps.tex b/opamp_circuits_C_GARRETT/opamps.tex
index 50c9fcd..f0b889c 100644
--- a/opamp_circuits_C_GARRETT/opamps.tex
+++ b/opamp_circuits_C_GARRETT/opamps.tex
@@ -557,7 +557,16 @@ at even higher abstraction levels. Eventually we will have a hierarchy
 that converges to one top level {\dc}. At this stage we have a complete failure
 mode model of the system under investigation.
  
+\begin{figure}[h]
+ \centering
+ \includegraphics[width=200pt,keepaspectratio=true]{./tree_abstraction_levels.png}
+ % tree_abstraction_levels.png: 495x292 pixel, 72dpi, 17.46x10.30 cm, bb=0 0 495 292
+ \caption{FMMD Hierarchy showing ascending abstraction levels}
+ \label{fig:treeabslev}
+\end{figure}
 
+Figure~\ref{fig:treeabslev} shows an FMMD hierarchy, where the process of creating a {\dc} from a {\fg}
+is shown as a `$\bowtie$' symbol.
 
 
 \subsection{An algebraic notation for identifying FMMD enitities}
@@ -576,8 +585,8 @@ as
 \begin{equation}
 fm : \mathcal{C} \rightarrow \mathcal{P}\mathcal{F}.
 \end{equation}
-This is defined by, where C is a component and F is a set of failure modes,
-$  fm ( C ) = F. $
+This is defined by, where $c$ is a component and $F$ is a set of failure modes,
+$  fm ( c ) = F. $
 
 We can use the variable name $FG$ to represent a {\fg}. A {\fg} is a collection
 of components. 
@@ -603,12 +612,15 @@ fm : \mathcal{FG} \rightarrow \mathcal{P}\mathcal{F}.
 
 %$$ \mathcal{fm}(C) \rightarrow S $$
 %$$ {fm}(C) \rightarrow S $$
+\paragraph{Abstraction Levels of {\fgs} and {\dcs}}
+
+
 
 We can indicate the abstraction level of a component by using a superscript.
 Thus for the component $c$, where it is a `base component' we can assign it
 the abstraction level zero, $c^0$. Should we wish to index the components
-(for example as in a product parts~list) we can use a sub-script.
-Our base component (if first in the parts~list) could now be uniquely identified as
+(for example as in a product parts-list) we can use a sub-script.
+Our base component (if first in the parts-list) could now be uniquely identified as
 $c^0_1$.
 
 We can further define the abstraction level of a {\fg}.
diff --git a/opamp_circuits_C_GARRETT/three_tree.dia b/opamp_circuits_C_GARRETT/three_tree.dia
new file mode 100644
index 0000000..ce105bd
Binary files /dev/null and b/opamp_circuits_C_GARRETT/three_tree.dia differ
diff --git a/opamp_circuits_C_GARRETT/tree_abstraction_levels.dia b/opamp_circuits_C_GARRETT/tree_abstraction_levels.dia
new file mode 100644
index 0000000..8abbb57
Binary files /dev/null and b/opamp_circuits_C_GARRETT/tree_abstraction_levels.dia differ
diff --git a/presentations/fmea/fmea_pres.tex b/presentations/fmea/fmea_pres.tex
index d501b30..93d5f0e 100644
--- a/presentations/fmea/fmea_pres.tex
+++ b/presentations/fmea/fmea_pres.tex
@@ -1,4 +1,5 @@
-\documentclass{beamer}
+\documentclass[12pt]{beamer}
+%\documentclass[12pt,handout]{beamer}
 \title[Failure Mode Effects Analysis]{Failure Mode Effects Analysis\\A critical view}
 \usetheme{Warsaw}
 \usepackage[latin1]{inputenc}