Added links to MUTEX in there

Very important to stress the results from
one stage of FMMD analysis create a {\dc}
with mut ex failure modes.

submission_thesis/CH2_FMEA/copy.tex

@@ -625,16 +625,28 @@ approach in looking for system failures.
 
 In this section we examine some fundamental concepts and underlying philosophies of FMEA.
 
+\paragraph{Failure modes of a component and mutual exclusivity.}
+It is desirable that the failure modes for a component are mutually exclusive, were a component able
+to fail in several ways at the same time, this would complicate analysis. 
+It would mean having to consider combinations of internal component failures
+as separate failure modes. This concept is discussed in sections ~\ref{ch4:mutex} 
+and ~\ref{ch7:mutex}.
+%
+In general failure modes
+for simple components   are mutually exclusive
+but large and complex components (such as integrated circuits), especially where they contain separate modules,
+could have non mutually exclusive failure modes and these need spacial handling, see section~\ref{ch3:mutex}.
 
 \paragraph{The signal path.}
 
 % C Garret does not like the terms afferent and efferent here, try to think of something else
 Most electronic systems are used to process a signal: with signal processing
-there is usually a clear afferent to transform to efferent path.
+there is usually a clear path from the signal coming into the system, it being processed in some way, and a resultant effect on
+an output or control signal. % afferent to transform to efferent path.
 %
 That is, there is an input, some processing and an output.
 %
-We define the signal path as the components used to process the signal.
+For the purpose of FMEA, we define the signal path as the components used to process the signal.
 %
 Some circuits have feedback loops or even circular signal paths, but it
 is normal for a signal path to exist.

submission_thesis/CH4_FMMD/copy.tex

@@ -2204,6 +2204,15 @@ in the model.
 With the above condition true, we term this a `complete' FMMD failure model.
 Ensuring this condition is described in section~\ref{sec:completetest}.
 
+\paragraph{Mutual exclusivity of {\dc} failure modes.}
+It is a desirable feature of a component that its failure modes
+are mutually exclusive.
+This also applies to {\dcs} produced in the FMMD process.
+In the FMMD process symptoms are are collected, i.e no component failure modes may be shared
+by a symptom within a {\fg}, and therefore the failure modes of a {\dc} are mutually exclusive.
+Thus FMMD naturally produces {\dc} failure modes that are mutually exclusive.
+This property is examined in more detail in section~\ref{ch7:mutex}.
+
 \paragraph{State explosion problem of FMEA solved by FMMD.}
 %
 Because FMMD considers failure modes within functional groups;