diff --git a/fmmd_concept/System_safety_2011/presentation.odp b/fmmd_concept/System_safety_2011/presentation.odp
index 2dc30dc..427e485 100644
Binary files a/fmmd_concept/System_safety_2011/presentation.odp and b/fmmd_concept/System_safety_2011/presentation.odp differ
diff --git a/sw_model/sw_model.tex b/sw_model/sw_model.tex
index 8411d3b..a874876 100644
--- a/sw_model/sw_model.tex
+++ b/sw_model/sw_model.tex
@@ -215,6 +215,9 @@ the analysis stage; the symptoms, and finally the derived component.
 Now diagram showing software function,
 with pre-conditions, invariants and post conditions.
 
+define postcondition.
+define pre-condition:
+define invariant:
 
 Now an integrated diagram, showing the 
 pre-condition violations as failure modes