Diversity and Multi-Version Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 196

Table 5. Dependencies among diversity values

Dependencies

1 TC <----> MC TC1, TC2, TC3 <----> MC1, MC2, MC3

TC4, TC5, TC6 <----> MC4, MC5

2 MC <----> FC MC1, MC2 <----> FC1, FC2

MC3, MC4, MC5 <----> FC3, FC4, FC5, FC6

3 FC <----> TP FC1, FC2, FC4 <----> TP1, TP2

FC3, FC5, FC6 <----> TP3, TP4, TP5

4 TP <----> MP TP1, TP3, TP5 <----> MP1, MP2

TP2, TP4 <----> MP3, MP4

5 TC <----> L TC1, TC3 <----> L1, L2, L3

TC2, TC4, TC5, TC6 <----> L4, L5

6 L <----> TO L1 <----> TO1

L2, L3, L5 <----> TO2

L4 <----> TO3

7 TC <----> TO TC1, TC3, TC5, TC6 <----> TO1, TO2

TC2, TC4 <----> TO3

Figure 8. Model without dependencies

pendency 1 between TC and MC (Table 2), node
TC is split and new labels for input and output
edges are created (Figure 9), allowing only fea-
sible combinations of TC and MC values. The
formal rules for edge labeling can be found in
(Vilkomir, et al., 2009).
To reflect dependency 2 from Table 5, node
MC must be split. The result with new edge labels
is shown in Figure 10. Note that that there is no

connection between a lower TC and upper MC
nodes. The reason is that this edge was labeled
with the empty set at step 2 of the algorithm ap-
plication. This means that a corresponding com-
bination of diversity values is impossible. Such
edges are considered as “dead” and are elimi-
nated at step 3 of the algorithm application.
Figure 11 models dependency 3 between FC
and TP nodes. Similar to the diagram in Figure

Figure 9. Model of dependency 1