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Operations Research
Notes Solution:
The activities C and D have a common predecessor A. The network representation shown in
Figure 12.12 (a), (b) violates the rule that no two activities can begin and end at the same events.
It appears as if activity B is a predecessor of activity C, which is not the case. To construct
the network in a logical order, it is necessary to introduce a dummy activity as shown in
Figure 12.13.
Figure 12.12: Network Representing the Error
E
C
A
B
D F
(a)
E
A C
B F
D
(b)
Figure 12.13: Correct Representation of Network
using Dummy Activity
C
E
A
Dummy
B F
D
Example: Construct a network for a project whose activities and their predecessor
relationship are given in Table 12.3.
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